Effect of Electron-Withdrawing/-Donating Groups on the Sensitizing Action of the Novel Organic Dye 3-(5-(4-(Diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic Acid for N-Type Dye-Sensitized Solar Cells: A Theoretical Study

Computational studies using density functional theory and time-dependent DFT approaches have been performed to study a series of metal free donor-pi-linker-acceptor (D-pi-A) dyes. Taking the novel organic D5 dye (3-(5-(4-(diphenylamino)styryl) thiophen-2-yl)-2-cyanoacrylic acid) as the primary structure, with triphenylamine as the donor, cyanoacrylic acid as the acceptor, and a thiophene group as the pi-linker, we have studied the effect of the substitution of different electron-withdrawing and electron-donating groups at different positions on the dye efficiency, by analyzing the geometry, charge distribution, electron injection, and absorbance spectra. Electron injection has also been addressed for the substituted dyes immobilized on TiO2. Our calculations show that adding electron-withdrawing groups at specific positions will lead to a higher efficiency of the dye.