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

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 degrees C and 50 +/- 5% relative humidity) and almost no degradation after 350 h under combined heat and light stressors (ISOS-L-2 standard). A macro-micro synergistic strategy to optimize the spreadability and reactivity of PbI2, which can accelerate the diffusion of an organic cation solution macroscopically and completely convert PbI2 into an optically active phase microscopically.