research article high efficiency of dye-sensitized solar cells...

Hindawi Publishing CorporationInternational Journal of PhotoenergyVolume 2013 Article ID 250397 6 pageshttpdxdoiorg1011552013250397

Research ArticleHigh Efficiency of Dye-Sensitized Solar Cells Based onRuthenium and Metal-Free Dyes

Che-Lung Lee1 Wen-Hsi Lee1 and Cheng-Hsien Yang2

1 Department of Electrical Engineering Nation Cheng Kung University No 1 Daxue Rd East Dist Tainan City 70101 Taiwan2Nano-Powder and Thin Film Technology Center ITRI South Room 603 Buildig R2 No 31 Gongye 2nd Road Annan DistrictTainan 70955 Taiwan

Correspondence should be addressed to Cheng-Hsien Yang jasonyangfusol-materialcom

Received 8 September 2013 Accepted 12 October 2013

Academic Editor Teen-Hang Meen

Copyright copy 2013 Che-Lung Lee 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

The influence of using different concentrations of triazoloisoquinoline based small molecule as coadsorbent to modify themonolayer of a TiO

2semiconductor on the performance of a dye-sensitized solar cell is studied The co-adsorbent significantly

enhances the open-circuit photovoltage (119881oc) the short circuit photocurrent density (119869sc) the solar energy conversion efficiency(gt 120578) The co-adsorbent 4L is applied successfully to prepare an insulating molecular layer with N719 and achieve high energyconversion efficiency as high as 883 at 100mWcmminus2 and AM 15 at 1 to 025 (N719 co-adsorbent) molar ratio The resultingefficiency is about 6 higher than that of a nonadditive device The result shows that the organic small molecule 4L (2-cyano-3-(5-(4-(3-oxo-[124]triazolo[34-a]isoquinoline-2(3H)-yl)phenyl)thiophene-2-yl)acrylic acid) is the promising candidates forimprovement of the performance of dye-sensitized solar cell

1 Introduction

Dye-sensitized solar cells have attracted considerable aca-demic and industrial research interest since Regan andGratzelrsquos report in 1991 [1] Usually these cells consist ofa working electrode which is coated with a dye-sensitizedmesoporous film of nanocrystalline particles of TiO

2 a Pt-

coated counterelectrode and an electrolyte containing asuitable redox couple The function of such devices is basedon the electron injection from the photoexcited state ofthe dye molecule into the conduction band of the TiO

2

followed by regeneration of the dye by an iodidetriiodideredox couple Typically high power conversion efficiencies(120578) of more than 11 have been achieved by using rutheniumcomplex and acetonitrile based electrolytes [2] Howeverorganic additives play a key role in the characteristics of bothelectrolytes and devices and have been explored extensivelywith regard to improving the efficiency of DSSC [3ndash5]

A few reports have described the use of organic additivesfor a compact layer comprised of the dye and coadsorbent

[6 7] Chenodeoxycholic acid (DCA) is frequently added tothe dye solution to enhance the open-circuit photovoltage(119881oc) the short circuit photocurrent density (119869sc) and theefficiency (120578) of DSSC [8 9] The119881oc 119869sc and FF of the DSSCare affected by DCA due to the suppression of dark currentat the semiconductorelectrolyte junction since DCA blocksthe surface states Ti(IV) ions that are active in the chargetransfer [10] Due to the insulatingmolecular layer the chargerecombination process can be shielded and this increases the119881oc 119869sc and 120578 Several approaches have been developed forthis purpose such as the use of pyridinium additives [11]pyrimidine additives [12] dipolar carboxylic acid derivatives[13] zwitterionic coadsorbents [14] and guanidinium cations[4] In this paper we synthesize a new triazoloisoquinoline-based organic small molecule used as co-adsorbents tomodify the monolayer of a TiO

2semiconductor We discuss

the concentration effect of co-adsorbents and investigate thepossibility of using triazoloisoquinoline-based organic smallmolecule as co-adsorbents in DSSC

2 International Journal of Photoenergy

2 Experimental

21 General Procedure for Preparation of Solar CellsFluorine-doped tin oxide (FTO 10Ω squareminus1) glass plateswere cleaned using detergent solution water and ethanol inan ultrasonic bath overnight The screen-printing procedurewas repeated with TiO

2paste (sim15ndash20 nm colloidal particles

Ti-Nanoxide T series Solaronix SA) to obtain a transparentnanocrystalline film of thickness around 12 120583m The 100 nmcolloidal particles were prepared in a basic environmentaccording to the literature [15] and dispersed in 120572-terpineolwith ethyl cellulose for scattering TiO

2paste A scattering

layer around 4 120583m was deposited by using this scatteringTiO2paste and a final thickness of 16120583m was attained

The TiO2electrodes were gradually annealed at 450∘C for

30min in an oven in an air atmosphere After sintering theelectrodes were further treated with 02M TiCl

4aqueous

solution at room temperature for 12 h then washed withwater and ethanol and annealed at 450∘C for 30min Whenthe temperature decreased to 70∘C after sintering theelectrodes were immersed into dye solution which included05mM N719 and different concentrations of co-adsorbentin tert-butanolacetonitrile (AN) (1 1 in volume) The dyesolutions were kept at 25∘C for more than 18 h to allow thedye to adsorb to the TiO

2surface After the adsorption of

the dyes the electrode was rinsed with the same solventThe dye-loaded TiO

2film as the working electrode and

Pt-coated TCO as the counterelectrode (about 20 nm) wereseparated by a hot-melt Surlyn sheet (25120583m) and sealedtogether by pressing them under heat The electrolyteswere introduced into the gap between the working andcounterelectrodes from two holes predrilled on the back ofthe counterelectrode Finally the two holes were sealed witha Surlyn film covering a thin glass slide under heat The cellswere evaluated by using 06M [BMI][I] 01MGuNCS 03MI2 and 05M TBP in a ANVN (8515 vv) solvent as the

redox electrolyte

22 Photovoltaic Measurement The current-voltage (119868-119881)characteristics in the dark and under illumination weremeasured with a Keithley 2400 sourcemeter The photocur-rent was measured in a nitrogen-filled glove box under asolar simulator (Oriel 96000 150W) with AM 15G-filteredillumination (100mWcmminus2)The spectra-mismatch factor ofthe simulated solar irradiation was corrected using a Schottvisible-color glass-filtered (KG5 color filter) Si diode (Hama-matsu S1133) The active area of the device was 025 cm2

23 Dye Loading Measurement The TiO2films were put

into the dye solution (N719 3 times 10minus4M in tert-butanol andacetonitrile 1 1 vv) for 24 h Subsequently the TiO

2films

were washed with acetonitrile after the adsorption processand then dried in N

2flow Dye loading measurements were

conducted by desorbing the dye molecules from the dye-anchored films in NaOH ethanolic solution The loadingamountwas calculated from the absorbance of the completelydesorbed dye solutions by the spectrophotometer

24 Synthesis

241 Synthesis of 2-(4-(4455-Tetramethyl-132-dioxaboro-lane-2-yl)phenyl)-[124]triazolo[34-a]isoquinoline-3(2H)-one (2) In a round-bottom flask compound 1 (56 g163mmol) 4455-tetramethyl-2-(4455-tetramethyl-132-dioxaborolane-2-yl)-132-dioxaborolane (44 g 171mmol)and potassium acetate (48 g 490mmol) were dissolvedin dimethyl sulfoxide (DMSO) under nitrogen atmosphereAfter adding a catalyst of dichloro-[111015840-bis(diphenylphos-phino)ferrocenyl]palladium(II) (Pd(dppf)Cl

2) the mixed

solution was heated at 80∘C for 6 hours with vigorousstirring It was then poured into EtOAc-water for extrac-tion The organic phase was concentrated and adsorbed onsilica gel and purified by column chromatography usinghexaneEtOAc mixture (5 1) as the eluant white powderyield 532 g (842) 1H NMR (300MHz d

6-DMSO) 120575 831

(d 1H 119869 = 753Hz) 817 (d 2H 119869 = 823Hz) 784 (d 3H119869 = 857Hz) 777sim766 (m 3H) 702 (d 1H 119869 = 744Hz) 132(s 12H)

242 Synthesis of 5-(4-(3-Oxo-[124]triazolo[34-a]isoquino-line-2(3H)-yl)phenyl)thiophene-2-carbaldehyde (3) In athree-necked round-bottomed flask (25mL) equippedwith a reflux condenser compound 2 (171 g 44mmol) 5-bromothiophene-2-carbaldehyde (10 g 52mmol) and 2Mpotassium carbonate solution were added to a suspensionof Pd(PPh

3)4

(30mol) in tetrahydrofuran (30mL) atambient temperature under nitrogen The reaction mixturewas heated to 80∘C with rapid stirring for 16 hours Aftercooling the resulting solution was poured into water Theseparated solid was filtered and thoroughly washed withwater-acetone and dried pale yellow powder yield 10 g(616) 1H NMR (300MHz d

6-DMSO) 120575 923 (s 1H) 832

(d 1H 119869 = 756Hz) 824 (d 2H 119869 = 853Hz) 807 (d 1H119869 = 381Hz) 801 (d 2H 119869 = 860Hz) 786sim767 (m 5H)704 (d 1H 119869 = 739Hz)

243 Synthesis of 2-Cyano-3-(5-(4-(3-oxo-[124]triazolo[34-a]isoquinoline-2(3H)-yl)phenyl)thiophene-2-yl)acrylic Acid(4L) In a three-neck bottle compound 3 (12 g 33mmol)2-cyanoacetic acid (06 g 65mmol) and piperidine (008 g098mmol)were dissolved in chloroformThemixed solutionwas refluxed for 16 hours with rapid stirring After coolingthe resulting solution was poured into EtOAc-MeOH Theseparated solid was filtered and thoroughly washed withEtOAc and MeOH and dried pale orange powder yield12 g (850) 1H NMR (300MHz d

6-DMSO) 120575 832 (d 1H

119869 = 750Hz) 823 (s 1H) 820 (d 2H 119869 = 320Hz) 793 (d2H 119869 = 872Hz) 789sim767 (m 6H) 703 (d 1H 119869 = 746Hz)ESI-MS 119898119911 437 (M-H+) Anal Calcd for C

24H14N4O3S C

6574 H 322 N 1278 Found C 6596 H 328 N 1260

3 Results and Discussion

31 Synthesis The synthetic route of the co-adsorbent isshown in Figure 1 2-(4-bromophenyl)-[1 2 4]triazolo[34-a]isoquinoline-3(2H)-one (1)was obtained as reported earlier

International Journal of Photoenergy 3

NN

N

O

Br NN

N

O

B

S CHO

CHO

Br

NN

N

O

S

NN

N

O

SCOOH

CN

1 2

34L

OB

OB

O

O

O

O

piperidineCHCl3

Pd (PPh3)4K2CO3

THF

Pd(dppf)Cl2KOAc DMSO

Figure 1 Synthetic route of co-adsorbent 4L

[16] 4L was synthesized by Suzuki coupling of compound 2with 5-formylthiophene-2-ylboronic acid followed by Kno-evenagel condensation reaction with cyanoacrylic acid in thepresence of piperidine This product was well characterizedby spectroscopic analyses

32 The Double-Layer TiO2Film Recently an enhancement

in light absorption via application of light scattering hasbeen studied for DSSCs [17 18] To take advantage of thelight-scattering effect of TiO

2particles light absorption can

be enhanced in TiO2films by increasing the absorption

path length of photons which can effectively improve thephotocurrent output of cells In order to obtain a highphotoelectric conversion efficiency in DSSCs a double-layerTiO2filmwas fabricated composed of a light-scattering layer

and a transparent layer The transparent layer was preparedby commercial TiO

2paste and the light-scattering layer was

deposited by home-made scattering TiO2paste First TiCl

4

solution was converted to Ti(OH)4gel after ammonia neu-

tralization and H2O2was used to hydrolyze Ti(OH)

4to form

TiO2sol Subsequently the result solutionwas refluxed 35ndash40

hours for crystallization and the anatase type TiO2organic

sol was obtained This solution was concentrated by rotaryevaporator and dispersed in 120572-terpineol with ethyl cellulosefor scattering TiO

2paste After screen-printing the thickness

of the double-layer film was about 16 120583m Figure 2(a) showsthe surfacemorphology of the light-scattering layer revealingtheir well-connected network and the porous nature of TiO

2

film The average sizes of the nanostructures were about100 nm in diameter This results in a good scattering effectbecause of the elongated optical path length Figure 2(b)shows the surface morphology of light-scattering layer afterTiCl4posttreatment From the SEM image one can see that

Table 1 The amount of adsorbed N719 dye for different TiO2structures

TiO2 structureDye adsorption(10minus7 mol cmminus2)

Film 1 FTOtransparent layer 523

Film 2 FTOtransparent layerlight-scatteringlayer 535

Film 3 FTOtransparent layerlight-scatteringlayerTiCl4 posttreatment 702

the necking of the TiO2particles and the surface roughness

are enhanced and resulting in higher dye adsorption amountAs summarized in Table 1 it was found that the dye amounton a film of Film 3-TiCl

4posttreatment is higher than

those of Films 1 and 2 It is well known that the short-circuit current density is mainly determined by the initialnumber of photogenerated electrons and the initial numberof photogenerated electrons could be significantly affected bythe dye amount on the TiO

2filmsThis result agrees well with

recent experiments [19 20] In order to maximize the lightharvesting efficiency we fabricate the structure of Film 3 forthe follow-up discussion of co-adsorbent effect

33 The Concentration Effect of Coadsorbents After opti-mization of the devices the photovoltaic characteristics ofthe small molecule as co-adsorbent for DSSCs were evaluatedwith a sandwich DSSC cell (as shown in Figure 3) using06M [BMI][I] 01M GuNCS 03M I

2 and 05M TBP

in a ANVN (8515 vv) solvent as the redox electrolyteDetails of the device preparation and characterization aredescribed in the experimental section and all the essentialproperties of these cells are listed in Figure 3 and Table 2


(a) (b)

Figure 2 SEM images of (a) light-scattering layer of double layer TiO2films and (b) TiCl

4posttreatment of light-scattering layer

Table 2 Photovoltaic parameters of the DSSCs with N719 4L in different molar ratios under AM 15G sunlighta

Dyestuff coadsorbentmolar ratio 119869sc (mA cmminus2) 119881oc (V) FF 120578 ()

Device A N719 1565 076 070 836

Device B N719-4L1 025 1639 077 070 883

Device C N719-4L1 050 1527 076 071 821

Device D N719-4L1 1 1572 075 069 810

aPerformances of DSSCs were measured with 025 cm2 working area

Under the standard AM 15G irradiation the maximumefficiency (120578) for the N719-sensitized solar cell-device B withan active area of 025 cm2 was calculated to be 836 witha 119869sc of 1565mA cmminus2 a 119881oc of 076V and a fill factor (FF)of 070 However the solar cells based on the 12 + 4 120583mtransparent layer which was sensitized by N719-4L with 1to 025 molar ratio yielded a remarkably high photocurrentdensity of 1639mA cmminus2 an open circuit voltage of 077Vand a fill factor of 070 corresponding to an overall powerconversion efficiency of 883This result is also in agreementwith the observation of the incident photon-to-electronconversion efficiency (IPCE) action spectra of DSSCs pre-sented in Figure 4With the increase in 4L concentration theoverall power conversion efficiency shows a downward trendCompared to device A with a single dyestuff-N719 devicesC and D based on a high 4L molar ratio exhibit lower 120578values of 821 and 810 It is well known that co-adsorbentswill compete with N719 for adsorption on the TiO

2surface

This result shows that N719 and co-adsorbent 4L are inbalance at a 1 to 025 molar ratio In this concentrationof cosensitizers N719 may occupy positions on the TiO

2

surface and coadsorbent 4L then anchors to the blank tocreate a perfect insulating molecular layer Because of thislayer the charge recombination process can be shielded andthe incident photo-to-electron conversion efficiency can beenhanced and this increases 119881oc 119869sc and 120578 On the other

hand devices C and D show downward trend at 119881oc and FFvalues in comparison with device A This indicates that co-adsorbent 4L has considerable superiority at 1 to 050 and1 to 1 molar ratios with some N719 molecules having losttheir positions on TiO

2and being replaced by co-adsorbent

4LThis increases the opportunities for 120587-120587 stacking of smallorganic molecule-4L and decreases the contribution of N719to the incident photon-to-electron conversion efficiency [20ndash22] These photovoltaic performance results indicate thatcoadsorption with 4L and N719 in an appropriate concentra-tion is effective in improving solar cell performance

4 Conclusions

A new triazoloisoquinoline-based co-adsorbent has beenprepared and applied in DSSC This study demonstrates thatcoadsorption of N719 sensitizer with triazoloisoquinoline-based organic small molecule onto nanocrystalline TiO

2

films significantly increases the photovoltage and photocur-rent thus enhancing the total conversion efficiency Afteroptimization of the structure of the TiO

2layer the cell

produced in this work achieved an energy conversion effi-ciency as high as 883 at 100mWcmminus2 and AM 15G at1 to 025 (N719 co-adsorbent) molar ratio This improvedconversion efficiency is attributed to the insulatingmolecularlayer which was composed of small molecule 4L and N719


00 01 02 03 04 05 06 07 080

2

4

6

8

10

12

14

16

18

Photovoltage (V)Device ADevice B

Device CDevice D

Curr

ent d

ensit

y (m

A cm

minus2)

Figure 3 Photocurrent density-voltage characteristics of solarcells sensitized by N719 (Device A) N719 4L (1 025) (Device B)N719 4L (1 05) (Device C) and N719 4L (1 1) (Device D) with120 + 40 120583m double layers nanocrystalline TiO

2electrodes

300 350 400 450 500 550 600 650 700 750 800 8500

10

20

30

40

50

60

70

80

90

IPCE

()

Wavelength (nm)

Device ADevice B

Device CDevice D

Figure 4 IPCE action spectra of solar cells sensitized by N719(Device A) N719 4L (1 025) (Device B) N719 4L (1 05) (DeviceC) and N719 4L (1 1) (Device D) with 120 + 40 120583m double layersnanocrystalline TiO

2electrodes

and the charge recombination process can be shielded Thisbreakthrough will contribute to promoting organic smallmolecule as co-adsorbents in DSSC

References

[1] B OrsquoRegan and M Gratzel ldquoA low-cost high-efficiency solarcell based on dye-sensitized colloidal TiO

2filmsrdquo Nature vol

353 no 6346 pp 737ndash740 1991[2] M Gratzel ldquoConversion of sunlight to electric power by

nanocrystalline dye-sensitized solar cellsrdquo Journal of Photo-chemistry and Photobiology A vol 164 pp 3ndash14 2004

[3] J N de Freitas A F Nogueira and M-A de Paoli ldquoNewinsights into dye-sensitized solar cells with polymer elec-trolytesrdquo Journal of Materials Chemistry vol 19 no 30 pp5279ndash5294 2009

[4] M Gorlov and L Kloo ldquoIonic liquid electrolytes for dye-sensitized solar cellsrdquo Dalton Transactions no 20 pp 2655ndash2666 2008

[5] B Li L Wang B Kang P Wang and Y Qiu ldquoReview of recentprogress in solid-state dye-sensitized solar cellsrdquo Solar EnergyMaterials and Solar Cells vol 90 no 5 pp 549ndash573 2006

[6] M K Nazeeruddin A Kay I Rodicio and M GratzelldquoConversion of light to electricity by cis-X

2bis(221015840-bipyridyl-

441015840-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X= Clminus Brminus Iminus CNminus and SCNminus) on nanocrystalline TiO

2

electrodesrdquo Journal of the American Chemical Society vol 115no 14 pp 6382ndash6390 1993

[7] H Paulsson A Hagfeldt and L Kloo ldquoMolten and solidtrialkylsulfonium iodides and their polyiodides as electrolytesin dye-sensitized nanocrystalline solar cellsrdquo Journal of PhysicalChemistry B vol 107 no 49 pp 13665ndash13670 2003

[8] J-H Yum P Walter S Huber et al ldquoEfficient far red sen-sitization of nanocrystalline TiO

2films by an unsymmetrical

squaraine dyerdquo Journal of the American Chemical Society vol129 no 34 pp 10320ndash10321 2007

[9] H Tian X Yang J Cong et al ldquoTuning of phenoxazinechromophores for efficient organic dye-sensitized solar cellsrdquoChemical Communications no 41 pp 6288ndash6290 2009

[10] S Ito H Miura S Uchida et al ldquoHigh-conversion-efficiencyorganic dye-sensitized solar cells with a novel indoline dyerdquoChemical Communications no 41 pp 5194ndash5196 2008

[11] J-C Chang C-H Yang H-H Yang et al ldquoPyridiniummoltensalts as co-adsorbents in dye-sensitized solar cellsrdquo Solar Energyvol 85 no 1 pp 174ndash179 2011

[12] H Kusama and H Arakawa ldquoInfluence of pyrimidine additivesin electrolytic solution on dye-sensitized solar cellrdquo Journal ofPhotochemistry and Photobiology A vol 160 no 3 pp 171ndash1792003

[13] S Ruhle M Greenshtein S-G Chen et al ldquoMolecular adjust-ment of the electronic properties of nanoporous electrodes indye-sensitized solar cellsrdquo Journal of Physical Chemistry B vol109 no 40 pp 18907ndash18913 2005

[14] M Wang C Gratzel S-J Moon et al ldquoSurface design insolid-state dye sensitized solar cells effects of zwitterionic co-adsorbents on photovoltaic performancerdquoAdvanced FunctionalMaterials vol 19 no 13 pp 2163ndash2172 2009

[15] Y M Lin S L Liu and Y H Tseng ldquoPhotocatalytic titaniumoxide solution and method for producing the samerdquo TWI30690 2005

[16] C Y Chiu C N Kuo W F Kuo and M Y Yeh ldquoStudies on thereaction of 120572-chlororformylarylhydrazine hydrochloride withN-heterocyclic comoundsrdquo Journal of the Chinese ChemicalSociety vol 49 p 239 2002

[17] S Hore C Vetter R Kern H Smit and A Hinsch ldquoInfluenceof scattering layers on efficiency of dye-sensitized solar cellsrdquoSolar Energy Materials and Solar Cells vol 90 no 9 pp 1176ndash1188 2006

[18] S Ito T N Murakami P Comte et al ldquoFabrication of thin filmdye sensitized solar cells with solar to electric power conversionefficiency over 10rdquoThin Solid Films vol 516 no 14 pp 4613ndash4619 2008


[19] P M Sommeling B C OrsquoRegan R R Haswell et al ldquoInfluenceof a TiCl

4post-treatment on nanocrystalline TiO

2films in dye-

sensitized solar cellsrdquo Journal of Physical Chemistry B vol 110no 39 pp 19191ndash19197 2006

[20] M-S Wu C-H Tsai J-J Jow and T-C Wei ldquoEnhanced per-formance of dye-sensitized solar cell via surfacemodification ofmesoporous TiO

2photoanode with electrodeposited thin TiO

2

layerrdquo Electrochimica Acta vol 56 no 24 pp 8906ndash8911 2011[21] X-F Wang H Tamiaki L Wang et al ldquoChlorophyll-a deriva-

tives with various hydrocarbon ester groups for efficient dye-sensitized solar cells static and ultrafast evaluations on electroninjection and charge collection processesrdquo Langmuir vol 26no 9 pp 6320ndash6327 2010

[22] F Gao Y Cheng Q Yu et al ldquoConjugation of selenophene withbipyridine for a high molar extinction coefficient sensitizer indye-sensitized solar cellsrdquo Inorganic Chemistry vol 48 no 6pp 2664ndash2669 2009

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2 Experimental

21 General Procedure for Preparation of Solar CellsFluorine-doped tin oxide (FTO 10Ω squareminus1) glass plateswere cleaned using detergent solution water and ethanol inan ultrasonic bath overnight The screen-printing procedurewas repeated with TiO

2paste (sim15ndash20 nm colloidal particles

Ti-Nanoxide T series Solaronix SA) to obtain a transparentnanocrystalline film of thickness around 12 120583m The 100 nmcolloidal particles were prepared in a basic environmentaccording to the literature [15] and dispersed in 120572-terpineolwith ethyl cellulose for scattering TiO

2paste A scattering

layer around 4 120583m was deposited by using this scatteringTiO2paste and a final thickness of 16120583m was attained

The TiO2electrodes were gradually annealed at 450∘C for

30min in an oven in an air atmosphere After sintering theelectrodes were further treated with 02M TiCl

4aqueous

solution at room temperature for 12 h then washed withwater and ethanol and annealed at 450∘C for 30min Whenthe temperature decreased to 70∘C after sintering theelectrodes were immersed into dye solution which included05mM N719 and different concentrations of co-adsorbentin tert-butanolacetonitrile (AN) (1 1 in volume) The dyesolutions were kept at 25∘C for more than 18 h to allow thedye to adsorb to the TiO

2surface After the adsorption of

the dyes the electrode was rinsed with the same solventThe dye-loaded TiO

2film as the working electrode and

Pt-coated TCO as the counterelectrode (about 20 nm) wereseparated by a hot-melt Surlyn sheet (25120583m) and sealedtogether by pressing them under heat The electrolyteswere introduced into the gap between the working andcounterelectrodes from two holes predrilled on the back ofthe counterelectrode Finally the two holes were sealed witha Surlyn film covering a thin glass slide under heat The cellswere evaluated by using 06M [BMI][I] 01MGuNCS 03MI2 and 05M TBP in a ANVN (8515 vv) solvent as the

redox electrolyte

22 Photovoltaic Measurement The current-voltage (119868-119881)characteristics in the dark and under illumination weremeasured with a Keithley 2400 sourcemeter The photocur-rent was measured in a nitrogen-filled glove box under asolar simulator (Oriel 96000 150W) with AM 15G-filteredillumination (100mWcmminus2)The spectra-mismatch factor ofthe simulated solar irradiation was corrected using a Schottvisible-color glass-filtered (KG5 color filter) Si diode (Hama-matsu S1133) The active area of the device was 025 cm2

23 Dye Loading Measurement The TiO2films were put

into the dye solution (N719 3 times 10minus4M in tert-butanol andacetonitrile 1 1 vv) for 24 h Subsequently the TiO

2films

were washed with acetonitrile after the adsorption processand then dried in N

2flow Dye loading measurements were

conducted by desorbing the dye molecules from the dye-anchored films in NaOH ethanolic solution The loadingamountwas calculated from the absorbance of the completelydesorbed dye solutions by the spectrophotometer

24 Synthesis

241 Synthesis of 2-(4-(4455-Tetramethyl-132-dioxaboro-lane-2-yl)phenyl)-[124]triazolo[34-a]isoquinoline-3(2H)-one (2) In a round-bottom flask compound 1 (56 g163mmol) 4455-tetramethyl-2-(4455-tetramethyl-132-dioxaborolane-2-yl)-132-dioxaborolane (44 g 171mmol)and potassium acetate (48 g 490mmol) were dissolvedin dimethyl sulfoxide (DMSO) under nitrogen atmosphereAfter adding a catalyst of dichloro-[111015840-bis(diphenylphos-phino)ferrocenyl]palladium(II) (Pd(dppf)Cl

2) the mixed

solution was heated at 80∘C for 6 hours with vigorousstirring It was then poured into EtOAc-water for extrac-tion The organic phase was concentrated and adsorbed onsilica gel and purified by column chromatography usinghexaneEtOAc mixture (5 1) as the eluant white powderyield 532 g (842) 1H NMR (300MHz d

6-DMSO) 120575 831

(d 1H 119869 = 753Hz) 817 (d 2H 119869 = 823Hz) 784 (d 3H119869 = 857Hz) 777sim766 (m 3H) 702 (d 1H 119869 = 744Hz) 132(s 12H)

242 Synthesis of 5-(4-(3-Oxo-[124]triazolo[34-a]isoquino-line-2(3H)-yl)phenyl)thiophene-2-carbaldehyde (3) In athree-necked round-bottomed flask (25mL) equippedwith a reflux condenser compound 2 (171 g 44mmol) 5-bromothiophene-2-carbaldehyde (10 g 52mmol) and 2Mpotassium carbonate solution were added to a suspensionof Pd(PPh

3)4

(30mol) in tetrahydrofuran (30mL) atambient temperature under nitrogen The reaction mixturewas heated to 80∘C with rapid stirring for 16 hours Aftercooling the resulting solution was poured into water Theseparated solid was filtered and thoroughly washed withwater-acetone and dried pale yellow powder yield 10 g(616) 1H NMR (300MHz d

6-DMSO) 120575 923 (s 1H) 832

(d 1H 119869 = 756Hz) 824 (d 2H 119869 = 853Hz) 807 (d 1H119869 = 381Hz) 801 (d 2H 119869 = 860Hz) 786sim767 (m 5H)704 (d 1H 119869 = 739Hz)

243 Synthesis of 2-Cyano-3-(5-(4-(3-oxo-[124]triazolo[34-a]isoquinoline-2(3H)-yl)phenyl)thiophene-2-yl)acrylic Acid(4L) In a three-neck bottle compound 3 (12 g 33mmol)2-cyanoacetic acid (06 g 65mmol) and piperidine (008 g098mmol)were dissolved in chloroformThemixed solutionwas refluxed for 16 hours with rapid stirring After coolingthe resulting solution was poured into EtOAc-MeOH Theseparated solid was filtered and thoroughly washed withEtOAc and MeOH and dried pale orange powder yield12 g (850) 1H NMR (300MHz d

6-DMSO) 120575 832 (d 1H

119869 = 750Hz) 823 (s 1H) 820 (d 2H 119869 = 320Hz) 793 (d2H 119869 = 872Hz) 789sim767 (m 6H) 703 (d 1H 119869 = 746Hz)ESI-MS 119898119911 437 (M-H+) Anal Calcd for C

24H14N4O3S C

6574 H 322 N 1278 Found C 6596 H 328 N 1260

3 Results and Discussion

31 Synthesis The synthetic route of the co-adsorbent isshown in Figure 1 2-(4-bromophenyl)-[1 2 4]triazolo[34-a]isoquinoline-3(2H)-one (1)was obtained as reported earlier


NN

N

O

Br NN

N

O

B

S CHO

CHO

Br

NN

N

O

S

NN

N

O

SCOOH

CN

1 2

34L

OB

OB

O

O

O

O

piperidineCHCl3

Pd (PPh3)4K2CO3

THF












4



4to form






2














2 and 05M TBP



(a) (b)





Device A N719 1565 076 070 836

Device B N719-4L1 025 1639 077 070 883

Device C N719-4L1 050 1527 076 071 821

Device D N719-4L1 1 1572 075 069 810



2surface


2





4 Conclusions


2


2layer the cell



00 01 02 03 04 05 06 07 080

2

4

6

8

10

12

14

16

18


Device CDevice D

Curr

ent d

ensit

y (m

A cm

minus2)


2electrodes

300 350 400 450 500 550 600 650 700 750 800 8500

10

20

30

40

50

60

70

80

90

IPCE

()

Wavelength (nm)

Device ADevice B

Device CDevice D


2electrodes


References











2



















2films in dye-




2













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


NN

N

O

Br NN

N

O

B

S CHO

CHO

Br

NN

N

O

S

NN

N

O

SCOOH

CN

1 2

34L

OB

OB

O

O

O

O

piperidineCHCl3

Pd (PPh3)4K2CO3

THF












4



4to form






2














2 and 05M TBP



(a) (b)





Device A N719 1565 076 070 836

Device B N719-4L1 025 1639 077 070 883

Device C N719-4L1 050 1527 076 071 821

Device D N719-4L1 1 1572 075 069 810



2surface


2





4 Conclusions


2


2layer the cell



00 01 02 03 04 05 06 07 080

2

4

6

8

10

12

14

16

18


Device CDevice D

Curr

ent d

ensit

y (m

A cm

minus2)


2electrodes

300 350 400 450 500 550 600 650 700 750 800 8500

10

20

30

40

50

60

70

80

90

IPCE

()

Wavelength (nm)

Device ADevice B

Device CDevice D


2electrodes


References











2



















2films in dye-




2













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


(a) (b)





Device A N719 1565 076 070 836

Device B N719-4L1 025 1639 077 070 883

Device C N719-4L1 050 1527 076 071 821

Device D N719-4L1 1 1572 075 069 810



2surface


2





4 Conclusions


2


2layer the cell



00 01 02 03 04 05 06 07 080

2

4

6

8

10

12

14

16

18


Device CDevice D

Curr

ent d

ensit

y (m

A cm

minus2)


2electrodes

300 350 400 450 500 550 600 650 700 750 800 8500

10

20

30

40

50

60

70

80

90

IPCE

()

Wavelength (nm)

Device ADevice B

Device CDevice D


2electrodes


References











2



















2films in dye-




2













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00 01 02 03 04 05 06 07 080

2

4

6

8

10

12

14

16

18


Device CDevice D

Curr

ent d

ensit

y (m

A cm

minus2)


2electrodes

300 350 400 450 500 550 600 650 700 750 800 8500

10

20

30

40

50

60

70

80

90

IPCE

()

Wavelength (nm)

Device ADevice B

Device CDevice D


2electrodes


References











2



















2films in dye-




2













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




2films in dye-




2













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

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