Quantum design and investigation of dibenzo[g,p]chrysene-based hole transport materials for efficient perovskite solar cells

This study presents a series of novel hole-transporting materials (HTMs) based on a double helicene, dibenzo[g,p]chrysene (DBC) core, featuring side-arm diphenylamine (DPA) units, designed for perovskite solar cells (PSCs). For this, five new HTMs (DBC1-DBC5) were successfully designed by incorporating end-stage acceptor units via a thiophene spacer. The quantum calculations were performed using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) at 6-31G (d,p) basis set to scrutinize the tailored HTMs. The results confirmed that DBC1-DBC5 have more stabilized HOMO energies (−5.24 eV to −4.69 eV), narrower energy gap (1.92 eV to 2.22 eV), and high absorption coefficient (534–645 nm in solvent) compared to model molecules DBC-OMeDPA and state-of-the-art Spiro-OMeTAD. Moreover, excitation analysis of DBC1-DBC5 revealed that these materials have low charge coupling, stronger exciton dissociation, and high intrinsic charge transfer (up to 88 %), and minimal exciton binding energies (0.26 to 0.30 eV), facilitating efficient charge separation. While designed materials exhibit electron reorganization energies lower than their hole counterparts, their HOMO-LUMO energy alignment strongly supports hole transport behavior, as the LUMO levels are too high to accept electrons from the perovskite conduction band. Additionally, their smaller hole reorganization energies (0.1281 to 0.2147 eV) when compared to Spiro-OMeTAD suggest robust hole mobility, attributed to the optimized core functionality. This comprehensive study provides valuable insights into HTMs for PSCs. Overall, this study highlights the vital role of DBC-based HTMs in advancing PSC technology through superior charge dynamics and optimized energy levels.