The impact of azo -based modifications of D-ε ₃ -δ n -A (n = 1-3) and D-ε ₆ -δ n -A (n = 1-3) systems toward promoting dye-sensitized solar cells (DSSCs): DFT study

This study investigates the influence of azo moiety incorporation on the structural, electronic, optical, and photovoltaic properties of organic dyes employed in dye-sensitized solar cells (DSSCs) using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. We observed that incorporating azo groups significantly enhanced the strength of chemical bonds within the dyes, particularly in donor-π-bridge-acceptor (D-π-A) systems, resulting in notable changes in structural features. The electronic properties of the dyes revealed that azo moiety incorporation resulted in a narrowing of the energy gap (Egap), suggesting improved photon absorption capabilities. Also, the molecular orbital analysis indicated that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) distributions were altered, enhancing the dyes’ electron donation and acceptance potential. This study identified D-ε3-δ1-A-azo as a promising dye candidate, characterised by high chemical stability, optimal HOMO–LUMO alignment for electron transfer, and enhanced light-harvesting efficiency.