Hot Injection-Based Synthesized Colloidal CdSe Quantum Dots Embedded in Poly(4-vinylpyridine) (PVP) Matrix Form a Nanoscale Heterostructure for a High On–Off Ratio Memory-Switching Device

Abstract

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 10 5 . 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.

Embedding Azobenzol-Decorated Tetraphenylethylene into the Polymer Matrix to Implement a Ternary Memory Device with High Working Temperature/Humidity

“…The strategy of integrating electrically active components with flexible polymers might realize the multilevel-memory performances because the stacking configurations of guest additives in supporting polymers could be modulated by eternal voltage. However, up to now, only binary memristors have been achieved in these guest additive@polymer systems (the additives include nanoparticles, carbon-based nanomaterials such as fullerenes or graphene, and small molecules), − which might be relative to the less barriers of these additives in polymers. Keeping this in mind, if the additive itself has multilevel resistive switching behavior and the thermally stable/hydrophobic polymer serves as the matrix, multilevel-memory devices with good environmental tolerance might be constructed.…”

CdSe Quantum Dot-Based Nanocomposites for Ultralow-Power Memristors

“…As a result, the conductive pathways are completely destroyed, and the device goes to the HRS again, ensuing the RESET process. The height of the energy barrier in the Al–PVP junction is lower than that of the indium tin oxide (ITO)–PVP junction, and this may be the reason for getting the low values of SET and RESET voltages in our device compared to those of the previously reported ITO\PVP-CdSe QD\Al device …”

“…The hot injection method with slight modifications was employed for the synthesis of the colloidal CdSe QDs as described before . In this process, first, 0.8 mmol cadmium oxide (CdO), 1 mL of OA, and 20 mL of ODE were taken in a 100 mL three-necked reaction flask.…”

“…Also, the utilization of core–shell CdSe\CdS and CdSe\ZnS QDs enhanced the performance of the RRAM device, but the current ON/OFF ratio was limited to 1000. , The CdSe\CdZnS core–shell structure in association with the organic polymer was used to fabricate a synaptic device for neuromorphic computing . Recently, the CdSe-poly­(4-vinylpyridine)­(PVP) composite-based device with indium tin oxide (ITO) and Al electrodes exhibited a high I ON/OFF , but the switching voltage was large …”

“…44 Recently, the CdSe-poly(4-vinylpyridine)(PVP) composite-based device with indium tin oxide (ITO) and Al electrodes exhibited a high I ON/OFF , but the switching voltage was large. 45 In this work, we have synthesized colloidal CdSe QDs by the hot injection method and made a nanocomposite of QDs and the PVP polymer to fabricate the Al\CdSe-PVP\Al RRAM device. Our RRAM device exhibits excellent bipolar nonvolatile resistive switching behavior within a very small switching voltage window (<±0.8 V) with a fast switching speed and high endurance.…”