Alkylsilyl-substituted benzodithiophene-based small molecules as promising hole-transport materials for perovskite solar cells

Abstract

Organic semiconductor small molecules have gained significant attention as interfacial hole-transport materials (HTMs) for application in perovskite solar cells (PSCs). Herein, we report the investigation of three donor–acceptor small molecules consisting of benzodithiophene, benzothiadiazole, and thiophene moieties as HTMs. The morphology, charge mobility, and charge extraction ability of the developed molecules are shown to strongly depend on the shape and number of alkylsilyl side groups. The optimized PSCs with HTM TB-Si_3-3 comprising four peripheral (i-Pr)₃Si-groups delivered the best power conversion efficiency of 16.8%. The results obtained suggest the great potential of alkylsilyl-substituted small molecules as dopant-free HTMs for perovskite photovoltaic applications.