Synergistic Process Optimization and Surface Passivation for High-Performance Electrodeposited Perovskite Solar Cells

Electrodeposition provides a cost-effective, large-scale, highly reproducible, environmentally friendly, and flexible route for fabricating perovskite solar cells (PSCs), yet insufficient precursor conversion and severe interfacial defects greatly restrict electrodeposited PSCs' performance. Herein, we optimize two fabrication processes of HI spin-coating (HISC) and HI steep (HISP) and further apply octylammonium iodide (OAI) surface passivation to the superior HISP process (SPPE) to address these limitations. The HISP process produces more regular PbI2 precursor films with fewer impurities, promoting homogeneous grain growth with enhanced carrier lifetime. Consequently, the champion efficiency improves from 17.02% to 19.12%. Extending HISP with OAI passivation generates a dense two-dimensional perovskite layer that eliminates residual PbI2 and optimizes energy level alignment, reducing trap density, extending carrier lifetime, and boosting champion efficiency to 21.75%, while retaining 80% of its initial efficiency after 1392 h in a N2 atmosphere. This synergistic fabrication process optimization and OAI surface passivation enhance both efficiency and stability, providing insights for the development of high-performance electrodeposited PSCs.