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In this work, the synthesis of regular single crystalline lead iodide nanoplatelets are carried out based on the physical vapor phase deposition method. Different lead iodide nanoplatelets are obtained by tuning the location of the mica substrate along with the temperature of the tube furnace. The rules of size, thickness, density of the lead iodide nanoplatelets at varied deposition conditions are analyzed according to the crystal growth principles. It was claimed in literature that the photoluminescence of lead iodide could be obtained only at a low temperature (lower than 200 K). Here, at room temperature, we successfully obtained the photoluminescence spectra of the prepared lead iodide nanoplatelets, which possess two apparent peaks due to the biexcitons and the inelastic scattering of excitons, respectively. Our present study contributes to the development of nanoscaled high performance optoelectronic devices.

The issue of organic-inorganic perovskites has received considerable attention because of its importance in improving the efficiency of solar cells. The power conversion efficiency of solar cells has climbed from 3.8% in 2009 to over 25.2% currently. Its outstanding performance is mainly attributed to its long carrier lifetime (101−2 ns), diffusion length (μm), high absorption coefficient, direct bandgap (band gap ~1.55 eV), stable electron/hole migration and other characteristics. In addition to these features, organic-inorganic lead perovskites also have high fluorescence yields and tunable absorption wavelengths, making it an ideal laser gain medium. In this paper, the physical vapor deposition (PVD) is used to grow atomically smooth lead iodide nanoplatelets (PbI2 NPL) on a mica substrate, and convert the PbI2 NPL into atomically smooth single-crystal perovskite nanoplatelets (CH3NH3PbI3 NPL) by chemical vapor deposition. The nanoplatelets can naturally form WGM (whispering-gallery-mode) microcavities. We can control the size of CH3NH3PbI3 NPL (from a few microns to dozens of microns) by adjusting the deposition location, deposition temperature, and deposition time. With the increase of edge length, the mode interval decreases, the peak is red shift, and it shows excellent lasing characteristics with a threshold down to 17 μJ/cm2. This has great application potential in the field of low-cost chip light source.