Single and Dual Doping of Blue-Emissive ZnSeTe Quantum Dots with Transition Metal Ions

Abstract

Doping particularly with transition metal ions is an effectual means to modulate photoluminescence (PL) of quantum dots (QDs). The precedent doped QDs rely primarily on single doping with either Cu+ or Mn2+ into the most common host compositions of (Zn)CdS, ZnSe, and InP, with little success on co-doping with both impurities enabling their simultaneous emissions. Herein, single and dual doping are explored with Cu+ and/or Mn2+ into blue-emissive ZnSeTe QDs. PL of the singly doped ZnSeTe QDs synthesized via a co-nucleation process, comprising host and dopant emissions, is spectrally tuned by varying the concentration of each dopant. For the effective dual doping toward co-emergence of both dopant-related emissions, a two-step doping strategy, where co-nucleation doping of Mn2+ is temporally decoupled from diffusion doping of Cu+, is devised. In the resulting co-doped ZnSeTe QDs, successfully showing three distinct emission components, the relative spectral distribution of triple emissions is readily modulated by individually adjusting Cu and Mn concentrations, producing color-quality tunable white emissions. Upon elaborate multishelling, the co-doped QDs display outstanding PL quantum yields of 72-75%. Singly and dually doped QDs are further applied for the fabrication of QD light-emitting diodes, and their electroluminescence is examined compared to PL.