Ga-Doped SnO2 Electron Transport Layer with Tunable Mobility and Conductivity for High-Performance Inverted Quantum Dot Light-Emitting Diodes

Quantum-sized SnO 2 nanoparticles have been widely employed as electron transport layer (ETL) in high-efficiency quantum dot light-emitting diodes (QLEDs) owing to their attractive properties, such as high stability, wide bandgap, and excellent optical transparency. However, the device performance of SnO 2 -based QLEDs is still significantly lower to those of ZnO-based devices, suggesting considerable room for improvement. Here, we demonstrate the use of Ga-doped SnO 2 nanoparticles with tunable mobility and conductivity for constructing high-performance SnO 2 -based QLEDs. The influences of Ga-doping concentration on the mobility and conductivity of SnO 2 nanoparticles are systematically investigated. The mobility and conductivity of Ga-doped SnO 2 nanocrystals can be tuned over two orders of magnitude by varying Ga-doping level. This p-type doping strategy effectively suppresses excessive electron transport in the SnO 2 nanocrystals, thereby promoting more balanced charge injection within the QLED structure. As a result, red-emitting inverted QLEDs incorporating 3.5 at% Ga-doped SnO 2 nanocrystals achieve an average external quantum efficiency (EQE) of 17.36% and a peak EQE of 20.04%. These results suggest that Ga-doped SnO 2 nanocrystals are excellent candidates for the fabrication of high-performance QLEDs.