Inserting an insulating layer between the charge transport layer (CTL) and quantum dot emitting layer (QDL) is widely used in improving the performance of quantum dot light-emitting diodes (QLEDs). However, the additional layer inevitably leads to energy loss and joule heat. Herein, a monolayer silane coupling agent is used to modify the said interfaces via the self-limiting adsorption effect. Because the ultrathin layers induce negligible series resistance to the device, they can partially passivate the interfacial defects on the electron transport side and help confine the electrons within the QDL on the hole transport side. These interfacial modifications can not only suppress the nonradiative recombination but also slow down the aging of the hole transport layer. The findings here underline a low-temperature adsorption-based strategy for effective interfacial modification which can be used in any layer-by-layer device structures.