Abstract: Quantum dot (QDs) based light-emitting diode devices (QLEDs) attracted significant academic interest due to their outstanding color saturation and convenient solution-based manufacturing processes. At present, the external quantum efficiency (EQE) of cadmium-based red, green and blue QLEDs has reached the theoretical limit, but there is still severe carrier injection imbalance, which will lead to a significant reduction in the stability and lifetime of the device. In this work, the electron transport layer (ETL) is doped by a simple method to reduce the electron mobility and achieve a more balanced carrier injection. When an appropriate amount of ethanolamine (EA) solution is added to the ethanol solution of ZnMgO, the amine ion (NH₂⁻) can fill the oxygen vacancy in ZnMgO, thereby regulating the electron mobility of ZnMgO. Compared with the control device, the EQE of the optimized device increased to 14.6%, the current efficiency (CE) increased to 60.7 cd/A, increased by 1.87 times and 1.94 times respectively, and the peak brightness reached 252402 cd/m².