Efficient Quantum-Dot Light-Emitting Diodes Based on Solvent- Annealed SnO2 Electron-Transport Layers

Due to the sensitivity of ZnO nanoparticles to water and oxygen, the hybrid quantum-dot light-emitting devices (QLEDs) based on ZnO electron-transport layers (ETLs) suffer from shelf stability and uncontrollable positive aging problems. Tin oxide (SnO2) is considered as an ideal alternative to ZnO as the ETL in QLEDs to improve their shelf stability. Currently, the SnO2-based device still suffers from poor efficiency. Herein solvent vapor annealing (SVA) is employed to reduce the roughness of SnO2 nanoparticle films, which suppresses the leakage current and enhances the device performance. Compared with the device with pristine SnO2, the maximum brightness and current efficiency (10.8 cd/A) of QLEDs based on solvent vapor annealed SnO2 are enhanced by 25.3% and 36.6%, respectively, being comparable to the ZnO device (11.0 cd/A). Moreover, SVA processing also has a positive effect on the device shelf stability, which is attributed to the dense interface between SnO2 and quantum dots due to the reduced surface roughness of SnO2 films.