DFT and TD-DFT Studies of D-π-A Organic Dye Molecules with Different Spacers for highly Efficient Reliable Dye Sensitized Solar Cells.

Abstract

This study focuses on six D-π-A systems, utilizing diverse π-spacers as bridges. Comprehensive analysis through Density Functional Theory (DFT) and Time-dependent Functional Theory (TD-DFT) methods at B3LYP using 6-31G (d.p) basis set explores geometrical, electrical, optical, photovoltaic, and absorption properties. EHOMO, ELUMO, and energy gap (Egap), for all of these dyes have been determined and discussed using ground state optimization. TD-DFT calculates optical properties, unveiling enhanced excitation energies and HOMO-LUMO energy levels, indicative of improved electron injection and dye regeneration processes. Examination of energy gap, open-circuit voltage (VOC), free energy change (ΔGinject), light harvesting efficiency (LHE), and absorption spectra reveals D4 dye's lower Egap and robust absorption in the visible spectrum. Molecular tailoring emerges as a promising technique for optimizing D-π-A sensitizer design, offering potential advancements in DSSCs applications.