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

All inorganic Cs PbBr3 perovskite 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 PbBr3 QDs with a 2-hexyldecanoic acid(DA)ligand and,in the synthesis,found that the nematerial has better optical properties than regular Cs PbBr3 QDs(Cs PbBr3-OA QDs).Due to the strong bindinenergy between the DA ligand and QDs,the ligand-modified Cs PbBr3 QDs(Cs PbBr3-DA QDs)show a higphotoluminescence quantum yield(PLQY)of 96%,while the PLQY of Cs PbBr3-OA QDs is 84%.Subsequentlythe Cs PbBr3 QDs 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 PbBr3-OA QDs solution up to 60μL,whilthe pure green emission devices only need 18μL Cs PbBr3-DA QDs solution under the same concentration.Thultrapure,highly efficient green light-emitting devices based on Cs PbBr3-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 PbBr3-DA QDs almost has no shift,even under a high injection currenThese results highlight the promise of DA ligand-modified Cs PbBr3 QDs for light-emitting devices and enrich thapplication field of ligand-modified Cs PbBr3 QDs.