Research ArticleSynthesis of Peripherally Tetrasubstituted Phthalocyanines andTheir Applications in Schottky Barrier Diodes

Semih Gorduk1 Ozge Koyun1 Oguzhan Avciata2 Ahmet Altindal3 and Ulvi Avciata14

1Faculty of Arts and Science Department of Chemistry Yildiz Technical University Esenler 34210 Istanbul Turkey2Faculty of Chemical and Metallurgical Engineering Department of Metallurgical and Materials Engineering Yildiz TechnicalUniversity Esenler 34210 Istanbul Turkey3Faculty of Arts and Science Department of Physics Yildiz Technical University Esenler 34210 Istanbul Turkey4Department of Occupational Health and Safety Esenyurt University Esenyurt 34510 Istanbul Turkey

Correspondence should be addressed to Semih Gorduk semih grdkhotmailcom and Ulvi Avciata uavciatagmailcom

Received 28 September 2017 Accepted 1 November 2017 Published 6 December 2017

Academic Editor Maria F Carvalho

Copyright copy 2017 Semih Gorduk et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

New metal-free and metallophthalocyanine compounds (Zn Co Ni and Cu) were synthesized using 2-hydroxymethyl-14-benzodioxan and 4-nitrophthalonitrile compounds All newly synthesized compounds were characterized by elemental analysisFT-IR UV-Vis 1H-NMR MALDI-TOF MS and GC-MS techniques The applications of synthesized compounds in Schottkybarrier diodes were investigated AgPcpndashSi structures were fabricated and charge transport mechanism in these devices wasinvestigated using dc technique It was observed from the analysis of the experimental results that the charge transport can bedescribed by Ohmic conduction at low values of the reverse bias On the other hand the voltage dependence of the measuredcurrent for high values of the applied reverse bias indicated that space charge limited conduction is the dominant mechanismresponsible for dc conduction From the observed voltage dependence of the current density under forward bias conditions it hasbeen concluded that the charge transport is dominated by Poole-Frenkel emission

1 Introduction

Phthalocyanines (Pcs) have drawn special interest due to theirparticular unique physicochemical properties and exhibita variety of superb properties such as architectural flex-ibility diverse coordination properties increased stabilityimproved spectroscopic characteristics and both semi- andphotoconductive characteristics [1 2]These properties makethem of considerable interest in diverse technological andscientific areas such as gas sensors [3] optoelectronic devices[4] static induction transistors [5] LangmuirndashBlodgett films[6] electrophotographic applications [7] optical data storage[8] solar cells [9] organic field-effect transistors (OFETs)[10] and nonlinear optics [11] In the fields of electronicsand optoelectronics Pcs are very promising candidates forfuture technology The application of Pc compounds forelectronics and optoelectronics devices is related to thedielectric relaxation process and electrical conductivity in the

Pc compounds and these are frequently the deciding factorsabout the compatibility of the material for a specific deviceapplication [12 13]

As main building blocks of various electronic and opto-electronic devices such as microwave diodes solar cells andphotodetectors [14 15] Schottky barrier diodes (SBDs) playa crucial role in the further development of the electronicdevices High barrier height and low leakage current arethe most important performance parameters for a SBDAlthough important advances have been made toward highperformance SBD a lot of improvement is still needed forpractical applications There are currently a vast number ofexperimental studies on the realization and the manipulationof the Schottky barrier height and the leakage currentusing an organic interlayer In this respect Pc compoundsoffer several advantages over inorganic counterparts suchas strontium titanate (SrTiO3) [16] and hafnium dioxide(HfO2) [17] because of their low cost suitability for synthetic

HindawiJournal of ChemistryVolume 2017 Article ID 9715069 9 pageshttpsdoiorg10115520179715069

2 Journal of Chemistry

modification and ease of device fabrication Therefore theunderstanding of the physical behavior of these compoundsunder dc condition is essential in order to decide suitabilityand improving the quality and performance of SBD basedelectronic devices

Herein our study presents the synthesis and charac-terization of new peripherally tetrasubstituted phthalocya-nines After their widespread use as active layer in manydifferent applications 2(3)9(10)16(17)23(24)-tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxy phthalocyaninesare proposed as an interlayer in SBDs The effects of thecentral metal ion in the Pc layer on the leakage current in p-Sibased SBDs have also been investigated

2 Experimental Section

21 Materials and Equipment 1198731198731015840-Dimethylformamide(DMF) dimethyl sulfoxide (DMSO) chloroform (CHCl3)diethyl ether methanol (MeOH) tetrahydrofuran (THF)ethanol (EtOH) dichloromethane (DCM) n-hexane n-pentanol and acetone were purchased from MERCK 4-Nitrophthalonitrile 2-hydroxymethyl-14-benzodioxan 18-diazabicyclo[540]undec-7-ene (DBU) potassium carbon-ate (K2CO3) zinc(II) acetate cobalt(II) acetate nickel(II)acetate copper(II) acetate were purchased from AldrichAll chemicals were of reagent grade All solvents weredried and stored over molecular sieves The progress ofthe reactions was monitored by thin layer chromatography(TLC) Melting points of the substances were determinedusing an Electrothermal Gallenkamp device The IR spectrawere recorded using a Perkin Elmer spectrophotometer withATR sampling accessory UV-Vis spectra were recorded on aAgilent 8453UVVis spectrophotometer Elemental analyseswere carried out by a LECO CHNS 932 instrument A VarianUnity Inova 500MHz spectrophotometer was used for 1HNMR and 13C NMR spectra Mass spectra of the synthesizedsubstances were acquired by using a Bruker Microflex LTMALDI-TOF MS GC-MS spectrum was obtained on anAgilent Technologies 6890N GC-System-5973 IMSD

22 Synthesis of Compounds

221 4-((23-Dihydrobenzo[b][14]dioxin-2-yl)methoxy)phthal-onitrile (1) 2-Hydroxymethyl-14-benzodioxan (052 g 289mmol) was dissolved in DMF (30ml) under nitrogen and4-nitrophthalonitrile (05 g 289mmol) was added Afterstirring for 20min at room temperature finely ground anhy-drous K2CO3 (196 g 1445mmol) was added to this mixturein portions over 2 h with efficient stirring The reactionmixture was stirred under a nitrogen atmosphere at 50∘Cfor a total of 24 h The reaction mixture was cooled to roomtemperature and was then poured into 200ml ice-water andthe precipitate that formedwas filtered offwashedwithwatern-hexane and diethyl ether and then dried The creamycrude product was recrystallized from MeOH Finally thepure powder was dried in a vacuum This compound wassoluble in MeOH EtOH acetone DCM and CHCI3 Yield076 g (90) Mp 145-146∘C Anal Calc for C17H12N2O3 C6986 H 414 N 958 Found C 6955 H 402 N 930

IR (ATR cmminus1) 3048 (Ar-CH) 2935ndash2889 (Aliphatic-CHCH2) 2228 (CequivN) 1604ndash1493 (C=C) 1275ndash1253 (C-O-C)1091 848 760 1H NMR (Acetone-d6) (120575 ppm) 788ndash786760ndash759 (d 2H Ar-H) 743ndash741 (dd 1H Ar-H) 675ndash671(m 4H Ar-H) 456ndash452 (s 1H CH) 442ndash409 (m 4HCH2)

13C NMR (CDCl3) (120575 ppm) 16135 14288 1423213537 12221 12202 11979 11946 11766 11748 11549 (CequivN)11508 (CequivN) 10825 7090 6730 6464 MS (GCndashMS)119898119911Calc 29208 Found 292 [M]+

222 General Synthesis Procedure for Phthalocyanine De-rivatives (2ndash6) The mixture of phthalonitrile compound(1) (02 g 069mmol) n-pentanol (4mL) 18-diazabicy-clo[450]undec-7-ene (DBU) (5 drops) no metal salt forcompound (2) and equivalent amounts of anhydrousZn(CH3COO)2 for compound (3) Co(CH3COO)2 forcompound (4) Ni(CH3COO)2 for compound (5) andCu(CH3COO)2 for compound (6) were heated to 160∘C andstirred for 24 h at this temperature under N2 atmosphereThen after cooling to room temperature the reactionmixturewas precipitated by the addition of n-hexane and filtered offAfter washing with hot MeOH and hot EtOH the productwas purified with column chromatography by using silicagel and THFCHCI3 solvent system The all phthalocyanines(2ndash6) were soluble in THF CHCI3 DMF and DMSO

(1) 2(3)9(10)16(17)23(24)-Tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxy Phthalocyanine (2) Solvent systemfor column chromatographywasTHF CHCI3 (100 3) Yield65mg (32) Mp gt200∘C Anal calc for C68H50N8O12C 6924 H 430 N 957 Found C 6901 H 405 N943 IR (ATR cmminus1) 3289 (single bond NH) 3046 (Ar-CH) 2929ndash2871 (Aliphatic-CH CH2) 1610ndash1491 (C=C)1264ndash1235 (C-O-C) 1095 837 742 1H-NMR (CDCI3) (120575ppm) 767ndash758 (bm 6H Ar-H) 740ndash715 (bm 6H Ar-H) 698ndash682 (bm 16H Ar-H) 495 (bs 4H Aliphatic-CH) 460ndash420 (bm 16H Aliphatic-CH2) UV-vis (THF 1 times10minus5M) 120582maxnm (log 120576) 701 (499) 664 (501) 639 (482)607 (468) 332 (507) MS (MALDI-TOF) (119898119911) Calc117117 Found 117131 [M]+

(2) 2(3)9(10)16(17)23(24)-Tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxy Phthalocyaninato Zinc(II) (3) Sol-vent system for column chromatography was THF CHCI3(100 3) Yield 96mg (45) Mp gt200∘C Anal calc forC68H48N8O12Zn C 6616 H 392 N 908 Found C 6597H 355 N 890 IR (ATR cmminus1) 3045 (Ar-CH) 2923ndash2876(Aliphatic-CH CH2) 1606ndash1489 (C=C) 1265ndash1232 (C-O-C) 1091 843 742 1H-NMR (CDCI3) (120575 ppm) 774ndash763(bm 6H Ar-H) 740ndash715 (bm 6H Ar-H) 698ndash644 (bm16H Ar-H) 494 (bs 4H Aliphatic-CH) 454ndash417 (bm 16HAliphatic-CH2) UV-vis (THF 1 times 10minus5M) 120582maxnm (log 120576)675 (500) 609 (431) 351 (468) MS (MALDI-TOF) (119898119911)Calc 123454 Found 123451 [M]+

(3) 2(3)9(10)16(17)23(24)-Tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxy Phthalocyaninato Cobalt(II) (4) Sol-vent system for column chromatography was THF CHCI3(100 2) Yield 85mg (40) Mp gt200∘C Anal calc for

Journal of Chemistry 3

C68H48CoN8O12 C 6650 H 394 N 912 Found C 6605H 355 N 885 IR (ATR cmminus1) 3064 (Ar-CH) 2954ndash2870(Aliphatic-CH CH2) 1609ndash1492 (C=C) 1265ndash1232 (C-O-C)1093 838 743 UV-vis (THF 1 times 10minus5M) 120582maxnm (log 120576)663 (501) 603 (454) 329 (508) MS (MALDI-TOF) (119898119911)Calc 122727 Found 122715 [M]+

(4) 2(3)9(10)16(17)23(24)-Tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxy Phthalocyaninato Nickel(II) (5) Sol-vent system for column chromatography was THF CHCI3(100 25) Yield 74mg (35) Mp gt200∘C Anal calc forC68H48N8NiO12 C 6652 H 394 N 913 Found C 6610H 358 N 885 IR (ATR cmminus1) 3044 (Ar-CH) 2927ndash2871(Aliphatic-CH CH2) 1608ndash1491 (C=C) 1264ndash1237 (C-O-C) 1092 840 742 1H-NMR (CDCI3) (120575 ppm) 774ndash766(bm 6H Ar-H) 739ndash719 (bm 6H Ar-H) 698ndash644 (bm16H Ar-H) 495 (bs 4H Aliphatic-CH) 457ndash421 (bm 16HAliphatic-CH2) UV-vis (THF 1 times 10minus5M) 120582maxnm (log 120576)662 (510) 612 (467) 327 (508) MS (MALDI-TOF) (119898119911)Calc 122785 Found 122779 [M]+

(5) 2(3)9(10)16(17)23(24)-Tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxy Phthalocyaninato Copper(II) (6) Sol-vent system for column chromatography was THF CHCI3(100 25) Yield 77mg (37) Mp gt200∘C Anal calc forC68H48CuN8O12 C 6626 H 392 N 909 Found C 6590H 356 N 887 IR (ATR cmminus1) 3044 (Ar-CH) 2929ndash2870(Aliphatic-CH CH2) 1606ndash1491 (C=C) 1264ndash1235 (C-O-C)1091 841 743 UV-vis (THF 1 times 10minus5M) 120582maxnm (log 120576) 675(501) 611 (457) 332 (482) MS (MALDI-TOF) (119898119911) Calc123270 Found 123234 [M]+

23 Fabrication and Characterization of SBDs The p-type Siwafers with (100) orientation and resistivity in the 8ndash10Ω cmrange were used as substrate After cleaning the Si wafersusing standard RCA cleaning procedure Al metal was ther-mally evaporated under 4 times 10minus5mbar pressure onto the Siwafers and followed by a heat treatment at 500∘C for 3min inN2 atmosphere in order to form the Ohmic contacts Afterthe removing of native oxide layer on the polished surfaceof the Si wafers by HFH2O (1 8) solution thin films of thePc compounds were formed onto the polished surface of Sisubstrate by spin coating techniqueThe thickness of the filmswas determined by ellipsometric technique After the spincoating of the interface layer 1mm in diameter and 2000 Athick Ag Schottky contacts were deposited on the the Pclayer by thermal evaporation technique In this way AgPcfilmp-Si Schottky barrier diodes were fabricated Current-voltage (119868-119881) characteristics of the devices were measuredunder vacuum (lt10minus3mbar) using an electrometer (KeithleyModel 617)

3 Results and Discussion

31 Synthesis and Characterization of Compounds The gen-eral synthetic pathway for the synthesis of 4-((23-dihy-drobenzo[b][14]dioxin-2-yl)methoxy)phthalonitrile (1) andits metal-free (2) zinc(II) (3) cobalt(II) (4) nickel(II) (5)and copper(II) (6) phthalocyanine complexes was given

in Scheme 1 Initial compound 1 was synthesized by thenucleophilic aromatic substitution reaction of compound 2-hydroxymethyl-14-benzodioxan with 4-nitrophthalonitrilein DMF at 50∘C for 24 h New phthalocyanines (2ndash6)were synthesized using corresponding anhydrous metal saltsandor without metal salt in 3mL n-pentanol for 24 h at160∘C under N2 atmosphere in the presence of DBU Struc-tures of synthesized compounds were verified by elementalanalysis UV-vis FT-IR 1H NMR 13C NMR and massspectroscopy techniques According to the IR spectrum of1 a new vibration that appeared at 2228 cmminus1 proved theformation of 1 The FT-IR spectrum of 1 showed aromaticbond -CH peaks at around 3013ndash3048 cmminus1 and aromatic-C=C peaks at around 1604ndash1592 cmminus1 The stretching peaksat 2935ndash2880 cmminus1 confirmed the presence of -CH and-CH2 groups

1H NMR spectrum of 1 (Figure S1) exhibitedaromatic protons integrating for a total of 7 protons at788ndash786 760ndash759 743ndash741 and 675ndash671 ppm In additionCH and CH2 protons of 1 were observed at 456ndash452 and442ndash409 ppm which integrated for 5 protons 13C NMR of1 (Figure S2) is another evidence for proposed structure thenewbands observed at 11549 and 11508 ppmcould be definedas carbons of nitrile groupsThemolecular ion peak for 1wasobserved at 292 119898119911 in its GC-MS spectrum which verifiedthe formation of this phthalonitrile

FT-IR spectra of the phthalocyanine compounds are verysimilar to each other The proposed target structures of allnew phthalocyanines were affirmed in the FT-IR spectra bythe disappearance of the -CequivN vibration at 2228 cmminus1 forphthalonitrile (1) For metal-free phthalocyanine (2) innercore -NH vibration was observed at 3289 cmminus1 and this peakwas the essential difference between the IR spectral data ofmetallophthalocyanines and metal-free ones In the FT-IRspectra of phthalocyanines (2ndash6) stretching vibrations ofaromatic CH groups around 3064ndash3044 cmminus1 aliphatic-CHCH2 groups around 2954ndash2870 cmminus1 and aromatic -C=Cgroups around 1610ndash1489 cmminus1 appeared at expected frequen-cies In the 1H NMR spectra of 2 3 and 5 phthalocyanines(Figures S3 S4 and S5) the bands belonging to the phthalo-cyanine and substitute 2-hydroxymethyl-14-benzodioxanaromatic protons were observed between 767 and 682 ppmfor compound 2 between 774 and 644 ppm for compound3 and between 774 and 644 ppm for compound 5 as broadmultiplet peaks In addition the aliphatic-CH protons for 23 and 5 were assigned at around 495 494 and 495 ppmrespectively as broad single peaksThe aliphatic CH2 protonsfor 2 3 and 5 were also assigned at around 460ndash420454ndash417 and 457ndash421 ppm respectively as broad multipletpeaks For 2 the typical shielding of inner core protons couldnot be observed due to the strong aggregation between Pcmolecules [18] The 1H NMR spectrum of compounds 4and 6 could not be determined because of the presence ofparamagnetic copper and cobalt ions [19] The MALDI-TOFmass spectra of the phthalocyanines (2ndash6) show the presenceof characteristic peaks at 119898119911 = 117131 [M]+ for 2 123451[M]+ for 3 122715 [M]+ for 4 122779 [M]+ for 5 and 123234[M]+ for 6 confirming the proposed structures (Figure 1)

4 Journal of Chemistry

O

O

OH +

N

NO

N

N

O

O

N

N

N

NN

N

N

N

OO

O

O

O O

O

OO

O

OO

M 2H (2) Zn (3) Co (4) Ni (5) Cu (6)

n-Pe

ntan

ol D

BU

(1)

2

DMF ＋23

2 24 h 50∘C

24

h160∘ C

M

Scheme 1 Schematic representation of synthesized compounds (1ndash6)

UV-Vis spectroscopy is thought to be the basic method toverify the formation of phthalocyaninesThe phthalocyaninecompounds show two main electronic transitions namedas Q band (600ndash700 nm in the visible region) assigned tothe 120587-120587lowast transition from the highest occupied molecular

orbital (HOMO) to the lowest unoccupied molecular orbital(LUMO) of the Pc ring and B band (300ndash350 nm in the UVregion) resulting from the deeper 120587-120587lowast transitions [20ndash22]The UV spectra of the metallophthalocyanines (3ndash6) displayintense Q band at 675 nm for 3 663 nm for 4 671 nm for 5

Journal of Chemistry 5

4400

200

300

100

0

Inte

ns (

au)

mz

1600

1400

1300

1500

1700

1200

1100

1000

122

715

4

900

800

5

800

1000

400

600

200

0In

tens

(au

)

mz

1600

1400

1300

1500

1700

1200

1100

100090

0

800

122

779

31

215

078

31000

1200

200

400

600

800

0

Inte

ns (

au)

mz

1500

1600

1700

1400

1300

1200

1100

100090

0

123

451

22600

200

0

Inte

ns (

au)

1500

1400

1300

1200

1100

100090

0

800

700

600

117

131

5mz

400

6

400

500

200

300

100

0

Inte

ns (

au)

mz

1800

1400

1300

1600

1700

1500

1200

1100

1000

123

234

6

900

800

Figure 1 The MALDI-TOF MS spectra of the phthalocyanines (2ndash6)

and 675 nm for 6 in THF The shoulders of phthalocyanines3ndash6 were observed at 609 603 617 and 611 nm respectivelyFor the Q band of phthalocyanines the longer wavelengthabsorptions are owing to the monomeric species and shorterwavelengths (shoulders) are due to the aggregated species[2] The B bands were observed at 351 nm for 3 329 nmfor 4 327 nm for 5 and 341 nm for 6 For the metal-freephthalocyanine (2) a split Q band was observed at 701 and664 nm while B band was observed at 332 nm (Figure 2)

32 Characterization of SBDs A device without Pc interfacelayer was also fabricated in order to verify the efficacy of theinsertion of Pc layer on the charge transfer characteristic ofthe devices For comparison the room temperature currentdensity (119869) voltage characteristics of the devices are presentedin Figure 3 As is clear from Figure 3 all the devicesexhibit rectification behavior with different rectification ratio

between 7 for Agp-Si and 310 for Ag2P-Si structure atplusmn5 This results prove the good rectification performancefor the Pc layer inserted devices Leakage current is animportant factor influencing the performance of an SBDIt was found that the value of the leakage current den-sity for the Pc layer inserted devices varies between 229times 10minus7 Acm2 and 656 times 10minus7 Acm2 while the observedleakage current density was 138 times 10minus4 Acm2 for Agp-Sistructure It should be mentioned here that the observedlevel of leakage current density is significantly low whencompared with the reported values with similar structuresuch as AuPDIp-Si [23] and AlDNAp-Si [24] Schottkydevices This findings clearly show that the main perfor-mance parameters of a SBD such as rectification ratioand leakage current can be improved by modifying p-typesilicon surface with 2(3)9(10)16(17)23(24)-tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxyphthalocyanines

6 Journal of Chemistry

Wavelength (nm)800700600500400

234

56

00

02

04

06

Abso

rban

ce 08

10

12

14

Figure 2 UV-Vis spectra of phthalocyanines (2ndash6)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-SiAgp-Si

10minus10

10minus8

10minus6

10minus4

10minus2

J(A

＝Ｇ

2)

420

V (V)

minus2minus4

Figure 3 Room temperature 119869-119881 characteristics of the devices

Various models such as Fowler-Nordheim tunnelingPoole-Frenkel emission andOhmic and space charge limited(SCL) current have widely been used to understand thenature of the charge transport through an organic thin film[25ndash27] To investigate the dc conduction mechanism infabricated devices the obtained 119869-119881 data were replottedon double logarithmic scale for forward and reverse biasconditions in Figure 4

It will be clear from the analysis of the data presented inFigures 4(a) and 4(b) that there are two regions with differentslopes in double logarithmic 119869-119881 plots for both forwardand reverse bias conditions which is consistent with earlierreports on MetalPhthalocyanineMetal (MIM) structures

[28 29] A relatively small slope in 119869-119881 curves at low voltageregions is clear for both directions Special attention must begiven to interpreting the presented data in Figure 4 becausedifferent conduction mechanism can give rise to this typeof 119869-119881 characteristics A close analysis of the slopes of thecurves shown in Figure 4 indicates that the slopes of thecurves vary between 092 and 116 for reverse bias conditionswhich is indicative of the Ohmic conduction in this voltageregion On the other hand it was observed that the slopesof the 119869-119881 curves for forward bias vary between 215 and268 which cannot be considered in the framework of Ohmicconduction Therefore in order to identify the conductionmechanism taking place in AgPcp-Si structures the 119869-119881curves of the fabricated devices were analyzed separately forforward and reverse bias directions As mentioned beforethe reverse bias 119869-119881 characteristic of the devices at lowervoltage range can be explained by the Ohmic behavior ofthe device However a power law dependence in the formof 119869120572119881119904 with 119904 gt 2 reveals the presence of space chargelimited conductivity (SCLC) controlled by exponentiallydistributed trapping levels This type of 119869-119881 characteristichas been observed in some other Pc films such as copperphthalocyanine thin film [30] It should be mentioned herethat the reverse bias voltage at which the exponent 119904 deviatesfrom unity is nearly the same for all Pc modified devices Inorder to investigate whether our experimental data can beexplained using Poole-Frenkel emission we have plotted inFigure 5 ln(119869119881) versus 11988112 curves for all samples

In the case of Poole-Frenkel emission the relationshipbetween the current density and the applied voltage can beexpressed as given in [15]

119869 = 119860119881119889 exp(119902120593PF minus 120573PFradic119881119889119886119896119879 ) (1)

where 119860 is a fitting parameter 119889 is the thickness of the film119902120593PF is the required energy for an electron to escape from the

Journal of Chemistry 7

1 1001

V (V)

10minus11

10minus10

10minus9

10minus8

10minus7

10minus6

10minus5

10minus4

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(a)

1 1001

V (V)

10minus9

10minus8

10minus7

10minus6

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(b)

Figure 4 119869-119881 plots for forward (a) and reverse bias (b) conditions

minus12

minus15

minus18

minus21

minus24

ln(JV

)(A

＝Ｇ

2V)

04 08 12 16 20 2400

V12

(V)12

Agp-Si (R2= 0996)

Agp-Si (R2= 0998)

Agp-Si (R2= 0997)

Agp-Si (R2= 0996)

Agp-Si (R2= 0996)

Figure 5 Poole-Frenkel plots for the device investigated under forward bias condition

trap 119886 is the slope parameter and 120573PFradic119881 is barrier loweringAccording to (1) the plot of ln(119869119881) versus radic119881 should belinear if the charge transport takes place through Poole-Frenkel emissionGood correlation coefficients (1198772) obtainedfrom ln(119869119881) versus radic119881 plots reveal that the mechanismresponsible for conduction in AgPcp-Si structures underforward bias conditions can be described by the Poole-Frenkel emission

4 Conclusion

In this work we have defined the synthesis and characteriza-tion of peripherally tetrasubstituted metal-free zinc cobalt

nickel and copper phthalocyanine derivatives These newfive compounds were characterized by various techniquesIn order to get more quantitative information about chargetransport mechanism and the usability of these compoundstomodify themain SBDparameters such as rectification ratioand the leakage current SBDs with the structure of AgPcp-Si were fabricated and characterized Our experimentalresults showed that charge transport in these compounds takeplace via different mechanism in reverse and forward biasconditions Results from this preliminary analysis indicatedthat the compounds can be considered among other candi-dates as a potential passivation layer for the new SBD diodeswith high rectification ratio and low leakage current

8 Journal of Chemistry

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

This study was supported by the Research Fund of YildizTechnical University (Project no 2016-01-02-DOP01)

Supplementary Materials

Figure S1 1H-NMR spectrum of compound 1 Figure S213C-NMR spectrum of compound 1 Figure S3 1H-NMRspectrum of compound 2 Figure S4 1H-NMR spectrum ofcompound 3 Figure S5 1H-NMR spectrum of compound 5(Supplementary Materials)

References

[1] N B McKeown Phthalocyanine Materials Synthesis Structureand Function Cambridge University Press Cambridge UK1998

[2] C C Leznoff A B P Lever P Stuzhin O Khelevina andB Berezin Phthalocyanines Properties and Applications VCHPublishers New York NY USA 1996

[3] M Bouvet P Gaudillat and J-M Suisse ldquoPhthalocyanine-based hybridmaterials for chemosensingrdquo Journal of Porphyrinsand Phthalocyanines vol 17 no 10 pp 913ndash919 2013

[4] C G Claessens U Hahn and T Torres ldquoPhthalocyaninesFrom outstanding electronic properties to emerging applica-tionsrdquoThe Chemical Record vol 8 no 2 pp 75ndash97 2008

[5] M Kraus S Richler A Opitz et al ldquoHigh-mobility copper-phthalocyanine field-effect transistors with tetratetracontanepassivation layer and organicmetal contactsrdquo Journal of AppliedPhysics vol 107 no 9 Article ID 094503 2010

[6] T Basova A Hassan M Durmus A G Gurek and V AhsenldquoLiquid crystalline metal phthalocyanines Structural organiza-tion on the substrate surfacerdquo Coordination Chemistry Reviewsvol 310 pp 131ndash153 2016

[7] D S Weiss and M Abkowitz ldquoAdvances in organic photocon-ductor technologyrdquo Chemical Reviews vol 110 no 1 pp 479ndash526 2010

[8] R Ao L Kummerl and D Haarer ldquoPresent limits of data stor-age using dye molecules in solid matricesrdquo Advanced Materialsvol 7 no 5 pp 495ndash499 1995

[9] M-E Ragoussi M Ince and T Torres ldquoRecent advances inphthalocyanine-based sensitizers for dye-sensitized solar cellsrdquoEuropean Journal of Organic Chemistry no 29 pp 6475ndash64892013

[10] Y Zhang X Cai Y Bian and J Jiang ldquoOrganic semiconduc-tors of phthalocyanine compounds for field effect transistors(FETs)rdquo in Functional Phthalocyanine Molecular Materials JJiang Ed vol 135 of Structure and Bonding pp 275ndash321Springer Berlin Germany 2010

[11] D Dini M J F Calvete and M Hanack ldquoNonlinear opticalmaterials for the smart filtering of optical radiationrdquo ChemicalReviews vol 116 no 22 pp 13043ndash13233 2016

[12] A Altindal S Abdurrahmanoglu M Bulut and OBekaroglu ldquoCharge transport mechanism in bis(double-deckerlutetium(III) phthalocyanine) (Lu2Pc4) thin filmrdquo SyntheticMetals vol 150 no 2 pp 181ndash187 2005

[13] T S Shafai and T D Anthopoulos ldquoJunction propertiesof nickel phthalocyanine thin film devices utilising indiuminjecting electrodesrdquoThin Solid Films vol 398-399 pp 361ndash3672001

[14] N N Halder P Biswas S Kundu and P Banerji ldquoAup-SiSchottky junction solar cell Effect of barrier height modifica-tion by InP quantum dotsrdquo Solar EnergyMaterials amp Solar Cellsvol 132 pp 230ndash236 2015

[15] E Rhoderick and R Williams MetalndashSemiconductor ContactsClarendon Oxford UK 2nd edition 1988

[16] S Yadav and S Ghosh ldquoAmorphous strontium titanate film asgate dielectric for higher performance and low voltage opera-tion of transparent and flexible organic field effect transistorrdquoACS Applied Materials amp Interfaces vol 8 no 16 pp 10436ndash10442 2016

[17] J Tardy M Erouel A L Deman et al ldquoOrganic thin filmtransistors with HfO2 high-k gate dielectric grown by anodicoxidation or deposited by sol-gelrdquo Microelectronics Reliabilityvol 47 no 2-3 pp 372ndash377 2007

[18] U Demirbas M Piskin B Barut R Bayrak M Durmusand H Kantekin ldquoMetal-free zinc(II) and lead(II) phthalo-cyanines functioning with 3-(2H-benzo[d][123]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups Synthesis and inves-tigation of photophysical and photochemical propertiesrdquo Syn-thetic Metals vol 220 pp 276ndash285 2016

[19] U Demirbas D Akyuz B Barut R Bayrak A Koca and HKantekin ldquoElectrochemical and spectroelectrochemical prop-erties of thiadiazole substitutedmetallo-phthalocyaninesrdquo Spec-trochimica Acta Part A Molecular and Biomolecular Spec-troscopy vol 153 pp 71ndash78 2016

[20] G Gumrukcu M U Ozgur A Altindal A R Ozkaya B Salihand O Bekaroglu ldquoSynthesis and electrochemical electricaland gas sensing properties of novel mononuclear metal-freeZn(II) Ni(II) Co(II) Cu(II) Lu(III) and double-decker Lu(III)phthalocyanines substituted with 2-(2H-123-benzotriazol- 2-yl)-4-(1133-tetramethylbutyl) phenoxyrdquo Synthetic Metals vol161 no 1-2 pp 112ndash123 2011

[21] O Koyun S Gorduk B Keskin A Cetinkaya A Koca andU Avciata ldquoMicrowave-assisted synthesis electrochemistryand spectroelectrochemistry of phthalocyanines bearing tetraterminal-alkynyl functionalities and click approachrdquo Polyhe-dron vol 113 pp 35ndash49 2016

[22] G K Karaoglan G Gumrukcu S Gorduk N Can and A GulldquoNovel homoleptic dimeric zinc(II) phthalocyanines as gatedielectric for OFET devicerdquo Synthetic Metals vol 230 pp 7ndash112017

[23] O F Yuksel N Tugluoglu H Safak and M Kus ldquoThemodification of Schottky barrier height of Aup-Si Schottkydevices by perylene-diimiderdquo Journal of Applied Physics vol 113no 4 Article ID 044507 2013

[24] H M J Al-Tarsquoii Y M Amin and V Periasamy ldquoCalculation ofthe electronic parameters of an AlDNAp-Si schottky barrierdiode influenced by alpha radiationrdquo Sensors vol 15 no 3 pp4810ndash4822 2015

[25] B Keskin A Altindal U Avciata and A Gul ldquoAC andDC Conduction processes in octakis[(4-tert-butylbenzylthio)-porphyrazinato]Cu(II) thin films with gold electrodesrdquo Bulletinof Materials Science vol 37 no 3 pp 461ndash468 2014

[26] B Keskin S Arda Ozturkcan and A Altindal ldquoUltrasound-assisted rapid one-pot synthesis characterization and electricalproperties of a 120573-aminoketone with a ferrocenyl moietyrdquoPolyhedron vol 69 pp 135ndash140 2014

Journal of Chemistry 3

C68H48CoN8O12 C 6650 H 394 N 912 Found C 6605H 355 N 885 IR (ATR cmminus1) 3064 (Ar-CH) 2954ndash2870(Aliphatic-CH CH2) 1609ndash1492 (C=C) 1265ndash1232 (C-O-C)1093 838 743 UV-vis (THF 1 times 10minus5M) 120582maxnm (log 120576)663 (501) 603 (454) 329 (508) MS (MALDI-TOF) (119898119911)Calc 122727 Found 122715 [M]+

(4) 2(3)9(10)16(17)23(24)-Tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxy Phthalocyaninato Nickel(II) (5) Sol-vent system for column chromatography was THF CHCI3(100 25) Yield 74mg (35) Mp gt200∘C Anal calc forC68H48N8NiO12 C 6652 H 394 N 913 Found C 6610H 358 N 885 IR (ATR cmminus1) 3044 (Ar-CH) 2927ndash2871(Aliphatic-CH CH2) 1608ndash1491 (C=C) 1264ndash1237 (C-O-C) 1092 840 742 1H-NMR (CDCI3) (120575 ppm) 774ndash766(bm 6H Ar-H) 739ndash719 (bm 6H Ar-H) 698ndash644 (bm16H Ar-H) 495 (bs 4H Aliphatic-CH) 457ndash421 (bm 16HAliphatic-CH2) UV-vis (THF 1 times 10minus5M) 120582maxnm (log 120576)662 (510) 612 (467) 327 (508) MS (MALDI-TOF) (119898119911)Calc 122785 Found 122779 [M]+

(5) 2(3)9(10)16(17)23(24)-Tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxy Phthalocyaninato Copper(II) (6) Sol-vent system for column chromatography was THF CHCI3(100 25) Yield 77mg (37) Mp gt200∘C Anal calc forC68H48CuN8O12 C 6626 H 392 N 909 Found C 6590H 356 N 887 IR (ATR cmminus1) 3044 (Ar-CH) 2929ndash2870(Aliphatic-CH CH2) 1606ndash1491 (C=C) 1264ndash1235 (C-O-C)1091 841 743 UV-vis (THF 1 times 10minus5M) 120582maxnm (log 120576) 675(501) 611 (457) 332 (482) MS (MALDI-TOF) (119898119911) Calc123270 Found 123234 [M]+

23 Fabrication and Characterization of SBDs The p-type Siwafers with (100) orientation and resistivity in the 8ndash10Ω cmrange were used as substrate After cleaning the Si wafersusing standard RCA cleaning procedure Al metal was ther-mally evaporated under 4 times 10minus5mbar pressure onto the Siwafers and followed by a heat treatment at 500∘C for 3min inN2 atmosphere in order to form the Ohmic contacts Afterthe removing of native oxide layer on the polished surfaceof the Si wafers by HFH2O (1 8) solution thin films of thePc compounds were formed onto the polished surface of Sisubstrate by spin coating techniqueThe thickness of the filmswas determined by ellipsometric technique After the spincoating of the interface layer 1mm in diameter and 2000 Athick Ag Schottky contacts were deposited on the the Pclayer by thermal evaporation technique In this way AgPcfilmp-Si Schottky barrier diodes were fabricated Current-voltage (119868-119881) characteristics of the devices were measuredunder vacuum (lt10minus3mbar) using an electrometer (KeithleyModel 617)

3 Results and Discussion

31 Synthesis and Characterization of Compounds The gen-eral synthetic pathway for the synthesis of 4-((23-dihy-drobenzo[b][14]dioxin-2-yl)methoxy)phthalonitrile (1) andits metal-free (2) zinc(II) (3) cobalt(II) (4) nickel(II) (5)and copper(II) (6) phthalocyanine complexes was given

in Scheme 1 Initial compound 1 was synthesized by thenucleophilic aromatic substitution reaction of compound 2-hydroxymethyl-14-benzodioxan with 4-nitrophthalonitrilein DMF at 50∘C for 24 h New phthalocyanines (2ndash6)were synthesized using corresponding anhydrous metal saltsandor without metal salt in 3mL n-pentanol for 24 h at160∘C under N2 atmosphere in the presence of DBU Struc-tures of synthesized compounds were verified by elementalanalysis UV-vis FT-IR 1H NMR 13C NMR and massspectroscopy techniques According to the IR spectrum of1 a new vibration that appeared at 2228 cmminus1 proved theformation of 1 The FT-IR spectrum of 1 showed aromaticbond -CH peaks at around 3013ndash3048 cmminus1 and aromatic-C=C peaks at around 1604ndash1592 cmminus1 The stretching peaksat 2935ndash2880 cmminus1 confirmed the presence of -CH and-CH2 groups

1H NMR spectrum of 1 (Figure S1) exhibitedaromatic protons integrating for a total of 7 protons at788ndash786 760ndash759 743ndash741 and 675ndash671 ppm In additionCH and CH2 protons of 1 were observed at 456ndash452 and442ndash409 ppm which integrated for 5 protons 13C NMR of1 (Figure S2) is another evidence for proposed structure thenewbands observed at 11549 and 11508 ppmcould be definedas carbons of nitrile groupsThemolecular ion peak for 1wasobserved at 292 119898119911 in its GC-MS spectrum which verifiedthe formation of this phthalonitrile

FT-IR spectra of the phthalocyanine compounds are verysimilar to each other The proposed target structures of allnew phthalocyanines were affirmed in the FT-IR spectra bythe disappearance of the -CequivN vibration at 2228 cmminus1 forphthalonitrile (1) For metal-free phthalocyanine (2) innercore -NH vibration was observed at 3289 cmminus1 and this peakwas the essential difference between the IR spectral data ofmetallophthalocyanines and metal-free ones In the FT-IRspectra of phthalocyanines (2ndash6) stretching vibrations ofaromatic CH groups around 3064ndash3044 cmminus1 aliphatic-CHCH2 groups around 2954ndash2870 cmminus1 and aromatic -C=Cgroups around 1610ndash1489 cmminus1 appeared at expected frequen-cies In the 1H NMR spectra of 2 3 and 5 phthalocyanines(Figures S3 S4 and S5) the bands belonging to the phthalo-cyanine and substitute 2-hydroxymethyl-14-benzodioxanaromatic protons were observed between 767 and 682 ppmfor compound 2 between 774 and 644 ppm for compound3 and between 774 and 644 ppm for compound 5 as broadmultiplet peaks In addition the aliphatic-CH protons for 23 and 5 were assigned at around 495 494 and 495 ppmrespectively as broad single peaksThe aliphatic CH2 protonsfor 2 3 and 5 were also assigned at around 460ndash420454ndash417 and 457ndash421 ppm respectively as broad multipletpeaks For 2 the typical shielding of inner core protons couldnot be observed due to the strong aggregation between Pcmolecules [18] The 1H NMR spectrum of compounds 4and 6 could not be determined because of the presence ofparamagnetic copper and cobalt ions [19] The MALDI-TOFmass spectra of the phthalocyanines (2ndash6) show the presenceof characteristic peaks at 119898119911 = 117131 [M]+ for 2 123451[M]+ for 3 122715 [M]+ for 4 122779 [M]+ for 5 and 123234[M]+ for 6 confirming the proposed structures (Figure 1)

4 Journal of Chemistry

O

O

OH +

N

NO

N

N

O

O

N

N

N

NN

N

N

N

OO

O

O

O O

O

OO

O

OO

M 2H (2) Zn (3) Co (4) Ni (5) Cu (6)

n-Pe

ntan

ol D

BU

(1)

2

DMF ＋23

2 24 h 50∘C

24

h160∘ C

M

Scheme 1 Schematic representation of synthesized compounds (1ndash6)

UV-Vis spectroscopy is thought to be the basic method toverify the formation of phthalocyaninesThe phthalocyaninecompounds show two main electronic transitions namedas Q band (600ndash700 nm in the visible region) assigned tothe 120587-120587lowast transition from the highest occupied molecular

orbital (HOMO) to the lowest unoccupied molecular orbital(LUMO) of the Pc ring and B band (300ndash350 nm in the UVregion) resulting from the deeper 120587-120587lowast transitions [20ndash22]The UV spectra of the metallophthalocyanines (3ndash6) displayintense Q band at 675 nm for 3 663 nm for 4 671 nm for 5

Journal of Chemistry 5

4400

200

300

100

0

Inte

ns (

au)

mz

1600

1400

1300

1500

1700

1200

1100

1000

122

715

4

900

800

5

800

1000

400

600

200

0In

tens

(au

)

mz

1600

1400

1300

1500

1700

1200

1100

100090

0

800

122

779

31

215

078

31000

1200

200

400

600

800

0

Inte

ns (

au)

mz

1500

1600

1700

1400

1300

1200

1100

100090

0

123

451

22600

200

0

Inte

ns (

au)

1500

1400

1300

1200

1100

100090

0

800

700

600

117

131

5mz

400

6

400

500

200

300

100

0

Inte

ns (

au)

mz

1800

1400

1300

1600

1700

1500

1200

1100

1000

123

234

6

900

800

Figure 1 The MALDI-TOF MS spectra of the phthalocyanines (2ndash6)

and 675 nm for 6 in THF The shoulders of phthalocyanines3ndash6 were observed at 609 603 617 and 611 nm respectivelyFor the Q band of phthalocyanines the longer wavelengthabsorptions are owing to the monomeric species and shorterwavelengths (shoulders) are due to the aggregated species[2] The B bands were observed at 351 nm for 3 329 nmfor 4 327 nm for 5 and 341 nm for 6 For the metal-freephthalocyanine (2) a split Q band was observed at 701 and664 nm while B band was observed at 332 nm (Figure 2)

32 Characterization of SBDs A device without Pc interfacelayer was also fabricated in order to verify the efficacy of theinsertion of Pc layer on the charge transfer characteristic ofthe devices For comparison the room temperature currentdensity (119869) voltage characteristics of the devices are presentedin Figure 3 As is clear from Figure 3 all the devicesexhibit rectification behavior with different rectification ratio

between 7 for Agp-Si and 310 for Ag2P-Si structure atplusmn5 This results prove the good rectification performancefor the Pc layer inserted devices Leakage current is animportant factor influencing the performance of an SBDIt was found that the value of the leakage current den-sity for the Pc layer inserted devices varies between 229times 10minus7 Acm2 and 656 times 10minus7 Acm2 while the observedleakage current density was 138 times 10minus4 Acm2 for Agp-Sistructure It should be mentioned here that the observedlevel of leakage current density is significantly low whencompared with the reported values with similar structuresuch as AuPDIp-Si [23] and AlDNAp-Si [24] Schottkydevices This findings clearly show that the main perfor-mance parameters of a SBD such as rectification ratioand leakage current can be improved by modifying p-typesilicon surface with 2(3)9(10)16(17)23(24)-tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxyphthalocyanines

6 Journal of Chemistry

Wavelength (nm)800700600500400

234

56

00

02

04

06

Abso

rban

ce 08

10

12

14

Figure 2 UV-Vis spectra of phthalocyanines (2ndash6)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-SiAgp-Si

10minus10

10minus8

10minus6

10minus4

10minus2

J(A

＝Ｇ

2)

420

V (V)

minus2minus4

Figure 3 Room temperature 119869-119881 characteristics of the devices

Various models such as Fowler-Nordheim tunnelingPoole-Frenkel emission andOhmic and space charge limited(SCL) current have widely been used to understand thenature of the charge transport through an organic thin film[25ndash27] To investigate the dc conduction mechanism infabricated devices the obtained 119869-119881 data were replottedon double logarithmic scale for forward and reverse biasconditions in Figure 4

It will be clear from the analysis of the data presented inFigures 4(a) and 4(b) that there are two regions with differentslopes in double logarithmic 119869-119881 plots for both forwardand reverse bias conditions which is consistent with earlierreports on MetalPhthalocyanineMetal (MIM) structures

[28 29] A relatively small slope in 119869-119881 curves at low voltageregions is clear for both directions Special attention must begiven to interpreting the presented data in Figure 4 becausedifferent conduction mechanism can give rise to this typeof 119869-119881 characteristics A close analysis of the slopes of thecurves shown in Figure 4 indicates that the slopes of thecurves vary between 092 and 116 for reverse bias conditionswhich is indicative of the Ohmic conduction in this voltageregion On the other hand it was observed that the slopesof the 119869-119881 curves for forward bias vary between 215 and268 which cannot be considered in the framework of Ohmicconduction Therefore in order to identify the conductionmechanism taking place in AgPcp-Si structures the 119869-119881curves of the fabricated devices were analyzed separately forforward and reverse bias directions As mentioned beforethe reverse bias 119869-119881 characteristic of the devices at lowervoltage range can be explained by the Ohmic behavior ofthe device However a power law dependence in the formof 119869120572119881119904 with 119904 gt 2 reveals the presence of space chargelimited conductivity (SCLC) controlled by exponentiallydistributed trapping levels This type of 119869-119881 characteristichas been observed in some other Pc films such as copperphthalocyanine thin film [30] It should be mentioned herethat the reverse bias voltage at which the exponent 119904 deviatesfrom unity is nearly the same for all Pc modified devices Inorder to investigate whether our experimental data can beexplained using Poole-Frenkel emission we have plotted inFigure 5 ln(119869119881) versus 11988112 curves for all samples

In the case of Poole-Frenkel emission the relationshipbetween the current density and the applied voltage can beexpressed as given in [15]

119869 = 119860119881119889 exp(119902120593PF minus 120573PFradic119881119889119886119896119879 ) (1)

where 119860 is a fitting parameter 119889 is the thickness of the film119902120593PF is the required energy for an electron to escape from the

Journal of Chemistry 7

1 1001

V (V)

10minus11

10minus10

10minus9

10minus8

10minus7

10minus6

10minus5

10minus4

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(a)

1 1001

V (V)

10minus9

10minus8

10minus7

10minus6

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(b)

Figure 4 119869-119881 plots for forward (a) and reverse bias (b) conditions

minus12

minus15

minus18

minus21

minus24

ln(JV

)(A

＝Ｇ

2V)

04 08 12 16 20 2400

V12

(V)12

Agp-Si (R2= 0996)

Agp-Si (R2= 0998)

Agp-Si (R2= 0997)

Agp-Si (R2= 0996)

Agp-Si (R2= 0996)

Figure 5 Poole-Frenkel plots for the device investigated under forward bias condition

trap 119886 is the slope parameter and 120573PFradic119881 is barrier loweringAccording to (1) the plot of ln(119869119881) versus radic119881 should belinear if the charge transport takes place through Poole-Frenkel emissionGood correlation coefficients (1198772) obtainedfrom ln(119869119881) versus radic119881 plots reveal that the mechanismresponsible for conduction in AgPcp-Si structures underforward bias conditions can be described by the Poole-Frenkel emission

4 Conclusion

In this work we have defined the synthesis and characteriza-tion of peripherally tetrasubstituted metal-free zinc cobalt

nickel and copper phthalocyanine derivatives These newfive compounds were characterized by various techniquesIn order to get more quantitative information about chargetransport mechanism and the usability of these compoundstomodify themain SBDparameters such as rectification ratioand the leakage current SBDs with the structure of AgPcp-Si were fabricated and characterized Our experimentalresults showed that charge transport in these compounds takeplace via different mechanism in reverse and forward biasconditions Results from this preliminary analysis indicatedthat the compounds can be considered among other candi-dates as a potential passivation layer for the new SBD diodeswith high rectification ratio and low leakage current

8 Journal of Chemistry

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

This study was supported by the Research Fund of YildizTechnical University (Project no 2016-01-02-DOP01)

Supplementary Materials

Figure S1 1H-NMR spectrum of compound 1 Figure S213C-NMR spectrum of compound 1 Figure S3 1H-NMRspectrum of compound 2 Figure S4 1H-NMR spectrum ofcompound 3 Figure S5 1H-NMR spectrum of compound 5(Supplementary Materials)

References

[1] N B McKeown Phthalocyanine Materials Synthesis Structureand Function Cambridge University Press Cambridge UK1998

[2] C C Leznoff A B P Lever P Stuzhin O Khelevina andB Berezin Phthalocyanines Properties and Applications VCHPublishers New York NY USA 1996

[3] M Bouvet P Gaudillat and J-M Suisse ldquoPhthalocyanine-based hybridmaterials for chemosensingrdquo Journal of Porphyrinsand Phthalocyanines vol 17 no 10 pp 913ndash919 2013

[4] C G Claessens U Hahn and T Torres ldquoPhthalocyaninesFrom outstanding electronic properties to emerging applica-tionsrdquoThe Chemical Record vol 8 no 2 pp 75ndash97 2008

[5] M Kraus S Richler A Opitz et al ldquoHigh-mobility copper-phthalocyanine field-effect transistors with tetratetracontanepassivation layer and organicmetal contactsrdquo Journal of AppliedPhysics vol 107 no 9 Article ID 094503 2010

[6] T Basova A Hassan M Durmus A G Gurek and V AhsenldquoLiquid crystalline metal phthalocyanines Structural organiza-tion on the substrate surfacerdquo Coordination Chemistry Reviewsvol 310 pp 131ndash153 2016

[7] D S Weiss and M Abkowitz ldquoAdvances in organic photocon-ductor technologyrdquo Chemical Reviews vol 110 no 1 pp 479ndash526 2010

[8] R Ao L Kummerl and D Haarer ldquoPresent limits of data stor-age using dye molecules in solid matricesrdquo Advanced Materialsvol 7 no 5 pp 495ndash499 1995

[9] M-E Ragoussi M Ince and T Torres ldquoRecent advances inphthalocyanine-based sensitizers for dye-sensitized solar cellsrdquoEuropean Journal of Organic Chemistry no 29 pp 6475ndash64892013

[10] Y Zhang X Cai Y Bian and J Jiang ldquoOrganic semiconduc-tors of phthalocyanine compounds for field effect transistors(FETs)rdquo in Functional Phthalocyanine Molecular Materials JJiang Ed vol 135 of Structure and Bonding pp 275ndash321Springer Berlin Germany 2010

[11] D Dini M J F Calvete and M Hanack ldquoNonlinear opticalmaterials for the smart filtering of optical radiationrdquo ChemicalReviews vol 116 no 22 pp 13043ndash13233 2016

[12] A Altindal S Abdurrahmanoglu M Bulut and OBekaroglu ldquoCharge transport mechanism in bis(double-deckerlutetium(III) phthalocyanine) (Lu2Pc4) thin filmrdquo SyntheticMetals vol 150 no 2 pp 181ndash187 2005

[13] T S Shafai and T D Anthopoulos ldquoJunction propertiesof nickel phthalocyanine thin film devices utilising indiuminjecting electrodesrdquoThin Solid Films vol 398-399 pp 361ndash3672001

[14] N N Halder P Biswas S Kundu and P Banerji ldquoAup-SiSchottky junction solar cell Effect of barrier height modifica-tion by InP quantum dotsrdquo Solar EnergyMaterials amp Solar Cellsvol 132 pp 230ndash236 2015

[15] E Rhoderick and R Williams MetalndashSemiconductor ContactsClarendon Oxford UK 2nd edition 1988

[16] S Yadav and S Ghosh ldquoAmorphous strontium titanate film asgate dielectric for higher performance and low voltage opera-tion of transparent and flexible organic field effect transistorrdquoACS Applied Materials amp Interfaces vol 8 no 16 pp 10436ndash10442 2016

[17] J Tardy M Erouel A L Deman et al ldquoOrganic thin filmtransistors with HfO2 high-k gate dielectric grown by anodicoxidation or deposited by sol-gelrdquo Microelectronics Reliabilityvol 47 no 2-3 pp 372ndash377 2007

[18] U Demirbas M Piskin B Barut R Bayrak M Durmusand H Kantekin ldquoMetal-free zinc(II) and lead(II) phthalo-cyanines functioning with 3-(2H-benzo[d][123]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups Synthesis and inves-tigation of photophysical and photochemical propertiesrdquo Syn-thetic Metals vol 220 pp 276ndash285 2016

[19] U Demirbas D Akyuz B Barut R Bayrak A Koca and HKantekin ldquoElectrochemical and spectroelectrochemical prop-erties of thiadiazole substitutedmetallo-phthalocyaninesrdquo Spec-trochimica Acta Part A Molecular and Biomolecular Spec-troscopy vol 153 pp 71ndash78 2016

[20] G Gumrukcu M U Ozgur A Altindal A R Ozkaya B Salihand O Bekaroglu ldquoSynthesis and electrochemical electricaland gas sensing properties of novel mononuclear metal-freeZn(II) Ni(II) Co(II) Cu(II) Lu(III) and double-decker Lu(III)phthalocyanines substituted with 2-(2H-123-benzotriazol- 2-yl)-4-(1133-tetramethylbutyl) phenoxyrdquo Synthetic Metals vol161 no 1-2 pp 112ndash123 2011

[21] O Koyun S Gorduk B Keskin A Cetinkaya A Koca andU Avciata ldquoMicrowave-assisted synthesis electrochemistryand spectroelectrochemistry of phthalocyanines bearing tetraterminal-alkynyl functionalities and click approachrdquo Polyhe-dron vol 113 pp 35ndash49 2016

[22] G K Karaoglan G Gumrukcu S Gorduk N Can and A GulldquoNovel homoleptic dimeric zinc(II) phthalocyanines as gatedielectric for OFET devicerdquo Synthetic Metals vol 230 pp 7ndash112017

[23] O F Yuksel N Tugluoglu H Safak and M Kus ldquoThemodification of Schottky barrier height of Aup-Si Schottkydevices by perylene-diimiderdquo Journal of Applied Physics vol 113no 4 Article ID 044507 2013

[24] H M J Al-Tarsquoii Y M Amin and V Periasamy ldquoCalculation ofthe electronic parameters of an AlDNAp-Si schottky barrierdiode influenced by alpha radiationrdquo Sensors vol 15 no 3 pp4810ndash4822 2015

[25] B Keskin A Altindal U Avciata and A Gul ldquoAC andDC Conduction processes in octakis[(4-tert-butylbenzylthio)-porphyrazinato]Cu(II) thin films with gold electrodesrdquo Bulletinof Materials Science vol 37 no 3 pp 461ndash468 2014

[26] B Keskin S Arda Ozturkcan and A Altindal ldquoUltrasound-assisted rapid one-pot synthesis characterization and electricalproperties of a 120573-aminoketone with a ferrocenyl moietyrdquoPolyhedron vol 69 pp 135ndash140 2014

4 Journal of Chemistry

O

O

OH +

N

NO

N

N

O

O

N

N

N

NN

N

N

N

OO

O

O

O O

O

OO

O

OO

M 2H (2) Zn (3) Co (4) Ni (5) Cu (6)

n-Pe

ntan

ol D

BU

(1)

2

DMF ＋23

2 24 h 50∘C

24

h160∘ C

M

Scheme 1 Schematic representation of synthesized compounds (1ndash6)

UV-Vis spectroscopy is thought to be the basic method toverify the formation of phthalocyaninesThe phthalocyaninecompounds show two main electronic transitions namedas Q band (600ndash700 nm in the visible region) assigned tothe 120587-120587lowast transition from the highest occupied molecular

orbital (HOMO) to the lowest unoccupied molecular orbital(LUMO) of the Pc ring and B band (300ndash350 nm in the UVregion) resulting from the deeper 120587-120587lowast transitions [20ndash22]The UV spectra of the metallophthalocyanines (3ndash6) displayintense Q band at 675 nm for 3 663 nm for 4 671 nm for 5

Journal of Chemistry 5

4400

200

300

100

0

Inte

ns (

au)

mz

1600

1400

1300

1500

1700

1200

1100

1000

122

715

4

900

800

5

800

1000

400

600

200

0In

tens

(au

)

mz

1600

1400

1300

1500

1700

1200

1100

100090

0

800

122

779

31

215

078

31000

1200

200

400

600

800

0

Inte

ns (

au)

mz

1500

1600

1700

1400

1300

1200

1100

100090

0

123

451

22600

200

0

Inte

ns (

au)

1500

1400

1300

1200

1100

100090

0

800

700

600

117

131

5mz

400

6

400

500

200

300

100

0

Inte

ns (

au)

mz

1800

1400

1300

1600

1700

1500

1200

1100

1000

123

234

6

900

800

Figure 1 The MALDI-TOF MS spectra of the phthalocyanines (2ndash6)

and 675 nm for 6 in THF The shoulders of phthalocyanines3ndash6 were observed at 609 603 617 and 611 nm respectivelyFor the Q band of phthalocyanines the longer wavelengthabsorptions are owing to the monomeric species and shorterwavelengths (shoulders) are due to the aggregated species[2] The B bands were observed at 351 nm for 3 329 nmfor 4 327 nm for 5 and 341 nm for 6 For the metal-freephthalocyanine (2) a split Q band was observed at 701 and664 nm while B band was observed at 332 nm (Figure 2)

32 Characterization of SBDs A device without Pc interfacelayer was also fabricated in order to verify the efficacy of theinsertion of Pc layer on the charge transfer characteristic ofthe devices For comparison the room temperature currentdensity (119869) voltage characteristics of the devices are presentedin Figure 3 As is clear from Figure 3 all the devicesexhibit rectification behavior with different rectification ratio

between 7 for Agp-Si and 310 for Ag2P-Si structure atplusmn5 This results prove the good rectification performancefor the Pc layer inserted devices Leakage current is animportant factor influencing the performance of an SBDIt was found that the value of the leakage current den-sity for the Pc layer inserted devices varies between 229times 10minus7 Acm2 and 656 times 10minus7 Acm2 while the observedleakage current density was 138 times 10minus4 Acm2 for Agp-Sistructure It should be mentioned here that the observedlevel of leakage current density is significantly low whencompared with the reported values with similar structuresuch as AuPDIp-Si [23] and AlDNAp-Si [24] Schottkydevices This findings clearly show that the main perfor-mance parameters of a SBD such as rectification ratioand leakage current can be improved by modifying p-typesilicon surface with 2(3)9(10)16(17)23(24)-tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxyphthalocyanines

6 Journal of Chemistry

Wavelength (nm)800700600500400

234

56

00

02

04

06

Abso

rban

ce 08

10

12

14

Figure 2 UV-Vis spectra of phthalocyanines (2ndash6)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-SiAgp-Si

10minus10

10minus8

10minus6

10minus4

10minus2

J(A

＝Ｇ

2)

420

V (V)

minus2minus4

Figure 3 Room temperature 119869-119881 characteristics of the devices

Various models such as Fowler-Nordheim tunnelingPoole-Frenkel emission andOhmic and space charge limited(SCL) current have widely been used to understand thenature of the charge transport through an organic thin film[25ndash27] To investigate the dc conduction mechanism infabricated devices the obtained 119869-119881 data were replottedon double logarithmic scale for forward and reverse biasconditions in Figure 4

It will be clear from the analysis of the data presented inFigures 4(a) and 4(b) that there are two regions with differentslopes in double logarithmic 119869-119881 plots for both forwardand reverse bias conditions which is consistent with earlierreports on MetalPhthalocyanineMetal (MIM) structures

[28 29] A relatively small slope in 119869-119881 curves at low voltageregions is clear for both directions Special attention must begiven to interpreting the presented data in Figure 4 becausedifferent conduction mechanism can give rise to this typeof 119869-119881 characteristics A close analysis of the slopes of thecurves shown in Figure 4 indicates that the slopes of thecurves vary between 092 and 116 for reverse bias conditionswhich is indicative of the Ohmic conduction in this voltageregion On the other hand it was observed that the slopesof the 119869-119881 curves for forward bias vary between 215 and268 which cannot be considered in the framework of Ohmicconduction Therefore in order to identify the conductionmechanism taking place in AgPcp-Si structures the 119869-119881curves of the fabricated devices were analyzed separately forforward and reverse bias directions As mentioned beforethe reverse bias 119869-119881 characteristic of the devices at lowervoltage range can be explained by the Ohmic behavior ofthe device However a power law dependence in the formof 119869120572119881119904 with 119904 gt 2 reveals the presence of space chargelimited conductivity (SCLC) controlled by exponentiallydistributed trapping levels This type of 119869-119881 characteristichas been observed in some other Pc films such as copperphthalocyanine thin film [30] It should be mentioned herethat the reverse bias voltage at which the exponent 119904 deviatesfrom unity is nearly the same for all Pc modified devices Inorder to investigate whether our experimental data can beexplained using Poole-Frenkel emission we have plotted inFigure 5 ln(119869119881) versus 11988112 curves for all samples

In the case of Poole-Frenkel emission the relationshipbetween the current density and the applied voltage can beexpressed as given in [15]

119869 = 119860119881119889 exp(119902120593PF minus 120573PFradic119881119889119886119896119879 ) (1)

where 119860 is a fitting parameter 119889 is the thickness of the film119902120593PF is the required energy for an electron to escape from the

Journal of Chemistry 7

1 1001

V (V)

10minus11

10minus10

10minus9

10minus8

10minus7

10minus6

10minus5

10minus4

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(a)

1 1001

V (V)

10minus9

10minus8

10minus7

10minus6

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(b)

Figure 4 119869-119881 plots for forward (a) and reverse bias (b) conditions

minus12

minus15

minus18

minus21

minus24

ln(JV

)(A

＝Ｇ

2V)

04 08 12 16 20 2400

V12

(V)12

Agp-Si (R2= 0996)

Agp-Si (R2= 0998)

Agp-Si (R2= 0997)

Agp-Si (R2= 0996)

Agp-Si (R2= 0996)

Figure 5 Poole-Frenkel plots for the device investigated under forward bias condition

trap 119886 is the slope parameter and 120573PFradic119881 is barrier loweringAccording to (1) the plot of ln(119869119881) versus radic119881 should belinear if the charge transport takes place through Poole-Frenkel emissionGood correlation coefficients (1198772) obtainedfrom ln(119869119881) versus radic119881 plots reveal that the mechanismresponsible for conduction in AgPcp-Si structures underforward bias conditions can be described by the Poole-Frenkel emission

4 Conclusion

In this work we have defined the synthesis and characteriza-tion of peripherally tetrasubstituted metal-free zinc cobalt

nickel and copper phthalocyanine derivatives These newfive compounds were characterized by various techniquesIn order to get more quantitative information about chargetransport mechanism and the usability of these compoundstomodify themain SBDparameters such as rectification ratioand the leakage current SBDs with the structure of AgPcp-Si were fabricated and characterized Our experimentalresults showed that charge transport in these compounds takeplace via different mechanism in reverse and forward biasconditions Results from this preliminary analysis indicatedthat the compounds can be considered among other candi-dates as a potential passivation layer for the new SBD diodeswith high rectification ratio and low leakage current

8 Journal of Chemistry

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

This study was supported by the Research Fund of YildizTechnical University (Project no 2016-01-02-DOP01)

Supplementary Materials

Figure S1 1H-NMR spectrum of compound 1 Figure S213C-NMR spectrum of compound 1 Figure S3 1H-NMRspectrum of compound 2 Figure S4 1H-NMR spectrum ofcompound 3 Figure S5 1H-NMR spectrum of compound 5(Supplementary Materials)

References

[1] N B McKeown Phthalocyanine Materials Synthesis Structureand Function Cambridge University Press Cambridge UK1998

[2] C C Leznoff A B P Lever P Stuzhin O Khelevina andB Berezin Phthalocyanines Properties and Applications VCHPublishers New York NY USA 1996

[3] M Bouvet P Gaudillat and J-M Suisse ldquoPhthalocyanine-based hybridmaterials for chemosensingrdquo Journal of Porphyrinsand Phthalocyanines vol 17 no 10 pp 913ndash919 2013

[4] C G Claessens U Hahn and T Torres ldquoPhthalocyaninesFrom outstanding electronic properties to emerging applica-tionsrdquoThe Chemical Record vol 8 no 2 pp 75ndash97 2008

[5] M Kraus S Richler A Opitz et al ldquoHigh-mobility copper-phthalocyanine field-effect transistors with tetratetracontanepassivation layer and organicmetal contactsrdquo Journal of AppliedPhysics vol 107 no 9 Article ID 094503 2010

[6] T Basova A Hassan M Durmus A G Gurek and V AhsenldquoLiquid crystalline metal phthalocyanines Structural organiza-tion on the substrate surfacerdquo Coordination Chemistry Reviewsvol 310 pp 131ndash153 2016

[7] D S Weiss and M Abkowitz ldquoAdvances in organic photocon-ductor technologyrdquo Chemical Reviews vol 110 no 1 pp 479ndash526 2010

[8] R Ao L Kummerl and D Haarer ldquoPresent limits of data stor-age using dye molecules in solid matricesrdquo Advanced Materialsvol 7 no 5 pp 495ndash499 1995

[9] M-E Ragoussi M Ince and T Torres ldquoRecent advances inphthalocyanine-based sensitizers for dye-sensitized solar cellsrdquoEuropean Journal of Organic Chemistry no 29 pp 6475ndash64892013

[10] Y Zhang X Cai Y Bian and J Jiang ldquoOrganic semiconduc-tors of phthalocyanine compounds for field effect transistors(FETs)rdquo in Functional Phthalocyanine Molecular Materials JJiang Ed vol 135 of Structure and Bonding pp 275ndash321Springer Berlin Germany 2010

[11] D Dini M J F Calvete and M Hanack ldquoNonlinear opticalmaterials for the smart filtering of optical radiationrdquo ChemicalReviews vol 116 no 22 pp 13043ndash13233 2016

[12] A Altindal S Abdurrahmanoglu M Bulut and OBekaroglu ldquoCharge transport mechanism in bis(double-deckerlutetium(III) phthalocyanine) (Lu2Pc4) thin filmrdquo SyntheticMetals vol 150 no 2 pp 181ndash187 2005

[13] T S Shafai and T D Anthopoulos ldquoJunction propertiesof nickel phthalocyanine thin film devices utilising indiuminjecting electrodesrdquoThin Solid Films vol 398-399 pp 361ndash3672001

[14] N N Halder P Biswas S Kundu and P Banerji ldquoAup-SiSchottky junction solar cell Effect of barrier height modifica-tion by InP quantum dotsrdquo Solar EnergyMaterials amp Solar Cellsvol 132 pp 230ndash236 2015

[15] E Rhoderick and R Williams MetalndashSemiconductor ContactsClarendon Oxford UK 2nd edition 1988

[16] S Yadav and S Ghosh ldquoAmorphous strontium titanate film asgate dielectric for higher performance and low voltage opera-tion of transparent and flexible organic field effect transistorrdquoACS Applied Materials amp Interfaces vol 8 no 16 pp 10436ndash10442 2016

[17] J Tardy M Erouel A L Deman et al ldquoOrganic thin filmtransistors with HfO2 high-k gate dielectric grown by anodicoxidation or deposited by sol-gelrdquo Microelectronics Reliabilityvol 47 no 2-3 pp 372ndash377 2007

[18] U Demirbas M Piskin B Barut R Bayrak M Durmusand H Kantekin ldquoMetal-free zinc(II) and lead(II) phthalo-cyanines functioning with 3-(2H-benzo[d][123]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups Synthesis and inves-tigation of photophysical and photochemical propertiesrdquo Syn-thetic Metals vol 220 pp 276ndash285 2016

[19] U Demirbas D Akyuz B Barut R Bayrak A Koca and HKantekin ldquoElectrochemical and spectroelectrochemical prop-erties of thiadiazole substitutedmetallo-phthalocyaninesrdquo Spec-trochimica Acta Part A Molecular and Biomolecular Spec-troscopy vol 153 pp 71ndash78 2016

[20] G Gumrukcu M U Ozgur A Altindal A R Ozkaya B Salihand O Bekaroglu ldquoSynthesis and electrochemical electricaland gas sensing properties of novel mononuclear metal-freeZn(II) Ni(II) Co(II) Cu(II) Lu(III) and double-decker Lu(III)phthalocyanines substituted with 2-(2H-123-benzotriazol- 2-yl)-4-(1133-tetramethylbutyl) phenoxyrdquo Synthetic Metals vol161 no 1-2 pp 112ndash123 2011

[21] O Koyun S Gorduk B Keskin A Cetinkaya A Koca andU Avciata ldquoMicrowave-assisted synthesis electrochemistryand spectroelectrochemistry of phthalocyanines bearing tetraterminal-alkynyl functionalities and click approachrdquo Polyhe-dron vol 113 pp 35ndash49 2016

[22] G K Karaoglan G Gumrukcu S Gorduk N Can and A GulldquoNovel homoleptic dimeric zinc(II) phthalocyanines as gatedielectric for OFET devicerdquo Synthetic Metals vol 230 pp 7ndash112017

[23] O F Yuksel N Tugluoglu H Safak and M Kus ldquoThemodification of Schottky barrier height of Aup-Si Schottkydevices by perylene-diimiderdquo Journal of Applied Physics vol 113no 4 Article ID 044507 2013

[24] H M J Al-Tarsquoii Y M Amin and V Periasamy ldquoCalculation ofthe electronic parameters of an AlDNAp-Si schottky barrierdiode influenced by alpha radiationrdquo Sensors vol 15 no 3 pp4810ndash4822 2015

[25] B Keskin A Altindal U Avciata and A Gul ldquoAC andDC Conduction processes in octakis[(4-tert-butylbenzylthio)-porphyrazinato]Cu(II) thin films with gold electrodesrdquo Bulletinof Materials Science vol 37 no 3 pp 461ndash468 2014

[26] B Keskin S Arda Ozturkcan and A Altindal ldquoUltrasound-assisted rapid one-pot synthesis characterization and electricalproperties of a 120573-aminoketone with a ferrocenyl moietyrdquoPolyhedron vol 69 pp 135ndash140 2014

Journal of Chemistry 5

4400

200

300

100

0

Inte

ns (

au)

mz

1600

1400

1300

1500

1700

1200

1100

1000

122

715

4

900

800

5

800

1000

400

600

200

0In

tens

(au

)

mz

1600

1400

1300

1500

1700

1200

1100

100090

0

800

122

779

31

215

078

31000

1200

200

400

600

800

0

Inte

ns (

au)

mz

1500

1600

1700

1400

1300

1200

1100

100090

0

123

451

22600

200

0

Inte

ns (

au)

1500

1400

1300

1200

1100

100090

0

800

700

600

117

131

5mz

400

6

400

500

200

300

100

0

Inte

ns (

au)

mz

1800

1400

1300

1600

1700

1500

1200

1100

1000

123

234

6

900

800

Figure 1 The MALDI-TOF MS spectra of the phthalocyanines (2ndash6)

and 675 nm for 6 in THF The shoulders of phthalocyanines3ndash6 were observed at 609 603 617 and 611 nm respectivelyFor the Q band of phthalocyanines the longer wavelengthabsorptions are owing to the monomeric species and shorterwavelengths (shoulders) are due to the aggregated species[2] The B bands were observed at 351 nm for 3 329 nmfor 4 327 nm for 5 and 341 nm for 6 For the metal-freephthalocyanine (2) a split Q band was observed at 701 and664 nm while B band was observed at 332 nm (Figure 2)

32 Characterization of SBDs A device without Pc interfacelayer was also fabricated in order to verify the efficacy of theinsertion of Pc layer on the charge transfer characteristic ofthe devices For comparison the room temperature currentdensity (119869) voltage characteristics of the devices are presentedin Figure 3 As is clear from Figure 3 all the devicesexhibit rectification behavior with different rectification ratio

between 7 for Agp-Si and 310 for Ag2P-Si structure atplusmn5 This results prove the good rectification performancefor the Pc layer inserted devices Leakage current is animportant factor influencing the performance of an SBDIt was found that the value of the leakage current den-sity for the Pc layer inserted devices varies between 229times 10minus7 Acm2 and 656 times 10minus7 Acm2 while the observedleakage current density was 138 times 10minus4 Acm2 for Agp-Sistructure It should be mentioned here that the observedlevel of leakage current density is significantly low whencompared with the reported values with similar structuresuch as AuPDIp-Si [23] and AlDNAp-Si [24] Schottkydevices This findings clearly show that the main perfor-mance parameters of a SBD such as rectification ratioand leakage current can be improved by modifying p-typesilicon surface with 2(3)9(10)16(17)23(24)-tetrakis-(23-dihydrobenzo[b][14]dioxin-2-yl)methoxyphthalocyanines

6 Journal of Chemistry

Wavelength (nm)800700600500400

234

56

00

02

04

06

Abso

rban

ce 08

10

12

14

Figure 2 UV-Vis spectra of phthalocyanines (2ndash6)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-SiAgp-Si

10minus10

10minus8

10minus6

10minus4

10minus2

J(A

＝Ｇ

2)

420

V (V)

minus2minus4

Figure 3 Room temperature 119869-119881 characteristics of the devices

Various models such as Fowler-Nordheim tunnelingPoole-Frenkel emission andOhmic and space charge limited(SCL) current have widely been used to understand thenature of the charge transport through an organic thin film[25ndash27] To investigate the dc conduction mechanism infabricated devices the obtained 119869-119881 data were replottedon double logarithmic scale for forward and reverse biasconditions in Figure 4

It will be clear from the analysis of the data presented inFigures 4(a) and 4(b) that there are two regions with differentslopes in double logarithmic 119869-119881 plots for both forwardand reverse bias conditions which is consistent with earlierreports on MetalPhthalocyanineMetal (MIM) structures

[28 29] A relatively small slope in 119869-119881 curves at low voltageregions is clear for both directions Special attention must begiven to interpreting the presented data in Figure 4 becausedifferent conduction mechanism can give rise to this typeof 119869-119881 characteristics A close analysis of the slopes of thecurves shown in Figure 4 indicates that the slopes of thecurves vary between 092 and 116 for reverse bias conditionswhich is indicative of the Ohmic conduction in this voltageregion On the other hand it was observed that the slopesof the 119869-119881 curves for forward bias vary between 215 and268 which cannot be considered in the framework of Ohmicconduction Therefore in order to identify the conductionmechanism taking place in AgPcp-Si structures the 119869-119881curves of the fabricated devices were analyzed separately forforward and reverse bias directions As mentioned beforethe reverse bias 119869-119881 characteristic of the devices at lowervoltage range can be explained by the Ohmic behavior ofthe device However a power law dependence in the formof 119869120572119881119904 with 119904 gt 2 reveals the presence of space chargelimited conductivity (SCLC) controlled by exponentiallydistributed trapping levels This type of 119869-119881 characteristichas been observed in some other Pc films such as copperphthalocyanine thin film [30] It should be mentioned herethat the reverse bias voltage at which the exponent 119904 deviatesfrom unity is nearly the same for all Pc modified devices Inorder to investigate whether our experimental data can beexplained using Poole-Frenkel emission we have plotted inFigure 5 ln(119869119881) versus 11988112 curves for all samples

In the case of Poole-Frenkel emission the relationshipbetween the current density and the applied voltage can beexpressed as given in [15]

119869 = 119860119881119889 exp(119902120593PF minus 120573PFradic119881119889119886119896119879 ) (1)

where 119860 is a fitting parameter 119889 is the thickness of the film119902120593PF is the required energy for an electron to escape from the

Journal of Chemistry 7

1 1001

V (V)

10minus11

10minus10

10minus9

10minus8

10minus7

10minus6

10minus5

10minus4

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(a)

1 1001

V (V)

10minus9

10minus8

10minus7

10minus6

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(b)

Figure 4 119869-119881 plots for forward (a) and reverse bias (b) conditions

minus12

minus15

minus18

minus21

minus24

ln(JV

)(A

＝Ｇ

2V)

04 08 12 16 20 2400

V12

(V)12

Agp-Si (R2= 0996)

Agp-Si (R2= 0998)

Agp-Si (R2= 0997)

Agp-Si (R2= 0996)

Agp-Si (R2= 0996)

Figure 5 Poole-Frenkel plots for the device investigated under forward bias condition

trap 119886 is the slope parameter and 120573PFradic119881 is barrier loweringAccording to (1) the plot of ln(119869119881) versus radic119881 should belinear if the charge transport takes place through Poole-Frenkel emissionGood correlation coefficients (1198772) obtainedfrom ln(119869119881) versus radic119881 plots reveal that the mechanismresponsible for conduction in AgPcp-Si structures underforward bias conditions can be described by the Poole-Frenkel emission

4 Conclusion

In this work we have defined the synthesis and characteriza-tion of peripherally tetrasubstituted metal-free zinc cobalt

nickel and copper phthalocyanine derivatives These newfive compounds were characterized by various techniquesIn order to get more quantitative information about chargetransport mechanism and the usability of these compoundstomodify themain SBDparameters such as rectification ratioand the leakage current SBDs with the structure of AgPcp-Si were fabricated and characterized Our experimentalresults showed that charge transport in these compounds takeplace via different mechanism in reverse and forward biasconditions Results from this preliminary analysis indicatedthat the compounds can be considered among other candi-dates as a potential passivation layer for the new SBD diodeswith high rectification ratio and low leakage current

8 Journal of Chemistry

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

This study was supported by the Research Fund of YildizTechnical University (Project no 2016-01-02-DOP01)

Supplementary Materials

Figure S1 1H-NMR spectrum of compound 1 Figure S213C-NMR spectrum of compound 1 Figure S3 1H-NMRspectrum of compound 2 Figure S4 1H-NMR spectrum ofcompound 3 Figure S5 1H-NMR spectrum of compound 5(Supplementary Materials)

References

[1] N B McKeown Phthalocyanine Materials Synthesis Structureand Function Cambridge University Press Cambridge UK1998

[2] C C Leznoff A B P Lever P Stuzhin O Khelevina andB Berezin Phthalocyanines Properties and Applications VCHPublishers New York NY USA 1996

[3] M Bouvet P Gaudillat and J-M Suisse ldquoPhthalocyanine-based hybridmaterials for chemosensingrdquo Journal of Porphyrinsand Phthalocyanines vol 17 no 10 pp 913ndash919 2013

[4] C G Claessens U Hahn and T Torres ldquoPhthalocyaninesFrom outstanding electronic properties to emerging applica-tionsrdquoThe Chemical Record vol 8 no 2 pp 75ndash97 2008

[5] M Kraus S Richler A Opitz et al ldquoHigh-mobility copper-phthalocyanine field-effect transistors with tetratetracontanepassivation layer and organicmetal contactsrdquo Journal of AppliedPhysics vol 107 no 9 Article ID 094503 2010

[6] T Basova A Hassan M Durmus A G Gurek and V AhsenldquoLiquid crystalline metal phthalocyanines Structural organiza-tion on the substrate surfacerdquo Coordination Chemistry Reviewsvol 310 pp 131ndash153 2016

[7] D S Weiss and M Abkowitz ldquoAdvances in organic photocon-ductor technologyrdquo Chemical Reviews vol 110 no 1 pp 479ndash526 2010

[8] R Ao L Kummerl and D Haarer ldquoPresent limits of data stor-age using dye molecules in solid matricesrdquo Advanced Materialsvol 7 no 5 pp 495ndash499 1995

[9] M-E Ragoussi M Ince and T Torres ldquoRecent advances inphthalocyanine-based sensitizers for dye-sensitized solar cellsrdquoEuropean Journal of Organic Chemistry no 29 pp 6475ndash64892013

[10] Y Zhang X Cai Y Bian and J Jiang ldquoOrganic semiconduc-tors of phthalocyanine compounds for field effect transistors(FETs)rdquo in Functional Phthalocyanine Molecular Materials JJiang Ed vol 135 of Structure and Bonding pp 275ndash321Springer Berlin Germany 2010

[11] D Dini M J F Calvete and M Hanack ldquoNonlinear opticalmaterials for the smart filtering of optical radiationrdquo ChemicalReviews vol 116 no 22 pp 13043ndash13233 2016

[12] A Altindal S Abdurrahmanoglu M Bulut and OBekaroglu ldquoCharge transport mechanism in bis(double-deckerlutetium(III) phthalocyanine) (Lu2Pc4) thin filmrdquo SyntheticMetals vol 150 no 2 pp 181ndash187 2005

[13] T S Shafai and T D Anthopoulos ldquoJunction propertiesof nickel phthalocyanine thin film devices utilising indiuminjecting electrodesrdquoThin Solid Films vol 398-399 pp 361ndash3672001

[14] N N Halder P Biswas S Kundu and P Banerji ldquoAup-SiSchottky junction solar cell Effect of barrier height modifica-tion by InP quantum dotsrdquo Solar EnergyMaterials amp Solar Cellsvol 132 pp 230ndash236 2015

[15] E Rhoderick and R Williams MetalndashSemiconductor ContactsClarendon Oxford UK 2nd edition 1988

[16] S Yadav and S Ghosh ldquoAmorphous strontium titanate film asgate dielectric for higher performance and low voltage opera-tion of transparent and flexible organic field effect transistorrdquoACS Applied Materials amp Interfaces vol 8 no 16 pp 10436ndash10442 2016

[17] J Tardy M Erouel A L Deman et al ldquoOrganic thin filmtransistors with HfO2 high-k gate dielectric grown by anodicoxidation or deposited by sol-gelrdquo Microelectronics Reliabilityvol 47 no 2-3 pp 372ndash377 2007

[18] U Demirbas M Piskin B Barut R Bayrak M Durmusand H Kantekin ldquoMetal-free zinc(II) and lead(II) phthalo-cyanines functioning with 3-(2H-benzo[d][123]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups Synthesis and inves-tigation of photophysical and photochemical propertiesrdquo Syn-thetic Metals vol 220 pp 276ndash285 2016

[19] U Demirbas D Akyuz B Barut R Bayrak A Koca and HKantekin ldquoElectrochemical and spectroelectrochemical prop-erties of thiadiazole substitutedmetallo-phthalocyaninesrdquo Spec-trochimica Acta Part A Molecular and Biomolecular Spec-troscopy vol 153 pp 71ndash78 2016

[20] G Gumrukcu M U Ozgur A Altindal A R Ozkaya B Salihand O Bekaroglu ldquoSynthesis and electrochemical electricaland gas sensing properties of novel mononuclear metal-freeZn(II) Ni(II) Co(II) Cu(II) Lu(III) and double-decker Lu(III)phthalocyanines substituted with 2-(2H-123-benzotriazol- 2-yl)-4-(1133-tetramethylbutyl) phenoxyrdquo Synthetic Metals vol161 no 1-2 pp 112ndash123 2011

[21] O Koyun S Gorduk B Keskin A Cetinkaya A Koca andU Avciata ldquoMicrowave-assisted synthesis electrochemistryand spectroelectrochemistry of phthalocyanines bearing tetraterminal-alkynyl functionalities and click approachrdquo Polyhe-dron vol 113 pp 35ndash49 2016

[22] G K Karaoglan G Gumrukcu S Gorduk N Can and A GulldquoNovel homoleptic dimeric zinc(II) phthalocyanines as gatedielectric for OFET devicerdquo Synthetic Metals vol 230 pp 7ndash112017

[23] O F Yuksel N Tugluoglu H Safak and M Kus ldquoThemodification of Schottky barrier height of Aup-Si Schottkydevices by perylene-diimiderdquo Journal of Applied Physics vol 113no 4 Article ID 044507 2013

[24] H M J Al-Tarsquoii Y M Amin and V Periasamy ldquoCalculation ofthe electronic parameters of an AlDNAp-Si schottky barrierdiode influenced by alpha radiationrdquo Sensors vol 15 no 3 pp4810ndash4822 2015

[25] B Keskin A Altindal U Avciata and A Gul ldquoAC andDC Conduction processes in octakis[(4-tert-butylbenzylthio)-porphyrazinato]Cu(II) thin films with gold electrodesrdquo Bulletinof Materials Science vol 37 no 3 pp 461ndash468 2014

[26] B Keskin S Arda Ozturkcan and A Altindal ldquoUltrasound-assisted rapid one-pot synthesis characterization and electricalproperties of a 120573-aminoketone with a ferrocenyl moietyrdquoPolyhedron vol 69 pp 135ndash140 2014

6 Journal of Chemistry

Wavelength (nm)800700600500400

234

56

00

02

04

06

Abso

rban

ce 08

10

12

14

Figure 2 UV-Vis spectra of phthalocyanines (2ndash6)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-SiAgp-Si

10minus10

10minus8

10minus6

10minus4

10minus2

J(A

＝Ｇ

2)

420

V (V)

minus2minus4

Figure 3 Room temperature 119869-119881 characteristics of the devices

Various models such as Fowler-Nordheim tunnelingPoole-Frenkel emission andOhmic and space charge limited(SCL) current have widely been used to understand thenature of the charge transport through an organic thin film[25ndash27] To investigate the dc conduction mechanism infabricated devices the obtained 119869-119881 data were replottedon double logarithmic scale for forward and reverse biasconditions in Figure 4

It will be clear from the analysis of the data presented inFigures 4(a) and 4(b) that there are two regions with differentslopes in double logarithmic 119869-119881 plots for both forwardand reverse bias conditions which is consistent with earlierreports on MetalPhthalocyanineMetal (MIM) structures

[28 29] A relatively small slope in 119869-119881 curves at low voltageregions is clear for both directions Special attention must begiven to interpreting the presented data in Figure 4 becausedifferent conduction mechanism can give rise to this typeof 119869-119881 characteristics A close analysis of the slopes of thecurves shown in Figure 4 indicates that the slopes of thecurves vary between 092 and 116 for reverse bias conditionswhich is indicative of the Ohmic conduction in this voltageregion On the other hand it was observed that the slopesof the 119869-119881 curves for forward bias vary between 215 and268 which cannot be considered in the framework of Ohmicconduction Therefore in order to identify the conductionmechanism taking place in AgPcp-Si structures the 119869-119881curves of the fabricated devices were analyzed separately forforward and reverse bias directions As mentioned beforethe reverse bias 119869-119881 characteristic of the devices at lowervoltage range can be explained by the Ohmic behavior ofthe device However a power law dependence in the formof 119869120572119881119904 with 119904 gt 2 reveals the presence of space chargelimited conductivity (SCLC) controlled by exponentiallydistributed trapping levels This type of 119869-119881 characteristichas been observed in some other Pc films such as copperphthalocyanine thin film [30] It should be mentioned herethat the reverse bias voltage at which the exponent 119904 deviatesfrom unity is nearly the same for all Pc modified devices Inorder to investigate whether our experimental data can beexplained using Poole-Frenkel emission we have plotted inFigure 5 ln(119869119881) versus 11988112 curves for all samples

In the case of Poole-Frenkel emission the relationshipbetween the current density and the applied voltage can beexpressed as given in [15]

119869 = 119860119881119889 exp(119902120593PF minus 120573PFradic119881119889119886119896119879 ) (1)

where 119860 is a fitting parameter 119889 is the thickness of the film119902120593PF is the required energy for an electron to escape from the

Journal of Chemistry 7

1 1001

V (V)

10minus11

10minus10

10minus9

10minus8

10minus7

10minus6

10minus5

10minus4

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(a)

1 1001

V (V)

10minus9

10minus8

10minus7

10minus6

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(b)

Figure 4 119869-119881 plots for forward (a) and reverse bias (b) conditions

minus12

minus15

minus18

minus21

minus24

ln(JV

)(A

＝Ｇ

2V)

04 08 12 16 20 2400

V12

(V)12

Agp-Si (R2= 0996)

Agp-Si (R2= 0998)

Agp-Si (R2= 0997)

Agp-Si (R2= 0996)

Agp-Si (R2= 0996)

Figure 5 Poole-Frenkel plots for the device investigated under forward bias condition

trap 119886 is the slope parameter and 120573PFradic119881 is barrier loweringAccording to (1) the plot of ln(119869119881) versus radic119881 should belinear if the charge transport takes place through Poole-Frenkel emissionGood correlation coefficients (1198772) obtainedfrom ln(119869119881) versus radic119881 plots reveal that the mechanismresponsible for conduction in AgPcp-Si structures underforward bias conditions can be described by the Poole-Frenkel emission

4 Conclusion

In this work we have defined the synthesis and characteriza-tion of peripherally tetrasubstituted metal-free zinc cobalt

nickel and copper phthalocyanine derivatives These newfive compounds were characterized by various techniquesIn order to get more quantitative information about chargetransport mechanism and the usability of these compoundstomodify themain SBDparameters such as rectification ratioand the leakage current SBDs with the structure of AgPcp-Si were fabricated and characterized Our experimentalresults showed that charge transport in these compounds takeplace via different mechanism in reverse and forward biasconditions Results from this preliminary analysis indicatedthat the compounds can be considered among other candi-dates as a potential passivation layer for the new SBD diodeswith high rectification ratio and low leakage current

8 Journal of Chemistry

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

This study was supported by the Research Fund of YildizTechnical University (Project no 2016-01-02-DOP01)

Supplementary Materials

Figure S1 1H-NMR spectrum of compound 1 Figure S213C-NMR spectrum of compound 1 Figure S3 1H-NMRspectrum of compound 2 Figure S4 1H-NMR spectrum ofcompound 3 Figure S5 1H-NMR spectrum of compound 5(Supplementary Materials)

References

[1] N B McKeown Phthalocyanine Materials Synthesis Structureand Function Cambridge University Press Cambridge UK1998

[2] C C Leznoff A B P Lever P Stuzhin O Khelevina andB Berezin Phthalocyanines Properties and Applications VCHPublishers New York NY USA 1996

[3] M Bouvet P Gaudillat and J-M Suisse ldquoPhthalocyanine-based hybridmaterials for chemosensingrdquo Journal of Porphyrinsand Phthalocyanines vol 17 no 10 pp 913ndash919 2013

[4] C G Claessens U Hahn and T Torres ldquoPhthalocyaninesFrom outstanding electronic properties to emerging applica-tionsrdquoThe Chemical Record vol 8 no 2 pp 75ndash97 2008

[5] M Kraus S Richler A Opitz et al ldquoHigh-mobility copper-phthalocyanine field-effect transistors with tetratetracontanepassivation layer and organicmetal contactsrdquo Journal of AppliedPhysics vol 107 no 9 Article ID 094503 2010

[6] T Basova A Hassan M Durmus A G Gurek and V AhsenldquoLiquid crystalline metal phthalocyanines Structural organiza-tion on the substrate surfacerdquo Coordination Chemistry Reviewsvol 310 pp 131ndash153 2016

[7] D S Weiss and M Abkowitz ldquoAdvances in organic photocon-ductor technologyrdquo Chemical Reviews vol 110 no 1 pp 479ndash526 2010

[8] R Ao L Kummerl and D Haarer ldquoPresent limits of data stor-age using dye molecules in solid matricesrdquo Advanced Materialsvol 7 no 5 pp 495ndash499 1995

[9] M-E Ragoussi M Ince and T Torres ldquoRecent advances inphthalocyanine-based sensitizers for dye-sensitized solar cellsrdquoEuropean Journal of Organic Chemistry no 29 pp 6475ndash64892013

[10] Y Zhang X Cai Y Bian and J Jiang ldquoOrganic semiconduc-tors of phthalocyanine compounds for field effect transistors(FETs)rdquo in Functional Phthalocyanine Molecular Materials JJiang Ed vol 135 of Structure and Bonding pp 275ndash321Springer Berlin Germany 2010

[11] D Dini M J F Calvete and M Hanack ldquoNonlinear opticalmaterials for the smart filtering of optical radiationrdquo ChemicalReviews vol 116 no 22 pp 13043ndash13233 2016

[12] A Altindal S Abdurrahmanoglu M Bulut and OBekaroglu ldquoCharge transport mechanism in bis(double-deckerlutetium(III) phthalocyanine) (Lu2Pc4) thin filmrdquo SyntheticMetals vol 150 no 2 pp 181ndash187 2005

[13] T S Shafai and T D Anthopoulos ldquoJunction propertiesof nickel phthalocyanine thin film devices utilising indiuminjecting electrodesrdquoThin Solid Films vol 398-399 pp 361ndash3672001

[14] N N Halder P Biswas S Kundu and P Banerji ldquoAup-SiSchottky junction solar cell Effect of barrier height modifica-tion by InP quantum dotsrdquo Solar EnergyMaterials amp Solar Cellsvol 132 pp 230ndash236 2015

[15] E Rhoderick and R Williams MetalndashSemiconductor ContactsClarendon Oxford UK 2nd edition 1988

[16] S Yadav and S Ghosh ldquoAmorphous strontium titanate film asgate dielectric for higher performance and low voltage opera-tion of transparent and flexible organic field effect transistorrdquoACS Applied Materials amp Interfaces vol 8 no 16 pp 10436ndash10442 2016

[17] J Tardy M Erouel A L Deman et al ldquoOrganic thin filmtransistors with HfO2 high-k gate dielectric grown by anodicoxidation or deposited by sol-gelrdquo Microelectronics Reliabilityvol 47 no 2-3 pp 372ndash377 2007

[18] U Demirbas M Piskin B Barut R Bayrak M Durmusand H Kantekin ldquoMetal-free zinc(II) and lead(II) phthalo-cyanines functioning with 3-(2H-benzo[d][123]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups Synthesis and inves-tigation of photophysical and photochemical propertiesrdquo Syn-thetic Metals vol 220 pp 276ndash285 2016

[19] U Demirbas D Akyuz B Barut R Bayrak A Koca and HKantekin ldquoElectrochemical and spectroelectrochemical prop-erties of thiadiazole substitutedmetallo-phthalocyaninesrdquo Spec-trochimica Acta Part A Molecular and Biomolecular Spec-troscopy vol 153 pp 71ndash78 2016

[20] G Gumrukcu M U Ozgur A Altindal A R Ozkaya B Salihand O Bekaroglu ldquoSynthesis and electrochemical electricaland gas sensing properties of novel mononuclear metal-freeZn(II) Ni(II) Co(II) Cu(II) Lu(III) and double-decker Lu(III)phthalocyanines substituted with 2-(2H-123-benzotriazol- 2-yl)-4-(1133-tetramethylbutyl) phenoxyrdquo Synthetic Metals vol161 no 1-2 pp 112ndash123 2011

[21] O Koyun S Gorduk B Keskin A Cetinkaya A Koca andU Avciata ldquoMicrowave-assisted synthesis electrochemistryand spectroelectrochemistry of phthalocyanines bearing tetraterminal-alkynyl functionalities and click approachrdquo Polyhe-dron vol 113 pp 35ndash49 2016

[22] G K Karaoglan G Gumrukcu S Gorduk N Can and A GulldquoNovel homoleptic dimeric zinc(II) phthalocyanines as gatedielectric for OFET devicerdquo Synthetic Metals vol 230 pp 7ndash112017

[23] O F Yuksel N Tugluoglu H Safak and M Kus ldquoThemodification of Schottky barrier height of Aup-Si Schottkydevices by perylene-diimiderdquo Journal of Applied Physics vol 113no 4 Article ID 044507 2013

[24] H M J Al-Tarsquoii Y M Amin and V Periasamy ldquoCalculation ofthe electronic parameters of an AlDNAp-Si schottky barrierdiode influenced by alpha radiationrdquo Sensors vol 15 no 3 pp4810ndash4822 2015

[25] B Keskin A Altindal U Avciata and A Gul ldquoAC andDC Conduction processes in octakis[(4-tert-butylbenzylthio)-porphyrazinato]Cu(II) thin films with gold electrodesrdquo Bulletinof Materials Science vol 37 no 3 pp 461ndash468 2014

[26] B Keskin S Arda Ozturkcan and A Altindal ldquoUltrasound-assisted rapid one-pot synthesis characterization and electricalproperties of a 120573-aminoketone with a ferrocenyl moietyrdquoPolyhedron vol 69 pp 135ndash140 2014

Journal of Chemistry 7

1 1001

V (V)

10minus11

10minus10

10minus9

10minus8

10minus7

10minus6

10minus5

10minus4

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(a)

1 1001

V (V)

10minus9

10minus8

10minus7

10minus6

J(A

＝Ｇ

2)

Agp-SiAgp-SiAgp-Si

Agp-SiAgp-Si

(b)

Figure 4 119869-119881 plots for forward (a) and reverse bias (b) conditions

minus12

minus15

minus18

minus21

minus24

ln(JV

)(A

＝Ｇ

2V)

04 08 12 16 20 2400

V12

(V)12

Agp-Si (R2= 0996)

Agp-Si (R2= 0998)

Agp-Si (R2= 0997)

Agp-Si (R2= 0996)

Agp-Si (R2= 0996)

Figure 5 Poole-Frenkel plots for the device investigated under forward bias condition

trap 119886 is the slope parameter and 120573PFradic119881 is barrier loweringAccording to (1) the plot of ln(119869119881) versus radic119881 should belinear if the charge transport takes place through Poole-Frenkel emissionGood correlation coefficients (1198772) obtainedfrom ln(119869119881) versus radic119881 plots reveal that the mechanismresponsible for conduction in AgPcp-Si structures underforward bias conditions can be described by the Poole-Frenkel emission

4 Conclusion

In this work we have defined the synthesis and characteriza-tion of peripherally tetrasubstituted metal-free zinc cobalt

nickel and copper phthalocyanine derivatives These newfive compounds were characterized by various techniquesIn order to get more quantitative information about chargetransport mechanism and the usability of these compoundstomodify themain SBDparameters such as rectification ratioand the leakage current SBDs with the structure of AgPcp-Si were fabricated and characterized Our experimentalresults showed that charge transport in these compounds takeplace via different mechanism in reverse and forward biasconditions Results from this preliminary analysis indicatedthat the compounds can be considered among other candi-dates as a potential passivation layer for the new SBD diodeswith high rectification ratio and low leakage current

8 Journal of Chemistry

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

This study was supported by the Research Fund of YildizTechnical University (Project no 2016-01-02-DOP01)

Supplementary Materials

Figure S1 1H-NMR spectrum of compound 1 Figure S213C-NMR spectrum of compound 1 Figure S3 1H-NMRspectrum of compound 2 Figure S4 1H-NMR spectrum ofcompound 3 Figure S5 1H-NMR spectrum of compound 5(Supplementary Materials)

References

[1] N B McKeown Phthalocyanine Materials Synthesis Structureand Function Cambridge University Press Cambridge UK1998

[2] C C Leznoff A B P Lever P Stuzhin O Khelevina andB Berezin Phthalocyanines Properties and Applications VCHPublishers New York NY USA 1996

[3] M Bouvet P Gaudillat and J-M Suisse ldquoPhthalocyanine-based hybridmaterials for chemosensingrdquo Journal of Porphyrinsand Phthalocyanines vol 17 no 10 pp 913ndash919 2013

[4] C G Claessens U Hahn and T Torres ldquoPhthalocyaninesFrom outstanding electronic properties to emerging applica-tionsrdquoThe Chemical Record vol 8 no 2 pp 75ndash97 2008

[5] M Kraus S Richler A Opitz et al ldquoHigh-mobility copper-phthalocyanine field-effect transistors with tetratetracontanepassivation layer and organicmetal contactsrdquo Journal of AppliedPhysics vol 107 no 9 Article ID 094503 2010

[6] T Basova A Hassan M Durmus A G Gurek and V AhsenldquoLiquid crystalline metal phthalocyanines Structural organiza-tion on the substrate surfacerdquo Coordination Chemistry Reviewsvol 310 pp 131ndash153 2016

[7] D S Weiss and M Abkowitz ldquoAdvances in organic photocon-ductor technologyrdquo Chemical Reviews vol 110 no 1 pp 479ndash526 2010

[8] R Ao L Kummerl and D Haarer ldquoPresent limits of data stor-age using dye molecules in solid matricesrdquo Advanced Materialsvol 7 no 5 pp 495ndash499 1995

[9] M-E Ragoussi M Ince and T Torres ldquoRecent advances inphthalocyanine-based sensitizers for dye-sensitized solar cellsrdquoEuropean Journal of Organic Chemistry no 29 pp 6475ndash64892013

[10] Y Zhang X Cai Y Bian and J Jiang ldquoOrganic semiconduc-tors of phthalocyanine compounds for field effect transistors(FETs)rdquo in Functional Phthalocyanine Molecular Materials JJiang Ed vol 135 of Structure and Bonding pp 275ndash321Springer Berlin Germany 2010

[11] D Dini M J F Calvete and M Hanack ldquoNonlinear opticalmaterials for the smart filtering of optical radiationrdquo ChemicalReviews vol 116 no 22 pp 13043ndash13233 2016

[12] A Altindal S Abdurrahmanoglu M Bulut and OBekaroglu ldquoCharge transport mechanism in bis(double-deckerlutetium(III) phthalocyanine) (Lu2Pc4) thin filmrdquo SyntheticMetals vol 150 no 2 pp 181ndash187 2005

[13] T S Shafai and T D Anthopoulos ldquoJunction propertiesof nickel phthalocyanine thin film devices utilising indiuminjecting electrodesrdquoThin Solid Films vol 398-399 pp 361ndash3672001

[14] N N Halder P Biswas S Kundu and P Banerji ldquoAup-SiSchottky junction solar cell Effect of barrier height modifica-tion by InP quantum dotsrdquo Solar EnergyMaterials amp Solar Cellsvol 132 pp 230ndash236 2015

[15] E Rhoderick and R Williams MetalndashSemiconductor ContactsClarendon Oxford UK 2nd edition 1988

[16] S Yadav and S Ghosh ldquoAmorphous strontium titanate film asgate dielectric for higher performance and low voltage opera-tion of transparent and flexible organic field effect transistorrdquoACS Applied Materials amp Interfaces vol 8 no 16 pp 10436ndash10442 2016

[17] J Tardy M Erouel A L Deman et al ldquoOrganic thin filmtransistors with HfO2 high-k gate dielectric grown by anodicoxidation or deposited by sol-gelrdquo Microelectronics Reliabilityvol 47 no 2-3 pp 372ndash377 2007

[18] U Demirbas M Piskin B Barut R Bayrak M Durmusand H Kantekin ldquoMetal-free zinc(II) and lead(II) phthalo-cyanines functioning with 3-(2H-benzo[d][123]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups Synthesis and inves-tigation of photophysical and photochemical propertiesrdquo Syn-thetic Metals vol 220 pp 276ndash285 2016

[19] U Demirbas D Akyuz B Barut R Bayrak A Koca and HKantekin ldquoElectrochemical and spectroelectrochemical prop-erties of thiadiazole substitutedmetallo-phthalocyaninesrdquo Spec-trochimica Acta Part A Molecular and Biomolecular Spec-troscopy vol 153 pp 71ndash78 2016

[20] G Gumrukcu M U Ozgur A Altindal A R Ozkaya B Salihand O Bekaroglu ldquoSynthesis and electrochemical electricaland gas sensing properties of novel mononuclear metal-freeZn(II) Ni(II) Co(II) Cu(II) Lu(III) and double-decker Lu(III)phthalocyanines substituted with 2-(2H-123-benzotriazol- 2-yl)-4-(1133-tetramethylbutyl) phenoxyrdquo Synthetic Metals vol161 no 1-2 pp 112ndash123 2011

[21] O Koyun S Gorduk B Keskin A Cetinkaya A Koca andU Avciata ldquoMicrowave-assisted synthesis electrochemistryand spectroelectrochemistry of phthalocyanines bearing tetraterminal-alkynyl functionalities and click approachrdquo Polyhe-dron vol 113 pp 35ndash49 2016

[22] G K Karaoglan G Gumrukcu S Gorduk N Can and A GulldquoNovel homoleptic dimeric zinc(II) phthalocyanines as gatedielectric for OFET devicerdquo Synthetic Metals vol 230 pp 7ndash112017

[23] O F Yuksel N Tugluoglu H Safak and M Kus ldquoThemodification of Schottky barrier height of Aup-Si Schottkydevices by perylene-diimiderdquo Journal of Applied Physics vol 113no 4 Article ID 044507 2013

[24] H M J Al-Tarsquoii Y M Amin and V Periasamy ldquoCalculation ofthe electronic parameters of an AlDNAp-Si schottky barrierdiode influenced by alpha radiationrdquo Sensors vol 15 no 3 pp4810ndash4822 2015

[25] B Keskin A Altindal U Avciata and A Gul ldquoAC andDC Conduction processes in octakis[(4-tert-butylbenzylthio)-porphyrazinato]Cu(II) thin films with gold electrodesrdquo Bulletinof Materials Science vol 37 no 3 pp 461ndash468 2014

[26] B Keskin S Arda Ozturkcan and A Altindal ldquoUltrasound-assisted rapid one-pot synthesis characterization and electricalproperties of a 120573-aminoketone with a ferrocenyl moietyrdquoPolyhedron vol 69 pp 135ndash140 2014

8 Journal of Chemistry

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

This study was supported by the Research Fund of YildizTechnical University (Project no 2016-01-02-DOP01)

Supplementary Materials

Figure S1 1H-NMR spectrum of compound 1 Figure S213C-NMR spectrum of compound 1 Figure S3 1H-NMRspectrum of compound 2 Figure S4 1H-NMR spectrum ofcompound 3 Figure S5 1H-NMR spectrum of compound 5(Supplementary Materials)

References

[1] N B McKeown Phthalocyanine Materials Synthesis Structureand Function Cambridge University Press Cambridge UK1998

[2] C C Leznoff A B P Lever P Stuzhin O Khelevina andB Berezin Phthalocyanines Properties and Applications VCHPublishers New York NY USA 1996

[3] M Bouvet P Gaudillat and J-M Suisse ldquoPhthalocyanine-based hybridmaterials for chemosensingrdquo Journal of Porphyrinsand Phthalocyanines vol 17 no 10 pp 913ndash919 2013

[4] C G Claessens U Hahn and T Torres ldquoPhthalocyaninesFrom outstanding electronic properties to emerging applica-tionsrdquoThe Chemical Record vol 8 no 2 pp 75ndash97 2008

[5] M Kraus S Richler A Opitz et al ldquoHigh-mobility copper-phthalocyanine field-effect transistors with tetratetracontanepassivation layer and organicmetal contactsrdquo Journal of AppliedPhysics vol 107 no 9 Article ID 094503 2010

[6] T Basova A Hassan M Durmus A G Gurek and V AhsenldquoLiquid crystalline metal phthalocyanines Structural organiza-tion on the substrate surfacerdquo Coordination Chemistry Reviewsvol 310 pp 131ndash153 2016

[7] D S Weiss and M Abkowitz ldquoAdvances in organic photocon-ductor technologyrdquo Chemical Reviews vol 110 no 1 pp 479ndash526 2010

[8] R Ao L Kummerl and D Haarer ldquoPresent limits of data stor-age using dye molecules in solid matricesrdquo Advanced Materialsvol 7 no 5 pp 495ndash499 1995

[9] M-E Ragoussi M Ince and T Torres ldquoRecent advances inphthalocyanine-based sensitizers for dye-sensitized solar cellsrdquoEuropean Journal of Organic Chemistry no 29 pp 6475ndash64892013

[10] Y Zhang X Cai Y Bian and J Jiang ldquoOrganic semiconduc-tors of phthalocyanine compounds for field effect transistors(FETs)rdquo in Functional Phthalocyanine Molecular Materials JJiang Ed vol 135 of Structure and Bonding pp 275ndash321Springer Berlin Germany 2010

[11] D Dini M J F Calvete and M Hanack ldquoNonlinear opticalmaterials for the smart filtering of optical radiationrdquo ChemicalReviews vol 116 no 22 pp 13043ndash13233 2016

[12] A Altindal S Abdurrahmanoglu M Bulut and OBekaroglu ldquoCharge transport mechanism in bis(double-deckerlutetium(III) phthalocyanine) (Lu2Pc4) thin filmrdquo SyntheticMetals vol 150 no 2 pp 181ndash187 2005

[13] T S Shafai and T D Anthopoulos ldquoJunction propertiesof nickel phthalocyanine thin film devices utilising indiuminjecting electrodesrdquoThin Solid Films vol 398-399 pp 361ndash3672001

[14] N N Halder P Biswas S Kundu and P Banerji ldquoAup-SiSchottky junction solar cell Effect of barrier height modifica-tion by InP quantum dotsrdquo Solar EnergyMaterials amp Solar Cellsvol 132 pp 230ndash236 2015

[15] E Rhoderick and R Williams MetalndashSemiconductor ContactsClarendon Oxford UK 2nd edition 1988

[16] S Yadav and S Ghosh ldquoAmorphous strontium titanate film asgate dielectric for higher performance and low voltage opera-tion of transparent and flexible organic field effect transistorrdquoACS Applied Materials amp Interfaces vol 8 no 16 pp 10436ndash10442 2016

[17] J Tardy M Erouel A L Deman et al ldquoOrganic thin filmtransistors with HfO2 high-k gate dielectric grown by anodicoxidation or deposited by sol-gelrdquo Microelectronics Reliabilityvol 47 no 2-3 pp 372ndash377 2007

[18] U Demirbas M Piskin B Barut R Bayrak M Durmusand H Kantekin ldquoMetal-free zinc(II) and lead(II) phthalo-cyanines functioning with 3-(2H-benzo[d][123]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups Synthesis and inves-tigation of photophysical and photochemical propertiesrdquo Syn-thetic Metals vol 220 pp 276ndash285 2016

[19] U Demirbas D Akyuz B Barut R Bayrak A Koca and HKantekin ldquoElectrochemical and spectroelectrochemical prop-erties of thiadiazole substitutedmetallo-phthalocyaninesrdquo Spec-trochimica Acta Part A Molecular and Biomolecular Spec-troscopy vol 153 pp 71ndash78 2016

[20] G Gumrukcu M U Ozgur A Altindal A R Ozkaya B Salihand O Bekaroglu ldquoSynthesis and electrochemical electricaland gas sensing properties of novel mononuclear metal-freeZn(II) Ni(II) Co(II) Cu(II) Lu(III) and double-decker Lu(III)phthalocyanines substituted with 2-(2H-123-benzotriazol- 2-yl)-4-(1133-tetramethylbutyl) phenoxyrdquo Synthetic Metals vol161 no 1-2 pp 112ndash123 2011

[21] O Koyun S Gorduk B Keskin A Cetinkaya A Koca andU Avciata ldquoMicrowave-assisted synthesis electrochemistryand spectroelectrochemistry of phthalocyanines bearing tetraterminal-alkynyl functionalities and click approachrdquo Polyhe-dron vol 113 pp 35ndash49 2016

[22] G K Karaoglan G Gumrukcu S Gorduk N Can and A GulldquoNovel homoleptic dimeric zinc(II) phthalocyanines as gatedielectric for OFET devicerdquo Synthetic Metals vol 230 pp 7ndash112017

[23] O F Yuksel N Tugluoglu H Safak and M Kus ldquoThemodification of Schottky barrier height of Aup-Si Schottkydevices by perylene-diimiderdquo Journal of Applied Physics vol 113no 4 Article ID 044507 2013

[24] H M J Al-Tarsquoii Y M Amin and V Periasamy ldquoCalculation ofthe electronic parameters of an AlDNAp-Si schottky barrierdiode influenced by alpha radiationrdquo Sensors vol 15 no 3 pp4810ndash4822 2015

[25] B Keskin A Altindal U Avciata and A Gul ldquoAC andDC Conduction processes in octakis[(4-tert-butylbenzylthio)-porphyrazinato]Cu(II) thin films with gold electrodesrdquo Bulletinof Materials Science vol 37 no 3 pp 461ndash468 2014

[26] B Keskin S Arda Ozturkcan and A Altindal ldquoUltrasound-assisted rapid one-pot synthesis characterization and electricalproperties of a 120573-aminoketone with a ferrocenyl moietyrdquoPolyhedron vol 69 pp 135ndash140 2014

Journal of Chemistry 9

[27] F-C Chiu ldquoA review on conduction mechanisms in dielectricfilmsrdquo Advances in Materials Science and Engineering vol 2014Article ID 578168 18 pages 2014

[28] T G Abdel Malik and R M Abdel-Latif ldquoOhmic and space-charge limited conduction in cobalt phthalocyanine thin filmsrdquoThin Solid Films vol 305 no 1-2 pp 336ndash340 1997

[29] A C Varghese and C S Menon ldquoElectrical properties of nickelphthalocyanine thin films using gold and lead electrodesrdquoJournal of Materials Science Materials in Electronics vol 17 no2 pp 149ndash153 2006

[30] A K Hassan and R D Gould ldquoThe electrical properties ofcopper phthalocyanine thin films using indium electrodesrdquoJournal of Physics D Applied Physics vol 22 no 8 pp 1162ndash11681989

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of