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.