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

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 ZnSe0.75S0.25 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.