Impact of Molecular Side‐Chain Modifications on Triphenylamine‐Based Materials as Donors for Organic and as Hole Transporting Materials for Perovskite Solar Cells

Triphenylamine‐based hole‐transporting materials are widely used in perovskite solar cells (PSCs) due to their high‐power conversion efficiency, low energy gap, and efficient charge transport. This study designs new materials by modifying biphenyl core‐based molecules at their terminal groups. Nine novel molecules (NS1‐NS9) are developed by replacing the OCH3 group in the reference molecule (NSR) with different electron‐accepting groups. Density functional theory (DFT) and time‐dependent DFT (TD‐DFT) at the B3LYP/6‐31G(d,p) level are used to analyze optoelectronic properties, energy levels, and charge transport characteristics to foresee their potential for PSCs. The modified molecules exhibit reduced highest occupied molecular orbital–lowest unoccupied molecular orbital energy gaps (0.64–1.25 eV) compared to reference NSR, and lower binding and reorganization energies, indicating enhanced charge transfer. To define the role of designed molecules as donors, these are blended with PC61BM, and an improved open‐circuit voltage is achieved. Compared to the reference NSR, the designed molecules (NS1‐NS9) showed better optoelectronic characteristics and photovoltaic performances. This shows the potential of these materials for the next‐generation organic and perovskite photovoltaics. Thus, these findings suggest that the newly designed molecules may significantly enhance the solar cell efficiency for real‐world and industrial applications.