Theoretical study on the effect of solvents in chlorophyll solution for Dye-Sensitized Solar Cell

Using the density functional theory (DFT) and time-dependent DFT (TD-DFT), we have theoretically studied the electron excitation and absorption spectra of chlorophyll solution with several solvents for Dye-Sensitized Solar Cell (DSSC) application. The solvents were aceton, acetonitrile, DMSO, ethanol, hexane, methanol, THF and water. Also, energy level, oscilator strength, light harvesting efficiency and electron injection have been investigated. The studied dye in the presence of the solvents showed a smaller gap of the highest occupied molecular orbital (HOMO) - the lowest unoccupied molecular orbital (LUMO) and a higher light harvesting, oscillator strength and red shift in the absorption spectra. These changes facilitate the charge transfer phenomena in the nano structure of the chlorophyll as dye and improve the solar cell efficiency. (paper)