Enhanced Light Absorption and High Stability of Perovskite Microcrystals in Manufacturing Photovoltaic Devices by Antisolvent-Assisted Inverse Temperature In Situ Crystallization

Perovskite solar cells (PSCs), as a kind of next-generation renewable resource, have drawn tremendous research attention, accompanied by the rocketing power conversion efficiency (PCE) progress. However, the polycrystal films based on a traditional coordinative solvent procedure release a high density of defects or impurities, severely challenging the solar utilization efficiency and long-term stabilities of materials and devices. Here, a crystallization path of antisolvent-assisted reverse temperature crystallization was first developed for thin-layered structures. High-quality MAPbI₃ microcrystals were first rapidly precipitated in the mixture of a γ-valerolactone solvent and an anisole antisolvent at a lowered temperature of 70 °C, which showed excellent stability for over 3000 h under both ambient and thermal treatment. The MAPbI₃ films were subsequently prepared by similar in situ antisolvent-assisted reverse temperature crystallization during spin-coating, before which redissolving the as-obtained microcrystals was indispensable. Relative PSC devices presented a moderate PCE of 18.47% and retained 79.3% of their initial PCE after 300 h in air with an extreme relative humidity of 80–90%. This work provides a potential routine to prepare intrinsically stable microcrystal perovskites for PSCs and especially succeeded in the compatibility of the inverse temperature crystallization path with thin-film shaping as well as the eco-friendly and time-saving advantages.