ZnSeTe/CdZnSe-based type-II core–shell quantum dots with tunable blue emission

Blue emissive quantum dots are key materials in emerging light-emitting technologies for display applications. Herein, we report the synthesis of ZnSeTe/CdZnSe-based type-II core–shell quantum dots with a low Cd content of less than 2.5%. By modifying the Cd content of the CdZnSe shell, photoluminescence emission can be tuned from 430 to 510 nm with a full width at half maximum of less than 26 nm. Transient absorption spectra illustrate the charge transfer between the conduction band of ZnSeTe and the conduction band of CdZnSe, as well as the recombination between the valence band of ZnSeTe and the conduction band of CdZnSe. By subsequent growth of ZnSe and ZnS shells, the resulting quantum dots achieved a photoluminescence quantum yield of 95%. We further demonstrate a blue quantum dot light-emitting diode with an emission peak at 467 nm, showing a maximum external quantum efficiency of 5%, a maximum luminance of 10,376 cd·m⁻², and an extrapolated T₉₅ lifetime of 4.7 h.