Memory effect in carbon quantum DOT–PEG1500N composites

• Bare and PEG1500N functionalized carbon quantum dots show resistance hysteresis.
• Both systems show stable memory effect after large cycle number.
• Only functionalized carbon quantum dots show stable hysteresis with temperature.
• Transport mechanisms responsible for hysteresis were identified for both systems.

Electrical measurements performed on films of bare carbon quantum dots (CQDs) as well as of CQD functionalized with PEG1500N deposited on interdigitated electrodes reveal a significant resistance hysteresis. At room temperature, both systems present a stable memory effect after a large number of cycles, fact associated with the removal of shallow trapping states after the thermal treatment of bare and passivated CQDs films. Temperature analysis of transport properties shows that CQDs functionalized with PEG1500N present a stable hysteresis as the temperature increases, in contrast to the hysteresis of bare CQD films, which disappears at high temperatures. Several transport mechanisms responsible for the electrical behavior of these systems were analyzed and the role of PEG1500N as a passivation shell was discussed.