Simultaneous hole transport and defect passivation enabled by a dopant-free single polymer for efficient and stable perovskite solar cells†
Developing dopant-free hole transporting materials (HTMs) and passivating defects in perovskite films are two significant themes to realize efficient and stable perovskite solar cells (PSCs). Compared to various individual endeavors for either of them, enabling both via a single material is more interesting but certainly challenging. In this report, we develop dopant-free polymer HTMs bearing amino pendants as passivating groups for improved efficiency and stability of PSCs. The bifunctional polymers present simultaneous main-chain (donor–acceptor conjugated backbone) hole extraction/transport and side-chain (amino group) defect passivation at the perovskite/HTM interface. Moreover, with an increased content of amino pendants, the polymers exhibit enhanced hole mobility and defect passivation ability, advancing device efficiency and stability. As a result, PSCs using the dopant-free polymer HTM achieve an efficiency approaching 19%, with impressive stability when testing at a relative humidity of 85%, by heat at 80 °C, or under continuous light illumination. This work demonstrates that amino functionalization at the side chain of polymers is a promising method to develop dopant-free HTMs accompanied by defect passivation effects for high-performance and durable PSCs.