Quantum dot light-emitting diodes with organic-inorganic hybrid charge transport layer (Conference Presentation)

Abstract

ZnO-based nanoparticles (NPs) are widely used as the electron transport layers (ETLs) for quantum dot light-emitting diodes (QLEDs) because of their advantages of high electron mobility and appropriate energy levels. However, QLEDs with ZnO ETLs suffer from unbalanced charge injection and interfacial exciton quenching. To address these issues, the ZnMgO NPs are doped by polyvinylpyrrolidone (PVP), which improves the morphology, reduces the conductivity and decreases the surface quenching sites of ZnMgO ETLs. As a consequence, QLEDs with ZnMgO:PVP hybrid ETLs exhibit a high current efficiency (CE) of 56.70 cd/A and a peak EQE of 13.36%, which are about 1.33-fold higher than those of the devices with ZnMgO ETLs. In addition, the ZnMgO NPs are effectively densified by doping PVP. Because of the improved compactness, the hybrid ETL can even withstand the plasma damage during indium-tin-oxide (ITO) sputtering, which thus enables the fabrication of transparent QLEDs. We also show that the formation of microfilaments can be eliminated by replacing the problematic ZnMgO with more compact ZnMgO:PVP composite. The developed ZnMgO:PVP composite, with improved compactness, tunable conductivity and reduced quenching sites, could be the ideal ETLs for efficient bottom-emission and transparent QLEDs.