Evolution and Mechanism of Cesium Lead Bromide Nanostructures in Oleylamine-Rich System by Hot-Injection Method

Due to the ultrafast nucleation and growth rates of perovskite nanostructures during the synthesis, the products are difficult to control, such as its derivatives (e.g., Cs 4 PbBr 6 ) often appear. Here, the hot-injection method is ameliorated by using oleylamine (OAm) instead of octadecene as solvent. The results reveal that in OAm-rich system, the pure nanostructures with different Pb/Br ratios (CsBr, Cs 4 PbBr 6 , and CsPbBr 3 ) can be obtained at different reaction temperatures, and thus controlling the Pb-Br linkage and the interconnection of [PbBr 6 ] 4− octahedra, and resulting in the formation of different nanostructures. As the reaction temperature increases from 120 to 180 °C, the products change from lead-free CsBr nanocrystals to poor-lead Cs 4 PbBr 6 nanocrystals and finally to normal CsPbBr 3 nanocubes and nanowires. Moreover, the synthesized CsPbBr 3 nanowires exhibit an emission peak at 521 nm, full width at half maximum (FWHM) of 19 nm, with photoluminescence quantum yields (PLQY) of 64.9%, and high stability. Furthermore, the white light-emitting diode (WLED) devices are successfully fabricated based on the obtained CsPbBr 3 nanowires, showing high-intensity white light and high stability without any encapsulation. Remarkably, this work provides a new approach for elucidating the synthesis mechanism of perovskite nanomaterials and their applications.