Ultrapure and highly efficient green light emitting devices based on ligand-modified CsPbBr3 quantum dots

All inorganic CsPbBr3 perovskite quantum dots (QDs) have been recognized as promising optical materials to fabricate green light emission devices because of their excellent optical performance. However, regular CsPbBr3 QDs with an oleic acid (OA) ligand show poor stability, which limits their practical application. We replaced the OA ligand in CsPbBr3 QDs with a 2-hexyldecanoic acid (DA) ligand and, in the synthesis, found that the new material has better optical properties than regular CsPbBr3 QDs (CsPbBr3-OA QDs). Due to the strong binding energy between the DA ligand and QDs, the ligand-modified CsPbBr3 QDs (CsPbBr3-DA QDs) show a high photoluminescence quantum yield (PLQY) of 96%, while the PLQY of CsPbBr3-OA QDs is 84%. Subsequently, the CsPbBr3 QDs coated on the blue light-emitting diode (LED) chips as green phosphors are demonstrated. The color conversion from blue to pure green is achieved by adding the CsPbBr3-OA QDs solution up to 60 mu L, while the pure green emission devices only need 18 mu L CsPbBr3-DA QDs solution under the same concentration. The ultrapure, highly efficient green light-emitting devices based on CsPbBr3-DA QDs exhibit a luminous efficiency of 43.6 lm/W with a CIE (0.2086, 0.7635) under a 15.3 mA driving current. In addition, the green emission wavelength of the devices based on CsPbBr3-DA QDs almost has no shift, even under a high injection current. These results highlight the promise of DA ligand-modified CsPbBr3 QDs for light-emitting devices and enrich the application field of ligand-modified CsPbBr3 QDs. (c) 2020 Chinese Laser Press