Management of the π-Conjugated System in Carbazole–Diphenylamine Derivative-Based Hole-Transporting Materials for Perovskite Solar Cells: Theoretical Simulation and Experimental Research

Abstract

Molecular design of hole transport materials (HTMs) is an important approach to improving the performance of perovskite solar cells (PSCs). In this work, starting from carbazole−diphenylamine derivatives, three HTMs, CY3−CY5, are designed to modulate the performance of HTMs by means of the introduction of different conjugation groups on the side chains. The theoretical simulation results indicate that the designed HTMs CY3−CY5 exhibit stable molecular structures, suitable frontier molecular orbital energy levels, and negative solvation free energies. Compared with CY3 and CY4, CY5 exhibits higher hole mobility due to its stronger orbital coupling. At the same time, CY5 in PSC applications can yield a stronger interfacial adsorption on the perovskite film. The experimental results provide important conditions for verifying the reliability of the theoretical model. Therefore, the optimized PSC devices based on CY5 achieve a significant power conversion efficiency (22.01%), which is better than the PSCs based on CY3 (21.28%) and CY4 (19.62%) under the same conditions. By combining theoretical calculations and experimental exploration, the feasibility of obtaining potential HTMs by means of π-conjugate extension to modulate the intermolecular orbital coupling and the interaction on the perovskite surface to improve the efficiency of PSCs are confirmed.