Macro–micro coordination optimization of lead iodide reactivity toward millimeter-to-centimeter-scale perovskite solar cells with minimal efficiency loss

Abstract

The sequential deposition process exhibits significant potential in the high-throughput production of cost-effective perovskite solar cells (PVSCs). However, the poor macroscopic scale spreading consistency and low microscopic scale conversion of lead iodide (PbI₂) would reduce the processing reproducibility and scalability of relevant large-scale PVSCs. Herein, a macro–micro synergistic strategy is introduced to optimize the spreadability and reactivity of PbI₂. Macroscopically, the preparation of a uniform nano-/micro-structured superspreading PbI₂ film could be conducive to accelerate the diffusion rate of an organic cation solution in the whole cross-section scale, thereby enhancing the homogeneity of the large-area perovskite film. Microscopically, the introduction of cosolvent Cyrene could produce highly reactive PbI₂ frameworks, which in turn promotes the conversion of PbI₂ to an optically active perovskite phase. Consequently, the resultant PVSC achieves a power conversion efficiency of 24.20% for a millimeter-scale device (active area of 0.04 cm²) and 23.13% for a centimeter-scale device (active area of 1.01 cm²) with a minimal efficiency loss of 4.4%. The unencapsulated centimeter-scale device retains 89% of its initial efficiency after 1008 h under AM 1.5G light soaking in air (25 ± 5 °C and 50 ± 5% relative humidity) and almost no degradation after 350 h under combined heat and light stressors (ISOS-L-2 standard).