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.

Air-Stable and Environmentally Friendly Full Color-Emitting ZnSeTe/ZnSe/ZnS Quantum Dots for Display Applications

“…The ternary ZnSeTe alloy structures with intermediate band gaps of ZnSe and ZnTe may be practical alternatives for cadmium-free blue-emissive QDs around 460 nm. Additionally, by introducing a multishell heterostructure system such as core/shell/shell to ZnSeTe QDs, the surface defects can be effectively passivated, leading to a design of type I band structures with high PL QY. , These types of ZnSeTe semiconductor QDs recently demonstrated their potential by achieving very high PL QY and EQE. − However, the broader deployment of the well-known hydrofluoric acid (HF)-based synthesis of ZnSeTe/ZnSe/ZnS QDs could be hampered due to the presence of highly toxic HF in the synthesis. Since HF is a highly corrosive and toxic substance that can seriously harm bones and can cause blindness, excluding HF in the synthetic procedure is strongly desired.…”

Single-Phase Cu,Mn-Codoped ZnGaS/ZnS Quantum Dots for Full-Spectrum White-Light-Emitting Diodes

“…More excited electrons would be transferred to the luminescence centers of Mn 2+ ions, leading to an increase of the Mn-dopant emission and the quenching of the host and Cu-dopant emission . Mn-dopant emission showed a small red shift with an increase of the dopant concentration due to the enhanced probability of Mn–Mn interaction or Mn pair formation. , …”

“…The average decay times recorded at 450 and 500 nm were 0.845 and 1.714 μs, which are consistent with the lifetimes of host and Cu dopant emissions (Table S2). 21,40,47,48 Besides, the average decay time recorded at 580 nm was 4.209 ms, which corresponded with Mn d−d states. 24,26,43,49 As shown in Figure 3c, with an increase of the Zn/Ga molar ratio, the host emission showed an obvious blue shift.…”

“…However, the emission spectra of the codoped QDs are difficult to control and the PL QYs are usually low because various ions get involved in the synthetic process and the resulting surface-defect emissions are extremely sensitive to the surroundings. 39,40 The interaction mechanism and the realization of high PL QYs of transition-metal-ion-codoped ternary QDs are of great research value.…”

“…The emissions of doped QDs are strongly affected by the interaction between the host and dopants and/or the energy coupling of different dopants. − By changing dominant factors such as the dopant concentration and doping methods, the doped QDs will show single or multiple emissions. However, the emission spectra of the codoped QDs are difficult to control and the PL QYs are usually low because various ions get involved in the synthetic process and the resulting surface-defect emissions are extremely sensitive to the surroundings. , The interaction mechanism and the realization of high PL QYs of transition-metal-ion-codoped ternary QDs are of great research value.…”