Microencapsulated Perovskite Crystals via In Situ Permeation Growth from Polymer Microencapsulation-Expansion-Contraction Strategy: Advancing a Record Long-Term Stability beyond 10 000 h for Perovskite Solar Cells

Organic metal halide perovskite solar cells (PSCs) bearing both high efficiency and durability are predominantly challenged by inadequate crystallinity of perovskite. Herein, a polymer microencapsulation-expansion-contraction strategy is proposed for the first time to optimize the crystallization behavior of perovskite, typically by adeptly harnessing the swelling and deswelling characteristics of poly(4-acryloylmorpholine) (poly(4-AcM)) network on PbI 2 surface. It can effectively retard the crystallization rate of perovskite, permitting meliorative crystallinity featured by increased grain size from 0.74 to 1.32 µm and reduced trap density from 1.12 × 10 16 to 2.56 × 10 15 cm −3 . Moreover, profiting from the protection of poly(4-AcM) microencapsulation layer, the degradation of the perovskite is markedly suppressed. Resultant PSCs gain a robust power conversion efficiency (PCE) of 24.04%. Typically, they maintain 91% of their initial PCE for 13 008 h in a desiccated ambient environment and retain 92% PCE after storage for 4000 h with a relative humidity of 50 ± 10%, which is the state-of-the-art long-term stability among the reported contributions.