Computational design of D-π-A dyes for improved photovoltaic performance: a DFT approach

The study focuses on producing new compounds using a balanced design system by enhancing dye characteristics through chemical modification. The D-π-A formation systems with modified π-bridges were employed, where the acceptor is 3,5-dimethyl-2-thioxo-2l5,3l4,4l5-thiazol-4-one with carboxyl groups promoting adsorption and electron injection, and the donor is tri-p-tolylamine. The properties of the newly designed dyes, including structure, geometric properties, frontier molecular orbitals, chemical reactivity indices, molecular electrostatic potential surface, gradient and Laplacian of electron density, UV–Vis absorption spectra, effectiveness as a photon harvester, and electrochemical properties, were reported and analyzed using density functional theory (DFT) and its time-dependent DFT. These properties indicate potential optical and photonic applications for the dyes. The designed D-π-A system dyes can be utilized as dye sensitizers in dye-sensitized solar cells (DSSCs), facilitating electron injection from the excited dyes to the conduction band of the acceptor (TiO2) and promoting stability through delocalization and intramolecular charge transfer. The introduced bridges in the molecular systems enable effective electron transfer from the donor to the acceptor. The observed excitations confirm successful electron injection from the excited designed dye systems to the semiconductor (TiO₂). This theoretical investigation provides strategies for synthesizing efficient D-π-A system materials for DSSCs, with the new dyes functioning as effective photosensitizers for DSSCs applications.