Computational Analysis of Novel Broad-Absorption Donor–π–Acceptor Triphenylamine-Based Dye Molecules for High-Efficiency Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) are promising due to their cost-effectiveness, easy fabrication and performance under low light. This study designs and optimizes triphenylamine-modified molecules to improve DSSC photovoltaic and absorption properties. Six donor–[Formula: see text]–acceptor (D–[Formula: see text]–A) triphenylamine-based sensitizers (U1–U6) were modeled to broaden solar absorption. Derived from the reference dye D35, these compounds use end-capped acceptor engineering to enhance optical, electronic and charge transport properties. All designed derivatives (U1–U6) exhibited reduced band gaps (2.28–2.74 eV) compared to the reference dye [Formula: see text] (4.41 eV), resulting in an increased excitation dissociation rate. The absorption profiles studied in both the gaseous and solvent phases were in the range of 345–636 nm and 351–690 nm, respectively. The designed molecules also showed increased dipole moments (up to 14.69 D), lower reorganization energies and improved charge transport properties. Further noted that the absorption spectra of all the designed molecules were shifted towards longer wavelengths (red shifts). The NFA (Non fullerene Acceptors) substitution corresponds to a better sensitizer for DSSCs as they show the prominence in quantum mechanical properties and geometrical properties observed by the transition density matrix (TDM) and dipole moment analysis. The DSSCs photovoltaic parameters such as open circuit voltages ([Formula: see text] up to 1.28 V), fill factor (FF [Formula: see text]0.97) and quantum mechanical efficiency of solar cells were computed and subsequently were remarkably improved (power conversion efficiency (PCE) [Formula: see text] 22–27%, 40–70% higher) compared to reference molecule (PCE [Formula: see text] 15.94%). Current work demonstrates that quantum molecular modelling is an effective tool to design efficient and highly absorbent sensitizers for preparing more efficient high-performance DSSCs.