ruangchai tarsang e-mail: [email protected] department of chemistry, faculty of science,...
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Ruangchai Tarsang
E-mail: [email protected]
Department of Chemistry, Faculty of Science, Ubon Ratchathani UniversityCenter for Organic Electronics and Alternative Energy
Pure and Applied Chemistry International Conference (PACCON2013)
January 24th, 2013
The Tide Resort, Bangsaen Beach, Chon Buri, Thailand
Tuning the electron donating ability in the triphenylamine-based D--A dye with enhanced power conversion
efficiency of dye-sensitized solar cells
Conclusions5
Objectives2
Computational Details3
Results and Discussion4
Outline of Presentation
Background and Significance 1
2
1.Background and Significance
Dye-sensitized solar cells (DSSCs)Dye-sensitized solar cells (DSSCs)
Prof. M. Grätzel, Switzerland, 1991
Advantages : low cost materials easy to be fabricated friendly to the enviroment still very low power conversion efficiency
DSSCs
expensive raw material complicate fabrication process toxic gases
Disadvantages :
Silicon solar cell
3
Basic Working principle of DSSCsBasic Working principle of DSSCs
e-
e-
DSSCs components: Sensitizer (Dye) Metal Oxide layer Electrolyte system Electrodes
- Working electrode - Counter electrode
1.Background and Significance
4
e-
e-
1.Background and Significance
Classification of DSSCsClassification of DSSCs
Suitable sensitizer : for increasing DSSCs efficiency
1) Ruthenium complexes:
2) Organic-based dyes: coumarins porphyrin indoline
~ 11%
~ 5-9%Adv. Mater. 2006, 18, 1202-1205
N N
S
OHOOC
N
S
O
D149 = 9 %
Coord Chem Rev . 2004, 248, 1363-1379;
N
N
COOH
Ru
N
N
HOOC
HOOC
COOH
NCSNCS
N3 Dye
N
N
COOH
Ru
N
N
TBAOOC
HOOC
COOABT
NCSNCS
N719 = 10% = 11.4 %
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rare material complicate synthesis
Disadvantages :
3. Suitable energy levels
2. One direction of electron flow
1. Wide absocccrption range
Criteria for efficient DSSCsCriteria for efficient DSSCs
1.Background and Significance
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H. Tian et al, Chem. Commun., 2007, 3741 - 374
HOMO LUMO
1.Background and Significance
Triphenylamine (TPA) dyes in DSSCsTriphenylamine (TPA) dyes in DSSCs
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NS
CN
COOHD--
HOMO
LUMO
Chem. Commun., 2006, 2245–2247
an efficient intramolecular charge separation
1.Background and Significance
Triphenylamine (TPA) dyes in DSSCsTriphenylamine (TPA) dyes in DSSCs
8
NS
CN
COOHD--
J. Org. Chem., 2008, 73, 3791–3797
D-D--A Developed: modifying the molecular structure, especially the electron donor
block the charge recombination reduce the intermolecular π–π stacking
Eur. J. Org. Chem., 2012
Recently
2.Objectives
Organic materials for application in DSSCsOrganic materials for application in DSSCs
NS
CN
COOH
Donor
NS
CN
COOH
NS
CN
COOHD--
2D-D--
D-D--
Donor
Donor
Donor =
N
TPA1
N
N
TPA2
N
N
N
N
N
TPA3
• To study the effect of the substituted donating group number
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carbazole
2.Objectives
Organic materials for application in DSSCsOrganic materials for application in DSSCs
10
Donor =
N
N
N
N
N
TPA4
TPA5
NS
CN
COOH
Donor
NS
CN
COOH
NS
CN
COOHD--
2D-D--
D-D--
Donor
Donor
• To study the effect of the different substituted donating group
diphenylamine
3.Computational Details
Structural and energetic calculations of DSSCsStructural and energetic calculations of DSSCs
The ground-state geometries DFT with B3LYP/6-31G(d,p)
The excitation energy TD-DFT/CAM-B3LYP//B3LYP/6-31G(d,p)
Absorption spectraSWizard program
All the calculations were performed using the Gaussian 09 program package
• UBUchem server
• Kankrao server
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4.Results and Discussion
Optimal ground-state electronic structuresOptimal ground-state electronic structures
Fig.1 Molecular (a) and Optimized (b) structures of the triphenylamine dyes
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dihedral angle
Dye
Dihedral angle (degree)
D(2D)-D D-π π-ATPA donor
1 - 2 1 - 3TPA -20.76 0.93 46.80 45.62
TPA1 52.88 -21.59 1.00 44.43 47.06
TPA2 53.07 (-52.09)
-22.13 0.63 45.65 45.40
TPA3 36.97(-36.34)
-21.28 0.69 46.52 43.93
TPA4 38.64 -20.64 0.97 49.51 45.03
TPA5 38.80(-39.18)
-19.91 0.99 48.55 47.94
4.Results and Discussion
Optimal ground-state electronic structuresOptimal ground-state electronic structures
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Table 1: Selected dihedral (in degree) of the triphenylamine dyes TPA-TPA5
Fig.1 Molecular (a) and Optimized (b) structures of the triphenylamine dyes
nonplanar conformation
Frontier molecular orbitalsFrontier molecular orbitals
4.Results and Discussion
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HOMO
LUMO
Fig.2 Molecular orbiyals surface of HOMO and LUMO orbitals of the triphenylamine dyes
Increase the electron density for HOMO
Tuning the electron donating ability
Effect of intramolecular charge transfer (ICT)Effect of intramolecular charge transfer (ICT)
4.Results and Discussion
15Fig.3 The density difference between the ground-state and the first excited-state of TPA, TPA1, and TPA2 dyes
CT character of the first transition
density difference map:
(TDDFT/CAM-B3LYP/6-31G(d,p)/CPCM)
Presence the electron transfer going from GS to ES
satisfied
Absorption spectra and Electronic transitionsAbsorption spectra and Electronic transitions
4.Results and Discussion
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N
N
N
N
N
N
TPA
TPA2
TPA1
Fig.4 Simulated absorption spectra of the triphe-nylamine dyes TPA-TPA5 at the CAM-B3LYP/6-31g(d,p) level in dichloromethane solution
TPA
TPA1TPA2
No shifted of abs
Carbazole donor
How can we change the abs of carbazole substituted group?
430
Absorption spectra and Electronic transitionsAbsorption spectra and Electronic transitions
4.Results and Discussion
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N
N
N
N
N
N
N
N
N
N
N
N
N
TPA1
TPA2
TPA3
TPA4
TPA5
Fig.4 Simulated absorption spectra of the triphe-nylamine dyes TPA-TPA5 at the CAM-B3LYP/6-31g(d,p) level in dichloromethane solution
Red-shifted
satisfied
435
441 453
Absorption spectra and Electronic transitionsAbsorption spectra and Electronic transitions
4.Results and Discussion
Table 2. Absorption wavelength (abs), excitation energy (Eg), oscillator strength () and electronic transition configurations of triphenylamine dyes
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Dyeabs /nm, Eg /eV(x10-4 M-1cm-1)
Configuration
TPA 430, 2.88(10.37)
1.4305 HL (80%); H-1L (14%)
TPA1 429, 2.89(10.77)
1.4860 HL (61%); H-1L (21%)
TPA2 428, 2.90(11.16)
1.5399 HL (59%); H-2L (25%)
TPA3 435, 2.85(12.27)
1.6931 HL (61%); H-2L (14%)
TPA4 441, 2.81(10.47)
1.4444 HL (60%); H-1L (25%)
TPA5 453, 2.74(10.58)
1.4596 HL (65%); H-2L (24%)
CT absorption band
Red-shifted
Energy level (eV)
4.Results and Discussion
Molecular orbitals Energy level Molecular orbitals Energy level
Fig. 5. Energy diagram of HOMO and LUMO for the triphenylamine dyes, TiO2, and the electrolyte
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injection from the dye excited statesatisfied
Change the HOMO energy
5.Conclusions
• We have analyzed effect of two different auxiliary donor groups of carbazole and diphenylamine on the ground-state structure, electronic structure as well as the absorption spectra of D-π-A organic dyes.
• Carbazole auxiliary donor provided the large dihedral angle between auxiliary donor and TPA donor resulting in not red-shifted of absorption wavelength.
• This trouble was improved by either introduction fluorine unit between carbazole and TPA groups or replaced carbazole auxiliary donor by diphenylamine group.
• We may conclude that TPA5 dye molecule which is the most red-shifted of absorption spectra have the potential to be employed in the DSSCs applications.
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Department of Chemistry, Faculty of Science,
Ubon Ratchathani University
National Nanotechnology Center:
Center for Organic Electronics and Alternative Energy,
Advisor: Asst.Prof.Dr. Siriporn Jungsuttiwong
Pure and Applied Chemistry International Conference (PACCON2013)
Financial supported:
Human Resource Development in Science Project (Science Achievement Scholarship of Thailand, SAST)
Acknowledgement
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