Orientation-Controlled Large-Area Epitaxial PbI Thin Films with Tunable Optical Properties.

Lead iodide (PbI) as a layered material has emerged as an excellent candidate for optoelectronics in the visible and ultraviolet regime. Micrometer-sized flakes synthesized by mechanical exfoliation from bulk crystals or by physical vapor deposition have shown a plethora of applications from low-threshold lasing at room temperature to high-performance photodetectors with large responsivity and faster response. However, large-area centimeter-sized growth of epitaxial thin films of PbI with well-controlled orientation has been challenging.