Design high-efficiency organic dyes based on fluorescein toward dye-sensitized solar cells: a DFT/TD-DFT study

摘要

The series of dyes derived from the fluorescein "2-(3-hydroxy-6-oxo-6Hxanthene-9-yl) benzoic acid" with introduction of different acceptor functional groups at the para position were designed as material sensitizers for solar cells. DFT and TD-DFT with B3LYP hybrid function at 6-31G (d,p) basis set were simulated to investigate the significant properties of all isolated dyes together with utilizing a Lanl2DZ basis set of titanium atom of dyes adsorbed on a TiO2 as complex systems in the gas phase at the ground and excited state. The resulted values of electronic parameters such as HOMO, LUMO levels, energy gap and dipole moment of the dyes can be employed to improve the efficient dyes of solar cell. The range of the energy of HOMO was from - 4.903 to - 6.258 eV, LUMO from - 3.010 to - 2.727 eV, the energy gab from 3.539 to 1.926 eV, and the dipole moment from 9.306 to 11.627 Debye of all dyes. The calculated data demonstrated better electronic properties, driving force, chemically reactivity, open-circuit photo-voltage, redox, light harvesting efficiency, oscillator strength, light absorption spectra, electron injection, oxidation potential energy and electron regeneration. Moreover, the favored dye charge transfer and adsorption process on model, including dye-oxide couple (Ti(OH)(3)H2O) was examined. The calculations which were based on the DFT method showed excellent photoelectric conversion efficiency and strong binding of the dyes on the surface of TiO2. Additionally, there is a probability that the electron injection process happening from each examined molecule to the conduction band of TiO2 and the succeeding regeneration. As a result, the theoretical results can be useful for to synthesize novel, highly photo- effective materials and can play the significant role of sensitizers in DSSC applications.