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

All inorganic Cs PbBrperovskite quantum dots(QDs) have been recognized as promising optical materials tfabricate green light emission devices because of their excellent optical performance. However, regular Cs Pb BrQDs with an oleic acid(OA) ligand show poor stability, which limits their practical application. We replaced thOA ligand in Cs PbBrQDs with a 2-hexyldecanoic acid(DA) ligand and, in the synthesis, found that the nematerial has better optical properties than regular Cs PbBrQDs(Cs PbBr-OA QDs). Due to the strong bindinenergy between the DA ligand and QDs, the ligand-modified Cs PbBrQDs(Cs PbBr-DA QDs) show a higphotoluminescence quantum yield(PLQY) of 96%, while the PLQY of Cs PbBr-OA QDs is 84%. Subsequentlythe Cs PbBrQDs coated on the blue light-emitting diode(LED) chips as green phosphors are demonstrated. Thcolor conversion from blue to pure green is achieved by adding the Cs PbBr-OA QDs solution up to 60 μL, whilthe pure green emission devices only need 18 μL Cs PbBr-DA QDs solution under the same concentration. Thultrapure, highly efficient green light-emitting devices based on Cs PbBr-DA QDs exhibit a luminous efficiencof 43.6 lm/W with a CIE(0.2086, 0.7635) under a 15.3 m A driving current. In addition, the green emissiowavelength of the devices based on Cs PbBr-DA QDs almost has no shift, even under a high injection currenThese results highlight the promise of DA ligand-modified Cs PbBrQDs for light-emitting devices and enrich thapplication field of ligand-modified Cs PbBrQDs.