Preparation of High-Performance Inorganic Perovskite Solar Cells through In Situ Ion-Exchange-Controlled...

Enhancing film quality and passivating defects are effective strategies for improving the power conversion efficiency (PCE) and the open-circuit voltage (V_OC) of inorganic perovskite solar cells (IPSCs). In this study, an in situ ion exchange (ISIE) approach was put forward to synthesize dimethylammonium acetate (DMAAc) and lead iodide (PbI₂), which controls crystallization and passivates defects. The reaction between lead acetate (Pb(Ac)₂) and dimethylammonium iodide (DMAI) occurs spontaneously, yielding PbI₂ and DMAAc. Therefore, this additional reaction establishes a minor competitive relationship during the crystallization process, thereby enhancing crystal growth by slowing the rate of crystallization. Furthermore, both PbI₂ and DMAAc serve to passivate defects and improve film quality, respectively. The nonradiative recombination is minimized, and the configuration of energy levels is optimized. As a result, the champion PCE of inverted IPSCs fabricated in air reaches 21.23%. This represents one of the highest PCE values currently recorded among IPSCs.