Controllable Synthesis of Metal Halide Perovskites Nano Arrays: Structure, Optical Properties, and Cathodoluminescence

Perovskites are conventionally represented by a general empirical formula ABX₃, containing a large family of materials. Along with their leading potential applications in opto-electronics and photovoltaics, perovskites hold the promise in the area of photodetection by converting stimuli into optical/electrical signals. Lead halide perovskite nanocrystals have shown remarkable properties for emission applications in the metal-metal halide family. Herein, we report a room-temperature-based synthesis of colloidal (i) CsPbI₃ prepared in N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO); (ii) carboxylic group oleic acid ligand-assisted synthesis of CsPbI₃; and (iii) hydrothermal synthesis in DMF/DMSO and oleic acid. These nano colloids have uniform sizes less than 50 nm in diameter, supported by powder X-ray diffraction and transmission electron microscopy. These nano colloids show optical properties, including composition-tunable emission spectra over a spectral region of 400–620 nm, with a stoke-shift of 30 nm, depending upon the synthesis methods, and hence crystal phases and size distributions. The crystal phases were tuned from tetragonal to orthorhombic to cubic, when solvent and temperature were changed. Further, pre-mixed solutions of the above three methods were used in anode aluminum oxide (AAO) templates to prepare 1D nanowires of various diametric sizes ranging from 20 nm to 200 nm under vacuum. These prepared nanowires were compared with the previous methods.  The aligned nanowires in AAO are designed to enhance the detection performance of a CsPbI₃ detector for ionizing radiation detections.