Construction of electron and grain boundary barrier in quantum dots light-emitting diodes: The role of NiO interface coating

Abstract NiO nanocrystals (NCs) thin film is applied as an electron barrier layer (EBL) for red quantum dot light-emitting diodes (QLEDs) to decrease the leakage current and balance the carrier transportation. The optimized NiO-based QLED exhibits the external quantum efficiency (EQE) of 5.85%, current efficiency (CE) of 6.9 cd A−1, with a maximum luminance of 31772 cd m−2, demonstrating that NiO is an effective EBL for QLEDs. The electron barrier height of 0.031 eV can effectively block 70% electron transport thanks to form the electron trap, grain boundary and depletion layer. The mechanism of the electron transport through NiO EBL is quantum tunneling, which is consistent to Richardson Schottky thermal injection model.