Interface Modification by Cs₂CO₃ Buffer Layer in Electroluminescent Quantum Dot Light-Emitting Diodes with Metal-Oxide Carrier Transport Layers

摘要

In this article, the quantum dot (QD) light-emitting diodes (QDLEDs) with ZnO electron transportlayer (ETL) and MoO3 hole transport layer (HTL) were demonstrated. With adequate mixing of 0.1 Mzinc acetate dihydrate and monoethanolamine (MEA) in ethyl alcohol, the ZnO ETL was readilyfabricated on indium tin oxide (ITO)/glass substrates by sol-gel method. To achieve balanced electronand hole injection, Cs2CO3 and 4,4'-di(N-carbazolyl)biphenyl (CBP) layers were inserted prior to thedeposition of QD and MoO3 layers, respectively. Our device structure can be simply depicted asITO/ZnO/Cs2CO3/QD/CBP/MoO3/Au. It was found that the Cs2CO3 buffer layer played an importantrole to facilitate radiative recombination and reduce the leakage current due to the poor quality of sol- gel fabricated ZnO thin films. The analysis of surface morphology of Cs2CO3 layers showed thatZnO/QD interface can be effectively formed for electron injection only when the Cs2CO3 layer wasannealed properly. With our demonstration, QDLEDs with ZnO ETL and MoO3 HTL can be apromising device structure for realizing QDLED commercial application.