All-inorganic Quantum-dot Light-emitting Diodes with Reduced Exciton Quenching by a MgO Decorated Inorganic Hole Transport Layer.

Here, wide-bandgap magnesium oxide (MgO) is employed as a decorator for the nickel oxide (NiOx) hole transport layer (HTL), by means of a bulk dopant as well as a surface modifier. QLEDs with Ni0.88Mg0.12Ox serving as the HTL achieve a ~19.5 % efficiency improvement compared to devices using pristine NiOx. Further inserting an ultrathin MgO layer between the Ni0.88Mg0.12Ox and QDs to separate the accumulated charges from excitons goes on boosting the peak efficiency by another ~35 %. Finally, a maximum brightness over 40000 cd/m2 at 10 V is obtained, which is the highest among the reported values.