Estudo computacional das propriedades eletrônicas de complexos polipiridínicos de rutênio(ii) com potencial aplicação em células solares sensibilizadas por corante

Abstract

The search for renewable energy sources grows increasingly in many regions of the world due to the crescent demand and pollution generated by the use of fossil fuels.The solar energy is a renewable and endless source of energy, which may be harnessed directly with different types of solar cells. Among thesevaried types, the dye-sensitized solar cells (DSSCs) present themselves to be promising owing to their high efficiency. Fromthe many molecules used as sensitizers in this kind of cell, the most efficient are thepolypyridinicruthenium(II) complexes. Different properties are important for a molecule to be applicable in a DSSC as an efficient sensitizer, among them a broad and intense absorption in the visible and near infrared region of the electromagnetic spectrum and a redox potential that allows the sensitizer to be regenerated by the redox couple,that is also part of the cell. In this work wasbuilt a computational methodologybased on experimental datawhich gives results with small deviations, for the calculation of redox potentials and electronic spectra of complexes cis-[Ru(R2-phen)(dcbpy)(NCS)2], where dcbpy is the4,4’-dicarboxylic acid 2,2’-bipyridineandR2-phenthe1,10-phenanthrolinewith R substituents on the positions 4 and 7. For the calculation of redox potentials, was applied the density functional theory (DFT) and for the electronic spectra simulations, the time-dependent DFT (TDDFT). With this methodology, new complexes where evaluated and their properties studied intending to estimate their efficiencies if applied to DSSCs. The new complexes that presented better results, in order from the less to the most promising, were those with substituents R = 2-pyridyl, 2-(5-ethylfuryl) and 2-benzothiazolyl.