High-Performance Perovskite Solar Cells by One-Step Self-Assembled Perovskite-Polymer Thin Films

Perovskite materials have drawn the greatest attention as alternatives for approaching cost-effective perovskite solar cells (PSCs) in the past decade. However, the desire for PSCs with photocurrent hysteresis-free characteristics has been unfulfilled due to the intrinsic foibles of perovskite materials. In this study, PSCs with boosted power conversion efficiency (PCEs), dramatically suppressed photocurrent hysteresis, and significantly boosted stability through one-step self-assembled methylammonium lead iodide (CH3NH3PbI3) cocrystallized with poly(ethylene oxide) (PEO) are reported. It is found that one-step self-assembled CH3NH3PbI3 cocrystallized with PEO could generate high-quality thin film with significantly enlarged crystal grains through weak hydrogen interactions between CH3NH3PbI3 and PEO. Further studies demonstrate that one-step self-assembled PEO–CH3NH3PbI3 thin films possess improved charge carrier transport, reduced charge carrier recombination, and promoted charge carrier extraction time as compared with those of one-step self-assembled processed CH3NH3PbI3 thin film. As a result, PSCs by one-step self-assembled PEO–CH3NH3PbI3 thin films exhibit a PCE of 20.78%, which is an over 20% enhancement compared to that (17.42%) from PSCs by one-step self-assembled CH3NH3PbI3 thin films. Moreover, PSCs by one-step self-assembled PEO–CH3NH3PbI3 thin films exhibit dramatically suppressed photocurrent hysteresis and significantly boosted stability. All these results demonstrate that the method of one-step self-assembled perovskites cocrystallized with polymers is a facile approach toward high-performance PSCs.