Performance Enhancement of InP Quantum Dot Light-Emitting Diodes via a Surface-Functionalized ZnMgO Electron Transport Layer

Most state-of-the-art quantum dot light-emitting diodes (QLEDs) adopt metal oxide nanoparticles (NPs) as the electron transport layer (ETL). However, such ETL materials usually entail not only charge unbalance in the quantum dot (QD) emitting layer (EML) but also exciton quenching at the EML/ETL interface. To solve the above troubles, herein, the surface modification of ZnMgO NPs is implemented with an acrylate functional species. The acrylate functionalization is found to not only mitigate the emission quenching at the EML/ETL interface but also upshift the energetic positions of ETL in favor of charge balance. The red QLED with ZnMgO NPs functionalized with an optimal content of surface acrylate produces markedly enhanced electroluminescent performance (specifically, 16 954 cd/m2 in luminance and 12.0% in external quantum efficiency) relative to the control device with pristine ZnMgO NPs. The applicability of acrylate-functionalized ZnMgO NPs to green InP QLEDs is further tested, verifying the universal validity of the present surface modification of ETL materials over red and green devices.