Two-Step Performance Optimization of CsPbBr₃ Perovskite Nanocrystals for Wide Color Gamut Displays

Owing to their composition-tunable and narrow emissions and high photoluminescence quantum yield (PLQY), inorganic halide perovskite quantum dots (IPQDs) are a promising option for wide color gamut displays. However, their practical applications have been limited by their lattice structure instability and surface defect states. Herein, CsPbBr3:KBF4@SiO2 with improved stability and optical properties is successfully synthesized with a two-step optimization of fluorine (F) anion doping and SiO2 in situ coating. Compared with bromide (Br), higher electronegativity and a smaller radius of F lead to stronger binding energy with Pb2+. Also, F anions can occupy surface Br vacancies. Then, benefiting from the acidic environment provided by BF4- hydrolysis, tetraethyl orthosilicate (TEOS) can be more easily hydrolyzed on the CsPbBr3:KBF4 surface to generate SiO2 coating, thus further passivating lattice defects and improving environmental stability. Importantly, the PLQY of CsPbBr3:KBF4@SiO2 achieves 85%, and the stability has been greatly improved compared with pure CsPbBr3. Finally, CsPbBr3:KBF4@SiO2/PDMS, CsPbI3/PDMS, and CsPbCl3/PDMS composites with narrow emissions are applied to replace traditional phosphors as color converters for direct-view light-emitting diode (LED) displays or liquid crystal display (LCD) backlights. The color gamut reaches 118.22% under the NTSC standard. Concerning the display field, it suggests likely applications in the future.