Super-Hydrophobic Cesium Lead Halide Perovskite Quantum Dot-Polymer Composites with High Stability and Luminescent Efficiency for Wide Color Gamut White Light-Emitting Diodes

We present a novel composite strategy to enhance the stability of water-sensitive CsPbBr ₃ quantum dots (QDs) by embedding the QDs into the super-hydrophobic porous organic polymer frameworks (CPB@SHFW). The CPB@SHFW composites not only preserve a high photoluminescence quantum yield (PLQY ≈ 60%) and narrow band emission (full width at half-maximum ≈ 16 nm) but also inherit the outstanding water-resistant property of SHFW to protect the QDs from hydrolytic degradation. The PLQY of the composites was maintained at 91% (PLQY ≈ 54.3%) of the initial one (PLQY ≈ 60%) after being immersed in water for 31 days. Even after being immersed in water for 6 months, the CPB@SHFW composites still retain a bright green emission. In addition, super-hydrophobic perovskite QD-polymer composites (IPQDs@SHFW) with tunable and bright emission were prepared by using suitable halide salts. A white light-emitting diode (WLED) device was prepared by combining green-emitting CPB@SHFW composites and red-emitting K ₂ SiF ₆ :Mn ⁴⁺ phosphors with a blue LED chip. The device exhibits a high luminous efficiency of 50 lm/W and a wide color gamut (127% of the National Television System Committee and 95% Rec. 2020). This work provides an alternative approach to solve the challenging stability issue of perovskite QDs; therefore, it has a positive implication for their practical application in liquid crystal display backlights.