Thin-shell CdSe/ZnCdS core/shell quantum dots and their electroluminescent device application

Abstract

To reduce the charge injection barrier, we attempt to synthesize thin-shell CdSe/Zn_xCd_1−xS core/shell quantum dots (QDs) in this work. A low-temperature (90–115 °C) synthetic scheme was developed for highly luminescent CdSe/Zn_xCd_1−xS core/shell QDs by employing short-chain tert-dodecanethiol as the ligand and low-boiling xylene or octane as the solvent. Thiol-capped CdSe/2Zn_xCd_1−xS core/shell QDs with two monolayers of the shells were directly synthesized in open air, including CdSe/2ZnS, CdSe/2Zn_2/3Cd_1/3S, CdSe/2Zn_1/2Cd_1/2S, CdSe/2Zn_1/3Cd_2/3S, CdSe/2CdS, and CdSe/1CdS/1ZnS core/shell QDs. These short-chain ligand capped and thin-shell QDs were used as the emitting layers to fabricate quantum dot light emitting diodes (QD-LEDs). The results showed that QDs coated with an alloyed Zn_0.5Cd_0.5S shell possess the optimal photoluminescence (PL) and electroluminescence (EL) properties as well as a maximum current efficiency of 12.5 cd A⁻¹.