Highly efficient emission and high-CRI warm white light-emitting diodes from ligand-modified CsPbBr<sub>3</sub> quantum dots

All-inorganic CsPbBr₃ perovskite quantum dots (QDs) have received great attention in white light emission because of their outstanding properties. However, their practical application is hindered by poor stability. Herein, we propose a simple strategy to synthesize excellent stability and efficient emission of CsPbBr₃ QDs by using 2-hexyldecanoic acid (DA) as a ligand to replace the regular oleic acid (OA) ligand. Thanks to the strong binding energy between DA ligand and QDs, the modified QDs not only show a high photoluminescence quantum yield (PLQY) of 96% but also exhibit high stability against ethanol and water. Thereby warm white light-emitting diodes (WLEDs) are constructed by combining ligand modified CsPbBr₃ QDs with red AgInZnS QDs on blue emitting InGaN chips, exhibiting a color rendering index of 93, a power efficiency of 64.8 lm/W, a CIE coordinate of (0.44, 0.42) and correlated color temperature value of 3018 K. In addition, WLEDs based on ligand modified CsPbBr₃ QDs also exhibit better thermal performance than that of WLEDs based on the regular CsPbBr₃ QDs. The combination of improved efficiency and better thermal stability with high color quality indicates that the modified CsPbBr₃ QDs are ideal for WLEDs application.