Inverted InP quantum dot light-emitting diodes using low-temperature solution-processed metal-oxide as an electron transport layer

The present work shows the inverted InP quantum dot light-emitting diodes (QD-LEDs) with inorganic metal oxide layers. In the inverted structure of ITO/ZnO/InP QDs/CBP/MoO₃/Al, a sol-gel derived ZnO film was used as an electron transport layer (ETL) and MoO₃ was used as a hole injection layer (HIL). In contrary to high annealing temperature (>200 °C) for conventional ZnO films, low temperature annealing (∼150 °C) was performed for sol-gel derived ZnO film. The performance of the inverted QD-LEDs was efficiently improved by optimization of the annealing time and temperature of ZnO ETL. The current efficiency was significantly improved about 215% by lowering annealing temperature of ZnO ETL.