Theoretical Study of New Ruthenium-Based Dyes for Dye-Sensitized

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Theoretical Study of New Ruthenium-Based Dyes for Dye-Sensitized Solar Cells Antonio Monari,*,† Xavier Assfeld,† Marc Beley,‡ and Philippe C. Gros‡ †

Equipe de Chimie et Biochimie Theoriques and ‡Groupe SOR, SRSMC-UMR 7565, Institut Jean Barriol, Nancy Universite, BP 70239, 54506 Vandoeuvre-les-Nancy, Cedex France ABSTRACT: Two relevant, recently reported, rutheniumbased complexes to be used as sensitizers in Gr€atzel photovoltaic cells are theoretically studied. The UV/vis absorption spectra have been computed within the time-dependent density functional theory formalism. The obtained excitation energies are compared with the experimental results, and the nature of the transition is analyzed in terms of the electronic density. A preliminary study on the performance of different functionals against the equation of motion coupled cluster is performed on a smaller model system.

1. INTRODUCTION Following the seminal paper of Gr€atzel et al., published in 1991,1 the possibility to use dye-sensitized solar cells (DSC) has emerged as a realistic alternative to silicon-based devices.211 In contrast with solid-state silicon devices, DSC cells are, indeed, based on complex molecular components that are able to harvest the energy coming from sunlight to produce electricity.11 The complex mechanism characterizing these devices, as well as the presence of sensitizers and chromophores, makes them known as being able to reproduce a sort of artificial photosynthesis. If the definition can be seen as somehow emphatic, especially bearing in mind all of the subtleties of the photosynthetic process, it gives an idea of the complexity and of the interplay of the different chemical and physical mechanisms. In any case, today, the commercial production of DSC is a well-established reality,11 and performances of DSC, even if lower than silicon-based cells, have become extremely interesting. For instance, performances of about 12% are recorded for small cells.11 Moreover DSC are known to outperform conventional solid-state methods in indoor conditions or in the presence of diffuse light conditions and high temperature.11 Most important, the DSC production process is much cheaper and simpler than the one required for conventional solid-state devices, the latter requiring an expensive and energy-consuming silicon crystallization. As a consequence, pay-back time for DSC is becoming increasingly competitive, ranging from 1.3 years in Northern Europe to less than 1 year in Southern regions.11 One should add the fact that DSC offer the possibility to design cells with a large flexibility in shape, color, and transparency, thus opening the way to the integration in a wide range of commercial products.11 The principle behind DSC functioning is to harvest photon energy coming from sunlight by means of a chromophore (the dye) grafted onto a nanoporose semiconductor surface (usually r 2011 American Chemical Society

TiO2).1 Upon electronic excitation, the dye is able to inject one electron into the semiconductor conduction band. In the cell, a redox mediator will regenerate the dye and will then be regenerated at its turn at the counter electrode, therefore allowing for a charge transport in the liquid phase. In order to maximize the performance of DSC, several factors have to be taken into account,12,13 the role of the sensitizing dye being an essential one. Efficient dyes should harvest a significant portion of the visible light spectrum, and their excited states should ensure an efficient injection into the semiconductor, especially versus the possible recombination and the possible oxidation of the excited state by the redox mediator; on the other hand, the reduction of the oxidized dye (regeneration) should be as efficient as possible. It appears therefore clear that the proper choice of dye is crucial in the efficient design of photovoltaic cells. More recently, the role of a proper choice of the couple dye/ mediator has been evidenced too.13 The importance of the subjects of DSC is also highlighted by the increasing number of theoretical papers dealing with the subject.1422 In the same way, recently, the role of aggregation of dyes has been underlined.1923 The most widely used dyes rely on ruthenium-based complexes. One particularly important family is the one characterized by a general structure of the form RuL(dcbpy)(NCS)2, where dcbpy (4,40 -dicarboxy-2,20 -pyridine) and L can be a general (usually bidentate) ligand. Among this family, the N3 dye Ru(dcbpy)2(NCS)2 is certainly the most known, and its performance is usually regarded as a benchmark for new dyes. Obviously, the possibility to modify the ligand L will open the way to an efficient tuning of the dye properties, in particular, the Received: February 1, 2011 Revised: March 7, 2011 Published: March 23, 2011 3596

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The Journal of Physical Chemistry A

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Figure 1. S1 and S2 dyes studied in this work.

absorption range, increasing the molar extinction coefficient and preventing injected electron recombination via charge separation. A range of dyes has been synthesized and characterized by some of us13,2325 (see Figure 1). Among them, S1 bearing an extended pyrrole ligand and S2 characterized also by the presence of a styryl group have been found as the most promising. The two pyrrole-containing complexes S1 and S2 are interesting dyes for several reasons. The pyrrole bound by its nitrogen atom to the bipyridine ligand brings electron-donating effects. The consequence is an increase of the energetic level of the ruthenium complex HOMO orbital allowing the MLCT transition to occur at lower energy and thus leading to red-shifted absorption of light. Additionally, π-electrons of pyrrole contribute to an increase of the molar extinction coefficient. The π-delocalization in S2 led to an extended absorption domain even better than those of the standard dye N3 (Ru(dcbpy)2(NCS)2).26 The photolectrochemical study of these two dyes also revealed the critical role of the redox mediator. Indeed, S1 displayed better IPCE (incident photon-to-current efficiency) values than S2 in the presence of the Co(DTB)32þ/Co(DTB)33þ couple (DTB = 4,40 -diterbutyl-2,20 -bipyridine) (IPCE 62%), while S1 gave a better performance in the presence of the I/I3 couple (IPCE 75%).13 Finally, pyrroles can be polymerized electrochemically, and we have shown their possible application in solid-state devices.27,28 To optimize the performance of the DSC based on these dyes, we decided to set up a predictive approach of dye electronic properties in order to design new structures in a rational and straightforward way. In this contribution, we perform a theoretical study of the excited state and of the spectroscopic properties of these two dyes by using time-dependent density functional theory (TDDFT) methodologies. Because, in many cases, the electronic transition in the visible range of the light spectrum involves metalligand charge-transfer (MLCT) excitations, a preliminary benchmark of the performance of different functionals will be presented against the equation of motion coupled cluster (EOM-CC) realized on a smaller model system. A detailed and rational analysis of the excited state in terms of electronic density difference will also be presented. The present contribution is organized as follows. In section 2, computational details will be presented, in section 3, the performance of the different functionals will be briefly analyzed, and in

section 4, we will present and discuss our results. We will draw our conclusions in section 5.

2. COMPUTATIONAL DETAILS AND STRATEGY All computations on the present work have been performed by using Gaussian0329 and Gaussian0930 codes. All of the geometries have been optimized at the density functional (DFT) level by using B3LYP hybrid functional.31 For the geometry optimization, a LANL2DZ basis set developed by Dunning et al.32 was used for the first-row atoms. In the case of heavier atoms (ruthenium and sulfur), the LANL2DZ basis set included an electron core pseudopotential (ECP) as developed by Hay et al.3335 In order to study the effect of the basis size and quality, excitedstate energies have been computed at the TDDFT level by using also the LAN2TZ plus ECP basis set on a Ru atom3335 and the 6-311þG or 6-311þG* basis36 on ligands. Because the interesting part of the UV/vis spectrum is characterized by the presence of a charge-transfer transition (mainly of metal-to-ligands type), we used different long-range corrected functionals in order to recover the long-range 1/R behavior. In particular, CAMB3LYP37 has been extensively used;some tests have been performed by using LC-PBE038 and wB97XD39 functionals. The performance of different functionals has been briefly assessed by comparing their behavior against EOM-CC to the single and double excitations (EOM-CCSD)40 on a model system. In the computation of the UV/vis spectra, the solvent effects (acetonitrile) have been included by using the PCM continuum model.4144 The nature of the main excitation has been analyzed in terms of electron density reorganization by using the attachment/ detachment density (ADD) formalism.45,46 The ADD formalism is based on the analysis of the difference density matrix Δ, that is, the difference of the values of the density matrix between the ground and an excited state. Indeed, it is possible to diagonalize the Δ matrix by means of a proper unitary transformation U T ΔU ¼ δ Subsequently, one can separate the positive and negative occurrences in the diagonal matrix Δ and therefore define two new diagonal matrices a and d di ¼ minðδi , 0Þ ai ¼ maxðδi , 0Þ By means of the unitary back-transformation, one can obtain the 3597

dx.doi.org/10.1021/jp201058v |J. Phys. Chem. A 2011, 115, 3596–3603


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two square matrices A and D A ¼ UaU T

D ¼ UdU T

where A is defined as the attachment density matrix and D as the detachment density matrix. Note that A and D are two positive semidefinite matrices (because the sign has been changed for d), and therefore, they have positive entries everywhere. In more physical terms, the detachment matrix corresponds to the electron density of the ground state that is removed in the excitation (and therefore, it can be seen as a sort of “hole” density). The attachment matrix on the other hand corresponds to the part of the electron density that is rearranged in the excited state (a sort of “particle” density). Even if the physical information contained in the difference density or in D and A matrices is the same, the possibility to separate the two contributions and the absence of nodal surfaces make the analysis of the transition much easier.

3. FUNCTIONALS BENCHMARKING Because, as already stated, the electronic transition observed in ruthenium-based organometallic dyes often involves charge-transfer excitation, mainly of MLCT or ligand-to-ligand (LLCT) type, we decided to first analyze the behavior of different functionals, mainly long-range corrected, regarding their ability to correctly reproduce such phenomena. However, here, we do not want to perform a systematic and complete benchmark, whose scope will be far beyond the objectives of the present contribution; rather, we just want to give a preliminary assessment of the performance of different functionals. In order to use high-accuracy wave-function-based ab initio methods, a model system reproducing some of the characteristics of the real dyes was chosen. Following the work of Guillon et al.,47 we considered the [Ru(dab)3]2þ cation, where dab is the

1,4-diaza-1,3-butadiene (see Figure 2), the simplest ligand of the diimine family. The geometry of the dication has been previously optimized at the DFT level with the B3LYP functional and the LANL2DZ basis set. Starting from the equilibrium geometry, excited states have been computed by using TD-DFT and four functionals, the usual B3LYP and three long-range corrected ones (CAM-B3LYP, LCPBE0, and wB97XD). TD-DFT results have been compared with EOM-CCSD ones. In Figure 3, we report the UV/vis spectrum obtained (note that the form of the spectrum has been obtained by superimposing a Gaussian function with a fixed half-length width of 100 nm), while the most important transitions in terms of the oscillator strength are listed in Table 1. Note that in the case of TD-DFT computations, we computed 20 singlet excited states, while only 10 states have been requested for the EOM-CCSD computation. As can be seen from Figure 3, relatively good agreement can be found in the description of the peak centered at about 375 nm, even if B3LYP functionals induce a red shift and LC-PBE a blue shift as compared to EOM-CCSD. The difference in intensity with coupled cluster results is due to the fact that at this level of theory, a smaller number of transitions has been computed. On the other hand, as expected, B3LYP appears to not be strongly adapted to correctly reproduce the low-energy transition, that is, the MLCT region. If this is a rather well-known fact, it also appears that a rather great variability between the long-range corrected functional results is still present. Therefore, if the CAM-B3LYP and wxB97 results are in very good agreement with EOM-CCSD ones, LC-PBE0 values are so blue-shifted that the peak becomes a shoulder on the main transition. These results, confirming the capability of the CAM-B3LYP functional to reasonably reproduce the charge-transfer transition,

Figure 3. Computed UV/vis spectrum of Ru(dab)3 dication (wavelengths in nm; intensities in arbitrary units).

Figure 2. Optimized structure of [Ru(dab)3]2þ.

Table 1. Most Important Electronic Transitions of [Ru(dab)3]2þ with Different Functionals and EOM-CCSDa

a

transition

B3LYP

CAM-B3LYP

xB97XD

LC-PBE0

EOM-CCSD

4

498.99 (0.02)

437.82 (0.03)

443.32 (0.04)

398.03 (0.06)

438.63 (0.06)

5

498.71 (0.02)

437.66 (0.03)

443.15 (0.04)

397.93 (0.06)

438.57 (0.07)

7 8

397.49 (0.16) 397.33 (0.16)

377.46 (0.17) 377.36 (0.17)

378.13 (0.16) 378.05 (0.16)

358.72 (0.15) 358.67 (0.16)

380.86 (0.12) 380.82 (0.12)

Wavelengths are in nm, and the oscillator strengths are given in parentheses. The transition index indicates the excited state involved in the transition. 3598



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Figure 4. CAM-B3LYP TD-DFT UV/vis spectra for the S1 dye. (Left) Isolated molecule; (right) in acetonitrile (wavelengths in nm; intensities in arbitrary units).

should also suggest that care should be taken in analyzing TDDFT computed spectra, at least in the case of the presence of difficult transition, due to the still important spread of the results. It is noteworthy anyhow to remark that due to the inverse proportionality relation between energy and wavelength λ, the same error on the energy produces a much larger effect on λ at longer wavelengths than it does at shorter wavelengths. For instance, a difference of 0.1 eV on the energy produces an error of 6 nm close to 300 nm and of 20 nm close to 500 nm. Although it is well-known that the B3LYP functionals proved to provide very good results, showing remarkable agreement with experimental data even in the case of charge-transfer states, at least in the case when the charge-transfer phenomenon is of short-range type,2022,47 we prefer to perform this study by using the long-range corrected CAM-B3LYP functional. Even if the latter requires a higher computational effort, the important delocalization of the charge-transfer state that can take place in our complexes, together with the results presented in this section justify this choice.

Figure 5. Experimental and computed S1 (TD-DFT, CAM-B3LYP) UV/vis spectra (wavelengths in nm; intensities in arbitrary units).

4. RESULTS AND DISCUSSION We present here the results obtained on the S1 and S2 dyes. All computations of excited states have been realized by using the CAM-B3LYP functional that proved efficient in the determination of the charge-transfer transition. The relative small size of the S1 dye allows for a rather systematic study of the influence of the basis set on the spectroscopic properties. Results obtained with the small LANL2DZ basis as well as the ones obtained with the LAN2TZ basis for ruthenium and 6-311þG or 6-311þG* for lighter atoms, respectively, are presented in Figure 4. As was done in the previous example, the computed spectra have been convoluted by using fixed-width Gaussian functions. In the left panel of Figure 4, we report the spectra obtained for the isolated molecule (gas phase), while in right panel, we included the effect of solvent (acenotrile) by using the PCM method. In the case of S1 dye, 35 excited states have been computed simultaneously, while 40 have been necessary for the S2 case. UV/vis Spectra. By analyzing the spectra reported in Figure 4, it appears evident that the effect of the basis set size, although present, is not of extreme importance. The smallest double-ζ basis is already able to reproduce at least qualitatively the general

shape of the spectrum. The difference between the two other triple-ζ quality sets is even less important. On the other hand, the inclusion of solvent effects does change in a very significant way the overall spectrum. The isolated molecule spectrum appears generally redshifted by about 100150 nm, and more importantly, even the shape and the qualitative behavior appears to be strongly affected. It is noteworthy that the inclusion of solvent effects determines the lowering of the long wavelength peak (at about 900 nm), whose intensity is reduced practically to 0. Apart from the quenching of this transition, the other low-frequency band (700 nm without solvent effects and 500 nm with PCM model) is also much more blue-shifted than the other transitions. If in the two cases one can see the appearance of three main peaks in the gas-phase case, the second one is much less resolved and almost looks like a shoulder on the main peak. In Figure 5, we report the comparison between the computed TD-DFT spectrum (with the LANL2TZ/6-311þG basis) and the experimental one in acetonitrile. From the comparison between the two spectra, one can see that the overall shape of the experimental spectrum with the three well-defined peaks is well reproduced. On the other hand, if 3599



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Figure 6. Experimental and computed S2 (TD-DFT, CAM-B3LYP) UV/vis spectra (wavelengths in nm; intensities in arbitrary units).

Figure 7. TDDFT spectrum of S1 dye with the B3LYP functional with solvent effects (wavelenghts in nm; intensities in arbitrary units).

the position of the peaks at about 300 and 400 nm are quite well reproduced, this is not the case for the last one, where a more important blue shift of about 75 nm is observed in the computed spectrum. Even if this effect can appear and indeed is important in terms of wavelengths, two important aspects should be recalled. First of all, as already mentioned, in the high-wavelength region, the wavelength differences are overestimated; actually, the observed shift in wavelength in the region of 500550 nm turns out to an energy difference of about 0.250.30 eV. Second, it has to be emphasized that in this region, the transitions are essentially of charge-transfer type, a fact that represents an additional issue for a TD-DFT treatment. In Figure 6, we present the theoretical and experimental results obtained for the S2 dye in the presence of acetonitrile. In this case, only the LANL2DZ and LANL2TZ/6311Gþ basis sets have been considered. Obviously, the general consideration invoked in the case of the S1 dye spectrum also applies in the present case. The passage from a well-resolved three-peaked structure to one where two peaks are less well-defined is correctly represented, even if, again, the low-energy peak suffers from a significant blue shift (of the same magnitude as that in the S1 case). The same arguments invoked previously can be used to rationalize this discrepancy. Our computed spectra can also be compared with spectra calculated by using the B3LYP functional for the S1 dye (Figure 7). It is remarkable to see that B3LYP induces a high-intensity spurious peak in the region of the near-infrared wavelengths. Moreover, even if, using the LANL2TZ/6-311Gþ basis set, the position of the peak at about 400 nm is correctly represented, the first MLCT peak appears red-shifted by about 75 nm. This shift is slightly higher than the one obtained at the CAM-B3LYP level. It should also be emphasized that the B3LYP results appear to be much more sensitive to the choice of the basis set; for instance, the LANL2DZ basis shows a MLCT peak red-shifted by about 90 nm with respect to the LANL2TZ/6-311Gþ computations. This point clearly show that CAM-B3LYP outperforms B3LYP for the complexes that are the subject of this study. Excited-State Analysis. We report here the analysis in terms of the ADD electron density of the principal transitions. In Table 2, we show the wavelength of the transitions whose oscillator force is higher or at least equal to 0.1 for S1 and S2

Table 2. TD-DFT Principal Transitions, Wavelength, and Oscillator Strengtha S1

S2

transition

λ (nm)

f

transition

λ (nm)

f

3

477.31

0.1

3

480.08

0.3

5

405.09

0.1

4

455.78

0.1

7

384.97

0.1

5

414.21

0.3

17

312.61

0.1

7

382.8

0.2

19

303.54

0.1

9

357.38

1.2

20 28

295.80 278.44

0.1 0.4

12 27

337.85 285.43

1.1 0.2

30

272.09

0.2

28

284.64

0.1

30

279.24

0.2

36

269.20

0.1

a

The transition index indicates that the excited state is involved in the transition.

computed with the LANL2TZ/6-311þG basis set in the presence of solvent. One can immediately note that the transitions in S2 are of much higher intensity than those in S1, an occurrence that is confirmed also experimentally.13 The DA densities are presented in Figurea 8 and 9 for S1 and S2 complexes, respectively. One can immediately notice that the transition centered around 500 nm (transition 3) is of MLCT type. The resulting density in the excited state is preferentially pushed in the dcbpy moiety. This can be an important aspect in their application as photosensitizers because the dbcpy will be directly grafted onto the semiconductor surface. An accumulation of “particle” density close to the surface will of course favor the electron injection process. It is, however, important to emphasize the role played by the NCS ligand group. A significant amount of electron density is detached from the NCS group; moreover, the two ligands do not participate equally. In transition 3, only the NCS perpendicular to the dcbpy group is involved, while the coplanar NCS does not participate. Also, the transition centered around 400 nm (transitions 5 and 7) involves MLCT charge-transfer phenomena, again with a strong participation of the NCS groups. In contrast, 3600



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Figure 9. Detachement (left) and attachment (right) densities for the S2 dye.

Figure 8. Detachement (left) and attachment (right) densities for the S1 dye.

in transition 5, the NCS group participating in the detachment density is the coplanar one with respect to the dcbpy ligand; the corresponding attachment density is, on the other hand, pushed on the pyrrol ligand. In the photovoltaic context that could signify that for this excited state, the electron injection could be more difficult because the particle density will be pushed far from the semiconductor surface, recombination phenomena and oxidoreduction exchange with the redox mediator could become more important. Transition 7 on the other hand shows the participation of both NCS groups in the detachment density while the attachment density is centered on the dcbbpy moiety. Finally, as far as the region of 300 nm is concerned, one can see that LLCT transitions are certainly present (see transition 30 for instance), but more surprisingly, the region appears quite complex with the presence of MLCT or mixed MLCT þ LLCT transitions (see transition 20). The same considerations can be applied to the S2 dye, whose selected transitions are analyzed in Figure 8. Once again, it is evident how the transition at about 500 nm (transition 3) is of MLCT type with a strong participation of the NCS group while the attachment density is centered on the dcbpy unit. Also, once again, the NCS perpendicular to

the dcbpy ligand has a predominant role. In the region of about 400 nm (transitions 5 and 7), one can still see a predominant MLCT character; as in the S1 dye, one transition (in this case, number 5) centers the attachment density on the styrril ancillary ligand, while the other one (transition 7) draws density toward the dcbpy ligand. Even if it is less evident than that for the previous system, the role of the NCS ligand is similar, and a predominance of the NCS coplanar to the dcbpy is observed in transition 5, while transition 7 shows a more equivalent participation. At shorter wavelengths, one can again find some complicated mixed MLCT þ LLCT transition (see, for instance, transitions 9 and 12).

5. CONCLUSIONS We have performed a detailed TD-DFT analysis of the UV/vis spectral properties of two new ruthenium-based dyes for Gr€atzel photovoltaic cells. The influence of the basis set and of different functionals has been evaluated, in particular, with respect to their capability to correctly reproduce MLCT-type electronic transition. The computed spectra show good agreement with experimental data, provided that one uses long-range corrected functionals and solvent effects are taken into account. The transitions have been analyzed with regard to the change induced in the electronic density. The influence and the very important role played by the two NCS groups have been evidenced. Remarkably, it has been proven that the two NCS groups do not participate in the same way. In particular, while one of the two tends to favor transitions that could make charge injection easier, the other one draws electronic density away from the COOH anchoring groups, therefore impeding the charge-transfer process. It 3601


The Journal of Physical Chemistry A has also to be emphasized how MLCT and mixed LLCT transitions can be found also in the UV region of the spectrum. These results are of great importance to favor a rational design of new dyes in which the electronic transition nature could be tuned by a proper choice of ligands. We plan to extend this first study by considering the effect of the grafting to a TiO2 cluster on the electronic transition and on the charge-transfer process also by using mixed hybrid QM/MM techniques; this will give an even deeper insight into the process governing this critical step in the Gr€atzel cells' operating scheme. Another interesting perspective could arise from the determination of UV/vis spectra in an ionic liquid environment. The latter are rapidly emerging as promising solvents in DSC technologies. Their low dielectric constant could induce a significant red shift of the UV/vis absorption compared to that of acetonitrile and, therefore, a gain in performance. Even though, the effects on the mediator mobility should be taken into account carefully.

’ AUTHOR INFORMATION Corresponding Author

*E-mail: [email protected].

’ ACKNOWLEDGMENT Support from Nancy Universite and CNRS is gratefully acknowledged; we also acknowledge financing of the “chaire d’excellence”. X.A. and A.M. acknowledge support from the ANR Project ANR-09-BLAN-0191-01 “PhotoBioMet”. A.M. thanks the CALMIP computer centers for the opportunity to use their computing resources. ’ REFERENCES (1) O’Regan, B. C.; Gr€atzel, M. Nature 1991, 353, 737. (2) Hagfeldt, A.; Gr€atzel, M. Chem. Rev. 1995, 95, 49. (3) Hagfeldt, A.; Gr€atzel, M. Acc. Chem. Res. 2000, 33, 269. (4) Gr€atzel, M. Nature 2001, 414, 338. (5) Gr€atzel, M. Inorg. Chem. 2005, 44, 6841. (6) Ardo, S.; Meyer, G. J. Chem. Soc. Rev. 2009, 38, 115. (7) Peter, L. M. J. Phys. Chem. C 2007, 111, 6601. (8) Peter, L. M. Phys. Chem. Chem. Phys. 2007, 9, 2630. (9) Bisquert, J.; Cahen, D.; Hodes, G.; Ruhle, S.; Zaban, A. J. Phys. Chem. B 2004, 108, 8106. (10) O’Regan, B. C.; Durrant, J. Acc. Chem. Res. 2009, 42, 1799. (11) Hagfeldt, A.; Boschloo, G.; Sun, L.; Kloo, L.; Pettersson, H. Chem. Rev. 2010, 110, 62595. (12) Robertson, N. Angew. Chem., Int. Ed. 2006, 45, 2338. (13) Grabulosa, A.; Martineau, D.; Beley, M.; Gros, P. C.; Cazzanti, S.; Caramori, S.; Bignozzi, C. A. Dalton Trans. 2009, 63. (14) Preat, J. J. Phys. Chem. C 2010, 114, 16716. (15) Preat, J.; Jacquemin, D.; Perpete, E. A. Energy Environ. Sci. 2010, 3, 891. (16) Preat, J.; Jacquemin, D.; Michaux, C.; Perpete, E. A. Chem. Phys. 2010, 376, 56. (17) Preat, J.; Jacquemin, D.; Perpete, E. A. Environ. Sci. Technol. 2010, 44, 5666. (18) Preat, J.; Michaux, C.; Jacquemin, D.; Perpete, E. A. J. Phys. Chem. C 2009, 113, 16821. (19) Pastore, M.; De Angelis, F. ASC Nano 2010, 4, 556. (20) Fantacci, S.; De Angelis, F.; Selloni, A. J. Am. Chem. Soc. 2005, 125, 16835. (21) De Angelis, F.; Fantacci, S.; Selloni, A.; Gr€atzel, M.; Nazeruddin, M. K. J. Am. Chem. Soc. 2007, 129, 14157.

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(22) Lundqvist, M. J.; E. Galoppini, E.; Meyer, G. J.; Persson, P. J. Phys. Chem. A 2007, 111, 1487. (23) Jacquemin, D.; Perpete, E. A.; Laurent, A. D.; Assfeld, X.; Adamo, C. Phys. Chem. Chem. Phys. 2009, 11, 1258. (24) Martineau, D.; Beley, M.; Gros, P. C.; Cazzanti, S.; Caramori, S.; Bignozzi, C. A. Inorg. Chem. 2007, 46, 2272–2277. (25) Grabulosa, A.; Beley, M.; Gros, P. C.; Cazzanti, S.; Caramori, S.; Bignozzi, C. A. Inorg. Chem. 2009, 48, 8030–8036. (26) Nazeeruddin, M. K.; Wang, Q.; Cevey, L.; Aranyos, V.; Liska, P.; Figgemeier, E.; Klein, C.; Hirata, N.; Koops, S.; Haque, S. A.; Durrant, J. R.; Hagfeldt, A.; Lever, A. B. P.; Gr€atzel, M. Inorg. Chem. 2006, 45, 787–797. (27) Caramori, S.; Cazzanti, S.; Marchini, L.; Argazzi, R.; Bignozzi, C. A.; Martineau, D.; Gros, P. C.; Beley, M. Inorg. Chim. Acta 2008, 361, 627. (28) Grabulosa, A.; Beley, M.; Gros, P. C. Inorg. Chim. Acta 2010, 363, 1404. (29) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, revision C.02; Gaussian, Inc.: Wallingford, CT, 2004. (30) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, P. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, € Ortiz, J. V.; Cioslowski, J.; Fox, D. J. S.; Daniels, A. D.; Farkas, O.; Gaussian 09, revision A.1; Gaussian, Inc.: Wallingford, CT, 2009. (31) Becke, A. D. J. Chem. Phys. 1993, 98, 5648. (32) Dunning Jr., T. H.; Hay, P. J. In Modern Theoretical Chemistry; Schaefer, H. F., III, Ed.; Plenum; New York, 1976; Vol. 3, pp 128. (33) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 270. (34) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 284. (35) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 299. (36) R. Krishnan, R.; Binkley, J. S.; Seeger, R.; Pople, A. J. J. Chem. Phys. 1980, 72, 650. (37) Yanai, T.; Tew, D.; Handy, N. Chem. Phys. Lett. 2004, 393, 51. (38) Tawada, Y.; Tsuneda, T.; Yanagisawa, S.; Yanai, T.; Hirao, K. J. Chem. Phys. 2004, 120, 8425. (39) J.-D. Chai, J.-D.; Head-Gordon, M. Phys. Chem. Chem. Phys. 2008, 10, 6615. (40) Koch, H.; Jørgensen, P. J. Chem. Phys. 1990, 93, 3333. (41) S. Miertus, S.; Scrocco, E.; Tomasi, J. Chem. Phys. 1981, 55, 117. (42) M. Cossi, M.; Barone, V.; Cammi, R.; Tomasi, J. Chem. Phys. Lett. 1996, 255, 327. (43) M. Cossi, M.; Barone, V. J. Chem. Phys. 2000, 112, 2427. 3602



ARTICLE

(44) Cossi, M.; Barone, V. J. Chem. Phys. 2001, 115, 4708. (45) Head-Gordon, M.; Grana, A. M.; Maurice, D.; White, C. A. J. Phys. Chem. 1995, 99, 14261. (46) Dreuw, A.; Head-Gordon, M. Chem. Rev. 2005, 105, 4009. (47) Guillon, T.; Boggio-Pasqua, M.; Alary, F.; Heully, J.-L.; Lebon, E.; Sutra, P.; Igau, A. Inorg. Chem. 2010, 49, 8862.

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