Selective Peeling for Patterning on Layer-by-Layer Converted Perovskite–PbI₂ Heterostructure Film

With the rapid development of metal halide perovskites and their optoelectronics, a material-friendly and cost-effective patterning technique, typically through a top-down approach, is highly demanded to satisfy the requirements of device miniaturization and array formation. Here, a selective peeling methodology has been developed to pattern the high-quality perovskite film obtained via vapor-phase conversion in organic halide vapor of wafer-scale monocrystalline PbI₂ epitaxially grown on muscovite. Owing to the layer-by-layer conversion of PbI₂, a perovskite-PbI₂ vertical heterostructure film has been achieved. Leveraging the easily peeling characteristic of layered PbI₂, a prepatterned PDMS stamper with designed geometries was applied to the heterostructure film, selectively peeling the underlying PbI₂ sheets in the contact region and realizing precise patterning of the top MAPbI₃ layer at room temperature without additional treatments. Photodetector arrays have been integrated by the lamination of Au electrode pairs, with dark current suppressed by both the energy band alignment of the MAPbI₃-PbI₂ heterostructure and the isolation of mesas by the selective peeling approach; meanwhile, the photocurrent has been maintained, rendering improved detectivity of 2.7 × 10¹¹ Jones. This approach enables efficient production of perovskite arrays, facilitating broader applications in perovskite electronics and optoelectronics.