DFT and TD-DFT investigations of organic dye with different π-spacer used for solar cell

Abstract

The ground-state geometries and electronic properties of two D–π–A dyes (LEG4 and LEG4F) have been studied by using density functional theory (DFT) and time-dependent density functional theory. LEG4 and LEG4F have the same donor (triphenylamine) and acceptor (carboxylic acid) bridged by different π-spacer. We estimated the light harvesting efficiency, energy levels and electron density, electron accepting power, molar extinction coefficient, electron injection free energy, chemical hardness and reorganization energy. The results demonstrate that LEG4F has higher HOMO energy and lower energy gap, which is benefit to electron transfer. For configuration of LEG4F, it was found that it has a widen absorption spectra and larger maximum absorption strength, bigger light harvesting efficiency and improved electron injection ability in comparison with LEG4. The difference of photoelectric parameters for solar cell has been interpreted from the viewpoint of calculation, which is an important clue for understanding the relationship between structure and performance.