Original Core–Shell Structure of Cubic CsPbBr₃@Amorphous CsPbBr_x Perovskite Quantum Dots with a High Blue Photoluminescence Quantum Yield of over 80%

All-inorganic perovskite cesium lead halide quantum dots (QDs) have been widely investigated as promising materials for optoelectronic application because of their outstanding photoluminescence (PL) properties and benefits from quantum effects. Although QDs with full-spectra visible emission have been synthesized for years, the PL quantum yield (PLQY) of pure blue-emitting QDs still stays at a low level, in contrast to their green- or red-emitting counterparts. Herein, we obtained core–shell structured cubic CsPbBr3@amorphous CsPbBrx (A-CsPbBrx) perovskite QDs via a facile hot injection method and centrifugation process. The core–shell structure QDs showed a record blue emission PLQY of 84%, which is much higher than that of blue-emitting cubic CsPbBr3 QDs and CsPbBrxCl3–x QDs. Furthermore, a blue-emitting QDs-assisted LED with bright pure blue emission was prepared and illustrated the core–shell QDs’ promising prospect in optoelectrical application.