Effect of Tellurium Doping on Optoelectronic Properties of Blue ZnTeSe Quantum Dots

Quantum dot light emitting diodes (QD-LEDs) have high potential to be used in next-generation displays. The main challenge in the commercialisation of QD-LEDs is the improvement of the efficiency and stability of blue QD-LEDs. The most promising emitter for blue QD-LEDs is ZnTeSe QD, however it is concerned that tellurium causes spectral broadening and efficiency drop. In this work, we demonstrate the effect of Te clusters on the electronic structures of blue ZnTeSe QDs through first principle calculation. The photo dynamics at the ensemble and single dot level show that the lifting of hole-state degeneracy in Te-doped structures causes slow relaxation and peak emission shift. Furthermore, the strong confinement of hole wave functions in Te clusters improves the efficiency and stability of QD-LEDs by suppressing QD luminescence quenching under electrical bias. The understanding of the correlation between the photophysical nature of Te-doped QDs and device performance can provide a basis for designing blue-emitting QD structures that are suitable for practical QD-LEDs.