Observed coexistence of memristive, memcapacitive and meminductive characteristics in polyvinyl alcohol/cadmium sulphide nanocomposites

Undoped and copper doped cadmium sulphide nanoparticles embedded in polyvinyl alcohol matrix (PVA/CdS) were synthesized by adopting chemical route. The effects of doping with Cu on the structural, optical and electrical properties of the as-prepared samples are reported. X-ray diffraction (XRD) results showed a mixed phase of cubic and hexagonal in the Cu-doped samples and only cubic phase was observed in the undoped sample. The estimated crystallite/particle size from the XRD, HRSEM and HRTEM is in the range of 2-10 nm. UV-Vis revealed blue shift of the absorption wavelength suggesting quantum confinement. Photoluminescence emission shows red shifting of emission peaks in Cu-doped PVA/CdS samples in comparison to undoped PVA/CdS. Two terminal electrochemical devices were fabricated, with the as-synthesized undoped and copper doped PVA/CdS NC samples as the active layer on ITO coated glass slide and silver (Ag) electrodes. I-V characteristics of the as-fabricated Ag/PVA/CdS NCs/ITO devices exhibit non-zero crossing hysteresis behaviour. The observed behaviour suggests co-existence of extended memristive characteristics with memcapacitive/meminductive characteristics classified as characteristic of extended memelements.