Highly Efficient and Stable Quantum Dot Light-Emitting Diodes Employing Sputtered SnO2 Layer as Electron Transport Layers

We report a novel approach to fabricating high-performance and robust quantum dot light-emitting diodes (QLEDs) utilizing sputtered SnO2 thin films as the electron transport layer (ETL). While conventional solution-processed ZnMgO NP ETLs face limitations in mass production, the sputtering process offers advantages for uniform and reproducible thin film deposition. Herein, the structural, optical, and electrical properties of SnO2 thin films were optimized by controlling the Ar/O2 ratio and substrate heating temperature during sputtering. SnO2 thin films with O2 gas improve charge balancing in QLEDs by lowering the conduction band minimum. Furthermore, it was observed that oxygen vacancies in SnO2 function as exciton quenching sites, which directly impacts the long-term stability of the device. QLEDs fabricated under optimal conditions (Ar/O2 = 35:5, 200 °C heating) achieved a peak luminance of 99,212 cd/m2 and a current efficiency of 21.17 cd/A with excellent device stability. The findings suggest that sputtered SnO2 ETLs are a highly promising technology for the commercial production of QLEDs.