Design of new thiophene-based hole transport materials for high-efficiency perovskite solar cells: A DFT study and...

Thiophene-based hole-transporting materials have attracted a great deal of interest recently due to their improved performance. To explore the impact of substituting diphenylamine with triphenylamine, as well as introducing thiophene derivatives, on the optoelectronic properties of hole-transport materials for perovskite solar cells (PSCs), four new molecules (TFBT, TF1, TF2, and TF3) were designed using DFT and TD-DFT methods. The results show that all the designed molecules display a lower band gap (2.82 eV to 3.40 eV) compared to the reference molecule (3.63 eV), indicating enhanced electron density transfer. Additionally, TFBT, TF1-TF3 presented a greater λ_max ranging from 384 nm to 421 nm in dimethylformamide solvent, as compared to reference molecule (380.61 nm). All the designed molecules have a hole reorganization energy lower than that of the electron reorganization energy, indicating that the new HTMs exhibit a higher mobility of holes than electrons. The designed HTMs exhibited significant improvements in terms of open-circuit voltage (1.01 V - 1.08 V) and fill factor (0.8837-0.8895). On the other hand, Monte Carlo simulation indicates that the newly designed HTMs adsorb efficiently on the MAPbI₃ (110) surface, generating strong interactions that promote charge transfer. These results demonstrate that all four novel small molecules are promising candidates for perovskite solar cells (PSCs).