Synthesis of Size-Controllable Self-Assembled CsPbBr₃ Perovskite Nanowires: Implications for Photoemission with Less Recombination

CsPbBr3 perovskite nanowires (NWs) with various lengths and widths have attracted much attention because of their attractive optoelectronic properties in optoelectronic devices. This study provides an effective approach to get size-controllable CsPbBr3 perovskite NWs based on the hot injection method. Oleylamine was used as the solvent to control the reaction speed, and CsPbBr3 perovskite NWs with adjustable widths and lengths were obtained by controlling the reaction time at 180 °C. X-ray diffraction, transmission electron microscopy (TEM), high-resolution transmission electronic microscopy, optical absorption, and photoluminescence (PL) spectra were carried out to investigate the structural evolution and growth mechanism. The results show that Cs4PbBr6 nanocrystals precipitated within 10 min and their amount reduced, and α-CsPbBr3 nanocrystals appeared and grew with the reaction time extending to 30 min. Cs4PbBr6 nanocrystals disappeared, and α-CsPbBr3 NWs with a width of ∼20 nm and a length of ∼1 μm were obtained when the reaction reached 60 min. Further extending the reaction time resulted in self-assembling and growth of CsPbBr3 NWs, the width of CsPbBr3 wires reached ∼1 μm, and the length reached ∼100 μm when the reaction time was 24 h. TEM images clearly showed that CsPbBr3 NWs become wider and longer by self-assembly of CsPbBr3 nanocubes and NWs. A statistics study revealed that there is a linear relationship between the width and the reciprocal of time. The self-assembly CsPbBr3 perovskite NWs presented a high-intensity green PL around 519 nm and high PL quantum yield, which was 71.7, 76.9, 64.9, and 39.5% for the samples reacted for 10, 30, 60, and 180 min, respectively, under 375 nm laser irradiation, and the photocarrier lifetime for the sample with 180 min can reach 25.79 ns. The obtained CsPbBr3 NWs have few defects and produce less recombination during the photoemission process, which is promising for applications in the fields of optoelectronic devices, especially photodetectors, lasers, and solar cells devices.