Improving the efficiency and stability of perovskite solar cells through a multi-cycle methylammonium iodide spin coating approach assisted by the Ostwald ripening method

Abstract

In this study, we report a modified two-step deposition process for fabricating perovskite solar cells (PSCs), employing a multi-cycle spin-coating treatment of methylammonium iodide (MAI). This approach promotes the formation of the perovskite (PKT) phase through improved infiltration of MAI and grain growth driven by the Ostwald ripening process (ORP). As a result, enhanced crystallinity, improved surface morphology, and complete conversion of PbI₂ into the PKT phase were achieved. Furthermore, ORP-driven grain growth reduced grain boundary density and enhanced photovoltaic (PV) performance, achieving a power conversion efficiency as high as 8.85 %. In addition, the devices fabricated using the modified spin-coating method showed improved PV performance retention under ambient conditions with continuous illumination, demonstrating superior long-term operational stability. These results highlight the strong potential of the multi-cycle MAI spin-coating treatment to address key challenges in PSCs, contributing to the advancement of their commercialization.