Ga‐Doped SnO ₂ Electron Transport Layer with Tunable Mobility and Conductivity for High‐Performance Inverted Quantum Dot Light‐Emitting Diodes

ABSTRACT 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.