Chen Lin, Mengxin Liu, Yixin Liu, Xin Su, Xinan Shi, Daocheng Pan
Quantum-sized SnO 2 nanoparticles have emerged as a promising electron transport layer (ETL) in quantum dot light-emitting diodes (QLEDs) due to their high chemical stability, wide bandgap, and high electron mobility. However, their excessive electron mobility often leads to charge transport imbalance, thereby limiting the device performance. Herein, we report a p-type doping strategy using Mg 2+ ions to modulate the electron transport capability of SnO 2 nanocrystals. By varying Mg-doping concentration, we achieve a wide-range tuning of electron mobility and conductivity over nearly 3 orders of magnitude. This suppression of electron transport enables the balanced charge injection in inverted QLEDs. As a result, red-emitting devices incorporating 2.0% Mg-doped SnO 2 ETLs exhibit an average external quantum efficiency (EQE) of 19.35% and a peak EQE of 22.04%. This work demonstrates Mg-doped SnO 2 nanoparticles as a superior alternative to ZnO nanoparticles for highly efficient and stable QLEDs.