Theoretical studies of electronic and optical characteristics in donor-π-Acceptor (D-π-A) dyes: DFT and TD-DFT methods

Abstract

Abstract This research focused on enhancing D-π-A organic dyes derived from coumarin and its derivatives, collectively referred to as D-CM-A dyes. The study aimed to improve these dyes by introducing various donors and acceptors to the coumarin structure. Six new coumarin dyes were evaluated, primarily for their potential application in dye-sensitized solar cells (DSSCs) to enhance energy efficiency. The analysis involved calculating the geometry, electronic properties, and optoelectronic characteristics of the dye molecules using DFT and TD-DFT methods with the B3LYP functional and the 6-311G basis set in both gas and solvent phases. The primary focus was to understand how modifications to the π-conjugated D-π-A organic dyes influenced their optoelectronic properties, including key factors such as maximum absorption wavelength (λmax), highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), and energy gap (Egap). Additionally, the study explored the photovoltaic properties of these dyes. The findings highlighted D4-CM-A4 as a promising candidate with the narrowest energy gap, while D1-CM-A1 and D2-CM-A2 showed superior light-harvesting efficiencies (LHE) compared to other derivatives. In conclusion, this study suggests that D1-CM-A1 and D2-CM-A2 are favourable choices for enhancing the performance of DSSCs due to their promising optoelectronic properties.