Density functional theory/time-dependent density functional theory study of electron-accepting groups on Hagfeldt-donor-based dye sensitizers for solar cells

Abstract Dye-sensitized solar cells are particularly promising candidates for sustainable energy because of their cost-effectiveness and tunable photophysical properties. This study employs density functional theory and time-dependent density functional theory methodologies to systematically optimize Hagfeldt-donor-based sensitizers through structural modulation of A1-site auxiliary acceptors and A2-site anchors. A comparative analysis was conducted between the PBE0/TD-cam-B3LYP protocol and experimental benchmarks, with the objective of ascertaining the most accurate framework for this particular dye class. The findings of this analysis revealed that the PBE0/TD-cam-B3LYP protocol exhibited a minimal deviation of 3 nm, thereby substantiating its preeminence in accuracy. Excitation and photophysical analyses demonstrate that the integration of benzothiadiazole derivatives and dithiocarboxyl (−CSSH) groups has the potential to significantly broaden the spectral response into the near-infrared region and enhance molar absorptivity. A thorough evaluation of the frontier molecular orbitals and predicted photovoltaic parameters revealed HJ36, HJ37, HJ39 and HJ44 as promising candidates, which exhibited high extinction coefficients up to 12.13 × 104 M−1 cm−1 and near-unity light-harvesting efficiency, and predicted power conversion efficiencies comparable to or exceeding those of the reference dye XY1. The study determined that efficiency indicators function as computational predictions based on theoretical experiments, serving to guide future laboratory synthesis.