Fig. 1: Large-size single-crystalline PbI2 grown at the water-air interface.
a Schematic illustration of the crystal structure and the preparation, growth, and recycle process of 2D layered PbI2. The red arrows on the water surface indicate the horizontal accumulation of I− and the red arrows in the water indicate the attraction of I− to Pb2+. b Optical images of PbI2 when using the backside of Si/SiO2 as a substrate, with focal plane on water surface or substrate surface before and (c) after water evaporation. d Transmission electron microscopy and (e) scanning transmission electron microscopy images of a large-size PbI2 nanosheet obtained through water-air interfacial growth. The inset displays superimposed diffraction patterns captured at various regions of the nanosheet, denoted by different-colored dots, all of which closely coincide with each other, indicating the single crystalline structure of our-grown PbI2. f Micro-Raman (blue lines) and photoluminescence (red line) spectra of PbI2 at room temperature.
