Advancing optoelectronic performance of organic and perovskite photovoltaics: computational modeling of hole transport material based on end-capped dibenzocarbazole molecules

Six novel carbazole-based hole-transporting materials (HTMs) (DBC1–DBC6) have been meticulously engineered through structural modifications of the reference molecule R. These tailored molecules were designed by introducing thiophene-bridged and end-capped acceptor groups. A comprehensive analysis of critical characteristics, including frontier molecular orbitals (FMO), density of states (DOS), dipole moment (µ), optical properties, reorganization energy of holes and electrons (λ_h, λ_e) , open-circuit voltage ( V_oc ), and fill factor (FF), was conducted using DFT and TD-DFT methods to assess their photovoltaic potential. Comparing the energy levels of the reference and designed molecules reveals their suitability as efficient hole transport materials for application in perovskite solar cells (PSCs). These engineered molecules have a lower-energy HOMO, a reduced energy gap (from 2.99 to 2.02 eV), and this change is associated with an improvement in hole mobility. All newly molecules (DBC1–DBC6) manifest higher absorption maxima ( λ_max ) in the solvent (dichloromethane), up to 524 nm, surpassing the reference R (408 nm). This signifies superior light absorption properties and efficient hole transfer in the designed molecules. Furthermore, the hole reorganization energy λ_h (from 0.112 to 0.850 eV) demonstrates improved hole mobility and reduced recombination losses compared to the R molecule. The designed HTMs exhibit substantial improvements in terms of energy conversion efficiency PCE (from 26.83 to 30.53