Simultaneous achievement of high efficiency and brightness at low bias in red InP/ZnSe/ZnSeS/ZnS quantum dot light-emitting diodes

Abstract

As an exceptional class of Cd/Pb-free energy-efficient devices, the InP-based quantum dots light-emitting diodes (QLEDs), show promising prospects in display and lighting. However, their red QLEDs achieve high external quantum efficiency (EQE) over 20 % at low luminance. In this study, we develop a water-controlled Mg²⁺ doped ZnO nanocrystals (ZMO NCs) synthetic route to effectively control the surface oxygen vacancies, which related to the conductivity of ZMO electron transfer layer (ETL). Additionally, both ZnSe and ZnSe_0.75S_0.25 shells are introduced to alleviate lattice stress between the InP core and ZnS shell while enhancing photostability. Ultimately, we achieved a peak EQE of 20.9 %, accompanied by a luminance of 2905.4 cd/m² at 3.4 V and a highly efficient luminance (EFL) of 60,722.9. The T₅₀ operational lifetime is calculated to be 274,998 h (equivalent to around 31 years) at an initial luminance level of 100 cd/m² by applying an acceleration factor of 1.8. The simultaneously high luminance and high EQE at a low drive voltage may efficiently reduce the power consumption.