Theoretical studies on structural and spectroscopic properties of photoelectrochemical cell ruthenium sensitizers, derivatives of AR20

Abstract

Special efforts were devoted to improve the absorption behavior of AR20 in visible region. Density functional theory (DFT)‐based approaches were applied to explore the electronic structure properties of AR20 and its derivatives. Time‐dependent DFT results indicate that the ancillary ligand controls the molecular orbital (MO) energy levels and masters the absorption transition nature. The deprotonation of anchoring ligand not only affects the frontier MO energy levels but also determines the energy gaps of highest occupied MO–lowest unoccupied MO (LUMO) and LUMO–LUMO+1. Introducing thiophene groups into ancillary ligands would enhance the efficiency of the final dye‐sensitized solar cell (DSSC). The absorption intensity of the thiophene substituted derivatives of AR20 is irrelevant with environment circumstance change, such as pH value. This special nature prognosticates the thiophene‐substituted derivatives of AR20 which would have a broad application in DSSC. © 2012 Wiley Periodicals, Inc.

Function of Tetrabutylammonium on High-Efficiency Ruthenium Sensitizers for Both Outdoor and Indoor DSC Application

“…Replacing the acidic H + in the sensitizer with TBA + provides an alternative method to optimize cell performance with less amount of TBP used. DUY11 containing one H + and one TBA + was used as a sensitizer to optimize the thickness of the TiO 2 films because the previous reports ,− indicate that a ruthenium sensitizer containing one TBA + ion generally has the highest efficiency among other H + /TBA + analogues. The photovoltaic parameters of the devices using the various thicknesses of TiO 2 photoanodes are summarized in Table .…”

“…Apart from the sensitizers containing four (N3) or three (N749) carboxylic acid anchoring groups, there are a large number of heteroleptic ruthenium sensitizers containing only one bipyridine anchoring ligand (which has two carboxylic acid anchoring groups on the ligand). 12−18 Nevertheless, to the best of our knowledge, there are only very few studies 19−21 related to the relationships between the degree of protonation and the physicochemical properties of those heteroleptic sensitizers, but no detailed systematic study on their relative photovoltaic performance was reported. We had reported previously that DSC sensitized with a heteroleptic ruthenium dye containing one TBA + and one H + in the anchoring ligand (named CYC-B11) achieves the efficiency of 11.5%, 3 whereas its full protonated form (named as CYC-B11H) showed an inferior photovoltaic performance (PCE of 9.64%).…”

“…N749, another representative ruthenium-based sensitizer, which has three carboxylic acid groups in one tridentate anchoring ligand, was also studied by Nazeeruddin et al It was shown that a cell based on the monoprotonated version (two TBA + , one H + , complex 3) of N749 series dyes exhibits the efficiency of 10.4% (under standard light illumination) which is higher than those of the cells based on triprotonated (complex 1), biprotonated (complex 2), and non-protonated (complex 4) versions. Apart from the sensitizers containing four (N3) or three (N749) carboxylic acid anchoring groups, there are a large number of heteroleptic ruthenium sensitizers containing only one bipyridine anchoring ligand (which has two carboxylic acid anchoring groups on the ligand). − Nevertheless, to the best of our knowledge, there are only very few studies − related to the relationships between the degree of protonation and the physicochemical properties of those heteroleptic sensitizers, but no detailed systematic study on their relative photovoltaic performance was reported. We had reported previously that DSC sensitized with a heteroleptic ruthenium dye containing one TBA + and one H + in the anchoring ligand (named CYC-B11) achieves the efficiency of 11.5%, whereas its full protonated form (named as CYC-B11H) showed an inferior photovoltaic performance (PCE of 9.64%) .…”

Theoretical studies on the quinoidal thiophene based dyes for dye sensitized solar cell and NLO applications

“…The B3LYP hybrid functional is one of the standard functionals and widely used to study the optoelectronic properties of the dye molecules. [45][46][47] The SWizard program 48,49 was used to simulate the absorption spectra of the molecules. The spectra were generated using the Gaussian function with a halfbandwidth of 3000 cm À1 as given in the following relation,…”

Design of high-performance chlorine type dyes for dye-sensitized solar cells

“…Furthermore, as is known, an appropriate dye sensitizer for DSSC, should have large absorption coefficient for solar spectrum, especially in the near‐IR and visible regions, good absorption on the surface of TiO 2 , and reasonable energy gap between highest occupied molecular orbital (HOMO)/LUMO. These are primary requirements for designing sensitizers for DSSC.…”