Polar-Solvent-Free Synthesis of Highly Photoluminescent and Stable CsPbBr₃ Nanocrystals with Controlled Shape and Size by Ultrasonication

In this work, we report a polar-solvent-free, low-cost, and environmentally friendly method for synthesizing highly stable all-inorganic CsPbBr3 nanocrystals (NCs). Their shape and size are controlled by adjusting key parameters in the synthesis, such as capping ligands as well as ultrasound power and radiation time. The CsPbBr3 NCs are tunable from three-dimensional to two-dimensional and finally to 0-dimensional, by controlling the ratios and types of capping ligands. The CsPbBr3 NCs exhibit optical properties dependent on their shape and size, with photoluminescence quantum yield as high as 83%. Moreover, the role of nonpolar solvents in improving the stability of the CsPbBr3 NCs and the mechanism for the tunable growth of CsPbBr3 NCs are studied and discussed. Controlled shape and size of perovskite NCs are desired for applications, including solar cells, lasers, light-emitting diodes, and solar concentrators