Molecular design of coumarin dyes with high efficiency in dye-sensitized solar cells

Density functional theory (DFT) and time-dependent DFT calculation have been applied to study the coumarin dyes which act as photosensitizer in dye-sensitized solar cells. The absorption spectra of coumarin dyes in ethanol can be well reproduced with theoretical method. The outstanding performance of NKX-2311 roots in higher light harvesting efficiency and more efficient electron injection efficiency into conduction band of TiO2 electrode according to our computation. Absorption peaks and HOMO energy levels of dyes can be employed as the two effective theoretical parameters for the judgement of their solar to energy efficiency. New coumarin dyes which probably possess higher efficiency were designed referring to our conclusions. (C) 2007 Elsevier B.V. All rights reserved.