Regulation of Intermolecular and Interfacial Interactions by Functionalization of Substituent Groups in Hole Transport Materials for Perovskite Solar Cells: A Density Functional Theory and Experimental Study

Developing potential hole transport materials (HTMs) is an effective approach to reduce carrier nonradiative recombination and improve the efficiency of perovskite solar cells (PSCs). To investigate the intermolecular and interfacial interactions of HTMs in PSC devices, two molecules (RQ7 and RQ8) with substituent group functionalization are designed by isomerizing ‐F and ‐SMe in the para‐ and ortho‐positions on the side chain of carbazole diphenylamine‐based HTMs. Theoretical simulations indicate that the functionalization of substituent groups in HTMs alters their dipole moments and electronic structures, as well as their intermolecular interactions, hole transport capabilities, and interfacial interactions at the HTMs/perovskite interface. Experimental results show that RQ8 exhibited higher hole mobility, better film‐forming ability, and reduced electron‐hole recombination, resulting in RQ8‐based PSC devices achieving a higher power conversion efficiency than those based on RQ7. Herein, it is demonstrated that isomerous functionalization of substituent groups in carbazole diphenylamine‐based HTMs is a feasible strategy for controlling and regulating the intermolecular and interfacial interactions of HTMs in PSC applications.