- Email: [email protected]
Density functional theory study of indigo and its derivatives as photosensitizers for dye-sensitized solar cells
Accepted Manuscript Title: Density Functional Theory Study of Indigo and its Derivatives as Photosensitizers for Dye-Sensitized Solar Cells Authors: Francisco Cervantes-Navarro, Daniel Glossman-Mitnik PII: DOI: Reference:
S1010-6030(13)00036-1 doi:10.1016/j.jphotochem.2013.01.011 JPC 9353
To appear in:
Journal of Photochemistry and Photobiology A: Chemistry
Received date: Revised date: Accepted date:
27-11-2012 10-1-2013 10-1-2013
Please cite this article as: F. Cervantes-Navarro, D. Glossman-Mitnik, Density Functional Theory Study of Indigo and its Derivatives as Photosensitizers for DyeSensitized Solar Cells, Journal of Photochemistry and Photobiology A: Chemistry (2010), doi:10.1016/j.jphotochem.2013.01.011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Density Functional Theory Study of Indigo and its Derivatives as Photosensitizers for Dye-Sensitized Solar Cells
ip t
Francisco Cervantes-Navarro and Daniel Glossman-Mitnik*
cr
NANOCOSMOS Virtual Lab, Centro de Investigación en Materiales Avanzados,
Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih.
*
Author
to
whom
correspondence
an
us
31109, México
should
be
addressed;
E-mail:
M
[email protected], Tel.: +52 614 4391151, Fax: +52 614
Ac ce p
te
d
4394884
Page 1 of 13
Abstract
Theoretical analysss of the indigo dye molecule and its derivatives with Chlorine (Cl), Sulfur (S), Selenium (Se) and Bromine (Br) substituents, were performed using the
ip t
Gaussian 09 software package. Calculations were performed based on the framework of density functional theory (DFT) with the Becke 3-parameter-Lee-Yang-Parr (B3LYP)
cr
functional, where the 6-31G(d,p) basis set was employed. All this for study they properties for be used with metal oxides in dye-sensitized solar cells (DSSC). Each of
us
the molecules was theoretically analyzed. According to this results all dyes can work for DSSC with TiO2, while no one can work with ZnO, and just Indigo can work with
M
an
(ZnO)12.
Ac ce p
te
d
Keywords: Indigo; dye-sensitized solar cells; DSSC; DFT.
Page 2 of 13
Introduction Solar cells are one answer to the global challenge for searching and developing of renewable energy sources, photovoltaic technologies become are scientific topic of interest in the systems of solar to electrical energy conversion cell; for this work we
ip t
contemplate dye sensitized solar cell (DSSC), in this particular we evaluate dye properties with TiO2, ZnO and a (ZnO)12 cluster.
cr
In this study, the Indigo molecule was employed as the base molecule; an important property of Indigo dye is that the position of its lowest absorption band, which gives
us
indigo its color, varies strongly with its environment. Thus, the color of this molecule ranges from red (540 nm, 2.30 eV) in the gas phase, to violet (588 nm. 2.1 1 eV) in a
an
nonpolar solvent, and to blue in polar solvents, such as ethanol (606 nm, 2.05 eV), or in the solid state [1].
M
Precisely, absorption band, in the visible spectrum, was the principal reason why we selected these systems, moreover planarity and durability were properties that we consider useful to DSSC.
d
Almost all of the molecules studied here are industrial dyes. As such, we consider it
te
important to understand the similarities between their properties and hope can be used for DSSC. Research on the crystallographic properties, vibrational spectra,
Ac ce p
chromatographic analyses, and ionization and orbital energies of these dyes has been previously reported. The dyes include the following: Indigo [2-6], Thioindigo [3-5, 8], Selenoindigo [5-7], 6,6'-dichloroindigo [6-7] and 4,4’,6,6'-tetrabromoindigo [9].
Computational Details
GAUSSVIEW 09 software was used to generate the molecular structures, and calculations were performed using GAUSSIAN 09W [10]. Density functional theory (DFT) was implemented for the frequency and energy optimization. Time-dependent DFT (TD-DFT) was employed for the theoretical study of vertical excitation energies. For all the study was employed the same level of theory, the 6-31G(d,p) basis set and the Becke 3-parameter-Lee-Yang-Parr (B3LYP) functional were employed, according to the work of Perpète and Jacquemin (2009)[11]; the basis set was using because we
Page 3 of 13
calculate the molecule of indigo in gas phase with both basis set 6-31G(d,p), 6311G(2d,p) and LanL2DZ, the transition from the first one is the most similar to experimental value 540 nm [12] (536.2 nm with 6-31G(d,p), 550.4 nm with 6-
ip t
311G(2d,p) and 555 nm with LanL2DZ).
Figure 1.
M
an
us
cr
Optimized structure of all molecules included chemical symbol and label of Atoms.
Ac ce p
te
d
A) Indigo
B) Thioindigo
C) Selenoindigo
Page 4 of 13
ip t
M
an
us
cr
D) Dichloroindigo
te
Results and Discussion
d
E) Tetrabromoindigo
The ground state structures for all molecules were with B3LYP/6-31G(d,p) level. The
Ac ce p
discussion about geometrical parameters of the ground state structures is neglected; all molecules have not imaginary frequencies. The dipole moments for all molecules are equal to cero. The highest occupied molecular orbital energies (EHOMO) and the lowest unoccupied molecular orbital energies (ELUMO) of all dyes computed at the B3LYP/6-31G(d,p) level in vacuum are listed in Table 1. Figure 1 shows the optimized structure of the studied molecules. The data of HOMO, LUMO energies was extracted from optimization output. The figure 2 show the levels HOMO-LUMO of the all dyes, included some metal oxides and reduction potential energy of the I-/I3- electrolyte. The TD-DFT output data’s were processed using the SWizard software program [13], and the data were then plotted and compared in a spreadsheet. Included the assignments of the transitions observed in the calculations.
Page 5 of 13
Table 1. The highest occupied molecular orbital energies (EHOMO), the lowest unoccupied
Indigo
-2.77
-5.27
Thioindigo
-3.05
-5.86
Selenoindigo
-3.02
-5.69
Dichloroindigo
-3.08
-5.63
Tetrabromoindigo
-3.26
-6.79
cr
ELUMO
us
EHOMO
an
Dye
ip t
molecular orbital energies (ELUMO).
M
Energies in eV.
When the frontier molecular orbital of all dyes is compared with the corresponding to metal oxides TiO2, ZnO and (ZnO)12 cluster, we can see easily in figure 2, which one can
d
work like photosensitizers, for each metal oxide. In this case no one is adapting to ZnO
te
bulk, but for (ZnO)12 cluster, the indigo can work, and maybe increase charge injection efficiency (CIE) owing to the closely LUMO level. For TiO2 Tetrabromoindigo dye may
Ac ce p
work better, for CIE, even the difference HOMO donator LUMO acceptor help to avoid electron recombination. The other dye can work properly with TiO2, over all take in count the proximity HOMO level, but more negative, to reduction potential energy of the I−/I3− electrolyte.
Page 6 of 13
Figure 2. Schematic energies HOMO and LUMO diagram of dyes, Zinc Oxide, Titanium dioxide
-3.08
-6.83
Dichloroindigo
-5.69
-5.63
I-/I3-4.80
-6.79
Energies in eV.
b c
Theoretical data from Ref [14]
Ac ce p
a
te
d
-7.16
M
-5.86
Tetrabromoindigo
-5.78
us
-5.27
an
-4.04
-3.26
cr
-3.02
b
Indigo
TiO2
-3.05
Selenoindigo
(ZnO)12c -2.77 -2.79
-2.03
Thioindigo
ZnOa
ip t
and (ZnO)12 cluster, and electrolyte (I−/I3−).
Experimental data from [15]
Theoretical data from Ref [16].
One important factor, efficiency DSSC related, is the efficiency of the dye in response to the incident light. The light harvesting efficiency (LHE) of the dye was evaluated. This value most be the higher as possible to maximize the photocurrent response [17]. (1) Where A and ƒ are the absorption and oscillating strength, respectably, corresponding to absorption energy of the dye. TD-DFT underestimates the transition probabilities.
Page 7 of 13
The LHE was underweighted for this calculation. The values calculated for LHE has been showed in Table 2. In Table 2 are showed every vertical excited singlet states, transition energies and oscillating strength of all dyes. Each molecule show HOMO-LUMO transitions in λmax,
ip t
but just Indigo and Tetrabromoindigo show higher oscillating strength in this
transition. The first vertical excitation energies (ΔEexcit), corresponding to HOMO-LUMO
cr
transition, is showing, even the only other transition, which for Thioindigo,
us
Selenoindigo and Dichloroindigo had the higher oscillating strength.
Table 2.
an
The vertical singlet states, transition character, oscillating strength of the absorption bands in UV–vis region for all dyes; plus light harvesting efficiency (LHE).
Thioindigo
Energiesb
536.2 321.2
Transition characterc
LHE
2.31
0.2673
H-0→L+0(+70%)
0.460
3.86
0.2291
H-3→L+0(+85%)
0.410
2.43
0.1964
H-0→L+0(+98%)
0.364
3.85
0.202
H-3→L+0(+93%)
0.372
547.4
2.26
0.1697
H-0→L+0(+99%)
0.323
323.4
3.83
0.1897
H-4→L+0(+94%)
0.354
525.4
2.36
0.2973
H-0→L+0(+100%)
0.496
345.3
3.59
0.3578
H-3→L+0(+96%)
0.561
533.4
2.32
0.3934
H-0→L+0(+100%)
0.596
363.6
3.41
0.2215
H-2→L+0(+97%)
0.400
510.7
M
ƒ
d
Indigo
λa
te
Dye
Ac ce p
321.8 Selenoindigo
Dichloroindigo
Tetrabromoindigo a
In nm.
b
In eV.
c
Major contribution to the transitions are in parenthesis.
Page 8 of 13
According to LHE, Tetrabromoindigo is the most efficient, follow for Dichoroindigo and Indigo. From this, we can assume that substitutes of H can increase the properties of Indigo derivates dyes for their use in DSSC. This can be subject for other work. Conclusions
ip t
Each of the molecules was theoretically analyzed. According to thermodynamic, the spontaneous charge transfer process from the dye in excited state to the conduction
cr
band of metal oxide, need that the LUMO energy of the dye be more positive potential than conductive band energy of the metal oxide, while the HOMO energy of the dye
us
most be more negative than reduction potential energy of the I−/I3− electrolyte. The calculations show that all dyes can work for DSSC with TiO2, because all have LUMOS
an
less negative than TiO2 LUMO, while no one have less negative HOMO than the redox potential energy of electrolyte; no one can work with ZnO, and just Indigo can work with (ZnO)12, Tetrabromoindigo have the higher LHE of this dyes, which one we
Acknowledgements
d
M
recommended for DSCC with TiO2; we expect that these dyes will be tested for DSSC.
te
This work has been partially supported by Consejo Nacional de Ciencia y Tecnología
Ac ce p
(CONACYT, Mexico). FCN gratefully acknowledges a fellowship from CONACYT. DGM is a researcher with CONACYT and CIMAV.
References [1]
L. Serrano-Andrés, B. O. Roos, A Theoretical Study of the Indigoid Dyes and
Their Chromophore, Chemistry – A European Journal 3 (1997) 717–725. [2]
P. Süsse, M. Steins, V. Kupcik, Indigo: Crystal structure refinement based on
synchrotron data, Zeitshrift fü Kristallographie 184 (1988) 269–273. [3]
J. Tomkinson, M. Bacci, M. Picollo, D. Colognesi, The vibrational spectroscopy of
indigo: A reassessment, Vibrational Spectroscopy 50 (2009) 268-276. [4]
Z. C. Koren, High-performance liquid chromatographic analysis of an ancient
Tyrian Purple dyeing vat from Israel, Israel Journal of Chemistry 35 (1995) 117-124.
Page 9 of 13
[5]
H. Bauer, K. Kowski, H. Kuhn, W. Lüttke, P. Rademacher, Photoelectron spectra
and electronic structures of some indigo dyes, Journal of Molecular Structure 445 (1998) 277-286. [6]
T. Karapanayiotis, S. E. Jorge-Villar, R. D. Bowen, H. G. M. Edwards, Raman
ip t
spectroscopic and structural studies of indigo and its four 6,6′-dihalogeno analogues, Analyst 129 (2004) 613–618.
P. Süsse, G. Kunz, W. Lüttke, Zur Kristallstruktur des Selenoindigos,
cr
[7]
Naturwissenschaften 60 (1973) 49-50.
W. Haase-Wessel, M. Ohmasa, P. Süsse, Thioindigo: Crystal structural data for
modification II, Naturwissenschaften 64 (1977) 435.
M. I. G. M. G. Travasso, P. C. Santos, A. M. F. Oliveira-Campos, Indigo revisited,
an
[9]
us
[8]
Advances in Colour Science and technology 6 (2003) 95-99.
M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R.
M
[10]
Cheeseman, J.A. Montgomery, Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S.
d
Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Ukuda, J. Hasegawa, M.
te
Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox, H.P.
Ac ce p
Hratchian, J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M. C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Anayakkara, M. Challacombe, P.M. W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A. Pople: Gaussian 03, Revision B.05, Pople, Gaussian, Inc., Pittsburgh PA, 2003. [11]
E. A. Perpète, D. Jacquemin, TD-DFT benchmark for indigoïd dyes, Journal of
Molecular Structure: THEOCHEM 914 (2009) 100-105. [12]
J. Tomkinson, M. Bacci, M. Picollo, D. Colognesi, The vibrational spectroscopy of
indigo: A reassessment, Vibrational Spectroscopy 50 (2009) 268–276.
Page 10 of 13
[13]
S.I. Gorelsky, SWizard program 2011. University of Ottawa, Ottawa, Canada,
Available from http://www.sg-chem.net/. [14]
S. Nénon, R. Méreau, S. Salman, F. Castet, Van Regemorter T., Clima S.,
Beljonne D., Cornil J., Structural and Electronic Properties of the TTF/ZnO(10–10)
ip t
Interface: Insights From Modeling, The Journal of Physical Chemistry Letters 3 (2012) 58-63.
J. B. Asbury, Y. Q. Wang, E. Hao, H. N. Ghosh, T. Lian, Evidences of hot excited
cr
[15]
state electron injection from sensitizer molecules to TiO2 nanocrystalline thin films,
[16]
us
Research on Chemical Intermediates 27 (2001) 393-406.
M. A. Flores-Hidalgo, D. Barraza-Jimenez, D. Glosmman-Mitnik, Effects of sulfur
an
substitutional impurities on (ZnO)n clusters (n = 4–12) using density functional theory, Computational and Theoretical Chemistry 965 (2011) 154-162. H. S. Nalwa, Handbook of Advanced Electronic and Photonic Materials and
Ac ce p
te
d
Devices; Academic: San Diego, 2001.
M
[17]
Page 11 of 13
Graphical Abstract (for review)
us
cr
A) Indigo
ip t
Optimized structure of all molecules included chemical symbol and label of Atoms.
C) Selenoindigo
Ac ce p
te
d
M
an
B) Thioindigo
D) Dichloroindigo
E) Tetrabromoindigo
Page 12 of 13
Highlights Each of the molecules was theoretically analyzed as potential photosensitizers
ip t
for DSSC. The calculations show that all dyes can work for DSSC with TiO2 and no one can
cr
work with ZnO.
us
No one have less negative HOMO than the redox potential energy of electrolyte.
Ac ce p
te
d
M
an
We expect that these dyes will be tested for DSSC.
Page 13 of 13
S1010-6030(13)00036-1 doi:10.1016/j.jphotochem.2013.01.011 JPC 9353
To appear in:
Journal of Photochemistry and Photobiology A: Chemistry
Received date: Revised date: Accepted date:
27-11-2012 10-1-2013 10-1-2013
Please cite this article as: F. Cervantes-Navarro, D. Glossman-Mitnik, Density Functional Theory Study of Indigo and its Derivatives as Photosensitizers for DyeSensitized Solar Cells, Journal of Photochemistry and Photobiology A: Chemistry (2010), doi:10.1016/j.jphotochem.2013.01.011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Density Functional Theory Study of Indigo and its Derivatives as Photosensitizers for Dye-Sensitized Solar Cells
ip t
Francisco Cervantes-Navarro and Daniel Glossman-Mitnik*
cr
NANOCOSMOS Virtual Lab, Centro de Investigación en Materiales Avanzados,
Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih.
*
Author
to
whom
correspondence
an
us
31109, México
should
be
addressed;
E-mail:
M
[email protected], Tel.: +52 614 4391151, Fax: +52 614
Ac ce p
te
d
4394884
Page 1 of 13
Abstract
Theoretical analysss of the indigo dye molecule and its derivatives with Chlorine (Cl), Sulfur (S), Selenium (Se) and Bromine (Br) substituents, were performed using the
ip t
Gaussian 09 software package. Calculations were performed based on the framework of density functional theory (DFT) with the Becke 3-parameter-Lee-Yang-Parr (B3LYP)
cr
functional, where the 6-31G(d,p) basis set was employed. All this for study they properties for be used with metal oxides in dye-sensitized solar cells (DSSC). Each of
us
the molecules was theoretically analyzed. According to this results all dyes can work for DSSC with TiO2, while no one can work with ZnO, and just Indigo can work with
M
an
(ZnO)12.
Ac ce p
te
d
Keywords: Indigo; dye-sensitized solar cells; DSSC; DFT.
Page 2 of 13
Introduction Solar cells are one answer to the global challenge for searching and developing of renewable energy sources, photovoltaic technologies become are scientific topic of interest in the systems of solar to electrical energy conversion cell; for this work we
ip t
contemplate dye sensitized solar cell (DSSC), in this particular we evaluate dye properties with TiO2, ZnO and a (ZnO)12 cluster.
cr
In this study, the Indigo molecule was employed as the base molecule; an important property of Indigo dye is that the position of its lowest absorption band, which gives
us
indigo its color, varies strongly with its environment. Thus, the color of this molecule ranges from red (540 nm, 2.30 eV) in the gas phase, to violet (588 nm. 2.1 1 eV) in a
an
nonpolar solvent, and to blue in polar solvents, such as ethanol (606 nm, 2.05 eV), or in the solid state [1].
M
Precisely, absorption band, in the visible spectrum, was the principal reason why we selected these systems, moreover planarity and durability were properties that we consider useful to DSSC.
d
Almost all of the molecules studied here are industrial dyes. As such, we consider it
te
important to understand the similarities between their properties and hope can be used for DSSC. Research on the crystallographic properties, vibrational spectra,
Ac ce p
chromatographic analyses, and ionization and orbital energies of these dyes has been previously reported. The dyes include the following: Indigo [2-6], Thioindigo [3-5, 8], Selenoindigo [5-7], 6,6'-dichloroindigo [6-7] and 4,4’,6,6'-tetrabromoindigo [9].
Computational Details
GAUSSVIEW 09 software was used to generate the molecular structures, and calculations were performed using GAUSSIAN 09W [10]. Density functional theory (DFT) was implemented for the frequency and energy optimization. Time-dependent DFT (TD-DFT) was employed for the theoretical study of vertical excitation energies. For all the study was employed the same level of theory, the 6-31G(d,p) basis set and the Becke 3-parameter-Lee-Yang-Parr (B3LYP) functional were employed, according to the work of Perpète and Jacquemin (2009)[11]; the basis set was using because we
Page 3 of 13
calculate the molecule of indigo in gas phase with both basis set 6-31G(d,p), 6311G(2d,p) and LanL2DZ, the transition from the first one is the most similar to experimental value 540 nm [12] (536.2 nm with 6-31G(d,p), 550.4 nm with 6-
ip t
311G(2d,p) and 555 nm with LanL2DZ).
Figure 1.
M
an
us
cr
Optimized structure of all molecules included chemical symbol and label of Atoms.
Ac ce p
te
d
A) Indigo
B) Thioindigo
C) Selenoindigo
Page 4 of 13
ip t
M
an
us
cr
D) Dichloroindigo
te
Results and Discussion
d
E) Tetrabromoindigo
The ground state structures for all molecules were with B3LYP/6-31G(d,p) level. The
Ac ce p
discussion about geometrical parameters of the ground state structures is neglected; all molecules have not imaginary frequencies. The dipole moments for all molecules are equal to cero. The highest occupied molecular orbital energies (EHOMO) and the lowest unoccupied molecular orbital energies (ELUMO) of all dyes computed at the B3LYP/6-31G(d,p) level in vacuum are listed in Table 1. Figure 1 shows the optimized structure of the studied molecules. The data of HOMO, LUMO energies was extracted from optimization output. The figure 2 show the levels HOMO-LUMO of the all dyes, included some metal oxides and reduction potential energy of the I-/I3- electrolyte. The TD-DFT output data’s were processed using the SWizard software program [13], and the data were then plotted and compared in a spreadsheet. Included the assignments of the transitions observed in the calculations.
Page 5 of 13
Table 1. The highest occupied molecular orbital energies (EHOMO), the lowest unoccupied
Indigo
-2.77
-5.27
Thioindigo
-3.05
-5.86
Selenoindigo
-3.02
-5.69
Dichloroindigo
-3.08
-5.63
Tetrabromoindigo
-3.26
-6.79
cr
ELUMO
us
EHOMO
an
Dye
ip t
molecular orbital energies (ELUMO).
M
Energies in eV.
When the frontier molecular orbital of all dyes is compared with the corresponding to metal oxides TiO2, ZnO and (ZnO)12 cluster, we can see easily in figure 2, which one can
d
work like photosensitizers, for each metal oxide. In this case no one is adapting to ZnO
te
bulk, but for (ZnO)12 cluster, the indigo can work, and maybe increase charge injection efficiency (CIE) owing to the closely LUMO level. For TiO2 Tetrabromoindigo dye may
Ac ce p
work better, for CIE, even the difference HOMO donator LUMO acceptor help to avoid electron recombination. The other dye can work properly with TiO2, over all take in count the proximity HOMO level, but more negative, to reduction potential energy of the I−/I3− electrolyte.
Page 6 of 13
Figure 2. Schematic energies HOMO and LUMO diagram of dyes, Zinc Oxide, Titanium dioxide
-3.08
-6.83
Dichloroindigo
-5.69
-5.63
I-/I3-4.80
-6.79
Energies in eV.
b c
Theoretical data from Ref [14]
Ac ce p
a
te
d
-7.16
M
-5.86
Tetrabromoindigo
-5.78
us
-5.27
an
-4.04
-3.26
cr
-3.02
b
Indigo
TiO2
-3.05
Selenoindigo
(ZnO)12c -2.77 -2.79
-2.03
Thioindigo
ZnOa
ip t
and (ZnO)12 cluster, and electrolyte (I−/I3−).
Experimental data from [15]
Theoretical data from Ref [16].
One important factor, efficiency DSSC related, is the efficiency of the dye in response to the incident light. The light harvesting efficiency (LHE) of the dye was evaluated. This value most be the higher as possible to maximize the photocurrent response [17]. (1) Where A and ƒ are the absorption and oscillating strength, respectably, corresponding to absorption energy of the dye. TD-DFT underestimates the transition probabilities.
Page 7 of 13
The LHE was underweighted for this calculation. The values calculated for LHE has been showed in Table 2. In Table 2 are showed every vertical excited singlet states, transition energies and oscillating strength of all dyes. Each molecule show HOMO-LUMO transitions in λmax,
ip t
but just Indigo and Tetrabromoindigo show higher oscillating strength in this
transition. The first vertical excitation energies (ΔEexcit), corresponding to HOMO-LUMO
cr
transition, is showing, even the only other transition, which for Thioindigo,
us
Selenoindigo and Dichloroindigo had the higher oscillating strength.
Table 2.
an
The vertical singlet states, transition character, oscillating strength of the absorption bands in UV–vis region for all dyes; plus light harvesting efficiency (LHE).
Thioindigo
Energiesb
536.2 321.2
Transition characterc
LHE
2.31
0.2673
H-0→L+0(+70%)
0.460
3.86
0.2291
H-3→L+0(+85%)
0.410
2.43
0.1964
H-0→L+0(+98%)
0.364
3.85
0.202
H-3→L+0(+93%)
0.372
547.4
2.26
0.1697
H-0→L+0(+99%)
0.323
323.4
3.83
0.1897
H-4→L+0(+94%)
0.354
525.4
2.36
0.2973
H-0→L+0(+100%)
0.496
345.3
3.59
0.3578
H-3→L+0(+96%)
0.561
533.4
2.32
0.3934
H-0→L+0(+100%)
0.596
363.6
3.41
0.2215
H-2→L+0(+97%)
0.400
510.7
M
ƒ
d
Indigo
λa
te
Dye
Ac ce p
321.8 Selenoindigo
Dichloroindigo
Tetrabromoindigo a
In nm.
b
In eV.
c
Major contribution to the transitions are in parenthesis.
Page 8 of 13
According to LHE, Tetrabromoindigo is the most efficient, follow for Dichoroindigo and Indigo. From this, we can assume that substitutes of H can increase the properties of Indigo derivates dyes for their use in DSSC. This can be subject for other work. Conclusions
ip t
Each of the molecules was theoretically analyzed. According to thermodynamic, the spontaneous charge transfer process from the dye in excited state to the conduction
cr
band of metal oxide, need that the LUMO energy of the dye be more positive potential than conductive band energy of the metal oxide, while the HOMO energy of the dye
us
most be more negative than reduction potential energy of the I−/I3− electrolyte. The calculations show that all dyes can work for DSSC with TiO2, because all have LUMOS
an
less negative than TiO2 LUMO, while no one have less negative HOMO than the redox potential energy of electrolyte; no one can work with ZnO, and just Indigo can work with (ZnO)12, Tetrabromoindigo have the higher LHE of this dyes, which one we
Acknowledgements
d
M
recommended for DSCC with TiO2; we expect that these dyes will be tested for DSSC.
te
This work has been partially supported by Consejo Nacional de Ciencia y Tecnología
Ac ce p
(CONACYT, Mexico). FCN gratefully acknowledges a fellowship from CONACYT. DGM is a researcher with CONACYT and CIMAV.
References [1]
L. Serrano-Andrés, B. O. Roos, A Theoretical Study of the Indigoid Dyes and
Their Chromophore, Chemistry – A European Journal 3 (1997) 717–725. [2]
P. Süsse, M. Steins, V. Kupcik, Indigo: Crystal structure refinement based on
synchrotron data, Zeitshrift fü Kristallographie 184 (1988) 269–273. [3]
J. Tomkinson, M. Bacci, M. Picollo, D. Colognesi, The vibrational spectroscopy of
indigo: A reassessment, Vibrational Spectroscopy 50 (2009) 268-276. [4]
Z. C. Koren, High-performance liquid chromatographic analysis of an ancient
Tyrian Purple dyeing vat from Israel, Israel Journal of Chemistry 35 (1995) 117-124.
Page 9 of 13
[5]
H. Bauer, K. Kowski, H. Kuhn, W. Lüttke, P. Rademacher, Photoelectron spectra
and electronic structures of some indigo dyes, Journal of Molecular Structure 445 (1998) 277-286. [6]
T. Karapanayiotis, S. E. Jorge-Villar, R. D. Bowen, H. G. M. Edwards, Raman
ip t
spectroscopic and structural studies of indigo and its four 6,6′-dihalogeno analogues, Analyst 129 (2004) 613–618.
P. Süsse, G. Kunz, W. Lüttke, Zur Kristallstruktur des Selenoindigos,
cr
[7]
Naturwissenschaften 60 (1973) 49-50.
W. Haase-Wessel, M. Ohmasa, P. Süsse, Thioindigo: Crystal structural data for
modification II, Naturwissenschaften 64 (1977) 435.
M. I. G. M. G. Travasso, P. C. Santos, A. M. F. Oliveira-Campos, Indigo revisited,
an
[9]
us
[8]
Advances in Colour Science and technology 6 (2003) 95-99.
M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R.
M
[10]
Cheeseman, J.A. Montgomery, Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S.
d
Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Ukuda, J. Hasegawa, M.
te
Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox, H.P.
Ac ce p
Hratchian, J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M. C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Anayakkara, M. Challacombe, P.M. W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A. Pople: Gaussian 03, Revision B.05, Pople, Gaussian, Inc., Pittsburgh PA, 2003. [11]
E. A. Perpète, D. Jacquemin, TD-DFT benchmark for indigoïd dyes, Journal of
Molecular Structure: THEOCHEM 914 (2009) 100-105. [12]
J. Tomkinson, M. Bacci, M. Picollo, D. Colognesi, The vibrational spectroscopy of
indigo: A reassessment, Vibrational Spectroscopy 50 (2009) 268–276.
Page 10 of 13
[13]
S.I. Gorelsky, SWizard program 2011. University of Ottawa, Ottawa, Canada,
Available from http://www.sg-chem.net/. [14]
S. Nénon, R. Méreau, S. Salman, F. Castet, Van Regemorter T., Clima S.,
Beljonne D., Cornil J., Structural and Electronic Properties of the TTF/ZnO(10–10)
ip t
Interface: Insights From Modeling, The Journal of Physical Chemistry Letters 3 (2012) 58-63.
J. B. Asbury, Y. Q. Wang, E. Hao, H. N. Ghosh, T. Lian, Evidences of hot excited
cr
[15]
state electron injection from sensitizer molecules to TiO2 nanocrystalline thin films,
[16]
us
Research on Chemical Intermediates 27 (2001) 393-406.
M. A. Flores-Hidalgo, D. Barraza-Jimenez, D. Glosmman-Mitnik, Effects of sulfur
an
substitutional impurities on (ZnO)n clusters (n = 4–12) using density functional theory, Computational and Theoretical Chemistry 965 (2011) 154-162. H. S. Nalwa, Handbook of Advanced Electronic and Photonic Materials and
Ac ce p
te
d
Devices; Academic: San Diego, 2001.
M
[17]
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Graphical Abstract (for review)
us
cr
A) Indigo
ip t
Optimized structure of all molecules included chemical symbol and label of Atoms.
C) Selenoindigo
Ac ce p
te
d
M
an
B) Thioindigo
D) Dichloroindigo
E) Tetrabromoindigo
Page 12 of 13
Highlights Each of the molecules was theoretically analyzed as potential photosensitizers
ip t
for DSSC. The calculations show that all dyes can work for DSSC with TiO2 and no one can
cr
work with ZnO.
us
No one have less negative HOMO than the redox potential energy of electrolyte.
Ac ce p
te
d
M
an
We expect that these dyes will be tested for DSSC.
Page 13 of 13