A charge imbalance often occurs in quantum dot light-emitting diodes (QLEDs) owing to the difference in migration rate between the hole transport layer (HTL) and the electron transport layer. In this study, we inserted a Spiro-OMeTAD thin film, an organic polymer with a high lowest unoccupied molecular orbital energy level, between the HTL and quantum dot emission layer to block the transmission of excess electrons from the quantum dot luminescence layer to the HTL, which promotes the charge balance of the device, and thus a highly efficient new green QLED is fabricated. The results show that the new green QLED exhibits distinct improvements over the traditional devices, with an 87% improvement in external quantum efficiency up to 11.87%, and a 106% increase in brightness up to 53055 cd/m 2. This proves that blocking the transmission of excess electrons can significantly solve the charge imbalance problem in QLEDs.