Design and analysis of novel D-π-A configuration dyes for dye-sensitized solar cells: a density functional theory study

This study explores the electronic, optical, and electrochemical properties of novel D-pi-A organic dyes with different pi-bridges using DFT and TD-DFT calculations, emphasizing their potential as efficient light harvesters. Geometric analysis shows that the dyes' bond lengths and dihedral angles support intramolecular charge transfer, light absorption, and stability. The pi-bridge improves electronic coupling, promoting conjugation and electron mobility. Frontier molecular orbital analysis reveals HOMO and LUMO levels aligned with TiO2 conduction band and the electrolyte's redox potential, ensuring efficient electron injection and dye regeneration. The dyes' energy gaps (2.1151-2.5426 eV) enable effective visible-light absorption. Molecular orbital distribution supports charge separation for efficient donor-to-acceptor electron transfer. Global reactivity parameters indicate high stability and enhanced charge transfer capabilities. Molecular electrostatic potential and reduced density gradient analyses highlight charge distribution and non-covalent interactions that improve stability and electronic properties. UV-Vis spectra (543.021-624.762 nm) reveal enhanced light-harvesting efficiency via n -> pi* transitions enabled by the pi-bridge. Electrochemical parameters, including oxidation potential and free energy changes, confirm their suitability for DSSCs. These dyes demonstrate significant potential for renewable energy applications, particularly in DSSCs.