Synergetic Effect of Postsynthetic Water Treatment on the Enhanced Photoluminescence and Stability of CsPbX3 (X = Cl, Br, I) Perovskite Nanocrystals

All inorganic cesium lead halide CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs) are generally considered to be sensitive and even decompose when exposed to ambient humidity. Herein, we perform a well-controlled investigation of the effect of postsynthetic water treatment of the as-prepared CsPbX3 NCs on the photoluminescence quantum yields (PLQYs) and stability, and one can find that the surface defective layer of CsPbX3 NCs can be dissolved into water and we can further separate the supernatant CsPbX3 NCs hexane solution from the water, which improves the PLQYs of CsPbCl3, CsPbBr3, CsPbI3 from 5%, 69.3%, 68.1% to 78.5%, 95.5%, 91%, respectively. As a synergetic effect, a trace amount of residual water facilitated the hydrolysis of tetramethyl orthosilicate, leading to the formation of SiO2-coated CsPbX3 NCs with high stability. The stable green-emitting CsPbBr3/SiO2 composite is used as an example to combine with red K2SiF6:Mn4+ to fabricate the light-emitting diodes device on the blue InGaN chip, which displays wide color gamut (128% of National Television Standard Committee standard), providing the possibility for liquid-crystal display backlight utilization.