Theoretical end-cap tailoring of tripodal triazatruxene-based hole transport materials toward enhanced perovskite solar cell performance.

This study reports the design and computational evaluation of five tripodal triazatruxene-based hole-transporting materials (HTMs), M1-M5, derived by integrating a tripodal-triazatruxene scaffold with five different terminal acceptors. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations revealed absorption maxima in the range of 547-793 nm in dichloromethane (DCM), indicating strong near-visible light absorption. The designed HTMs exhibited HOMO energy levels between -5.51 and -3.16 eV and reduced band gaps of 2.22-2.70 eV relative to the parent molecule. Hole reorganization energies (0.07-0.24 eV) were generally lower than electron reorganization energies (0.06-0.30 eV), supporting favorable hole-transport characteristics. The charge transfer integrals for holes ranged from 0.01 to 0.05 eV, while the calculated open-circuit voltage and fill factor reached 1.10-1.66 V and 89.1%-92.1%, respectively. The designed molecules also demonstrated significantly enhanced power conversion efficiencies (29.62%-36.69%) compared with the parent compound (23.52%). These results identify M1-M5 as promising HTM candidates for high-performance solar energy applications.