Chalcogenide-based quantum dots are useful for the application of memory-switching devices because of the control in the trap states in the materials. The control in the trap states can be achieved using a hot-injection colloidal synthesis method that produces temperature-dependent size-variable quantum dots. In addition to this, formation of a nanoscale heterostructure with an insulating material adds to the charge-trapped switching mechanism. Here, we have shown that the colloidal monodispersed CdSe quantum dots and poly(4-vinylpyridine) (PVP) formed a nanoscale heterostructure between themselves when taken in a suitable ratio to fabricate a device. This heterostructure helps realize memory-switching in the device with a maximum on-off current ratio of 105. The switching in the device is mainly due to the trap states in the CdSe quantum dots. The conduction in the off state is due to thermal charge injection and space charge injection conduction and in the on state, due to the Ohmic conduction mechanism. © 2021 American Chemical Society.