Organic dye-sensitized f-MWCNTs-TiO2 composite for optically controlled resistive switching memory applications

Herein, we have developed organic dye (turmeric) sensitized functionalized multi-walled carbon nanotubes (MWCNTs)-titanium dioxide (TiO2) composite and investigated it's optically controlled resistive switching (RS) and non-volatile memory properties. The composite was synthesized using a single-step hydrothermal method and the dye sensitization period was varied to investigate the effect of the dye loading time (6, 12, 18, and 24 h) on the different properties of the composite. The structural, morphological, and optical properties of the bare and dye-sensitized composites were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and UV–visible spectrometer. The electrical properties of the bare and dye-sensitized composite based devices were tested in the dark, UV, visible, and UV + visible light illumination conditions. Due to the good absorbance properties of the TiO2 in UV region and dye in the visible region, the dye-sensitized composite devices show excellent bipolar RS and non-volatile memory properties in the UV + visible light illumination condition. In this work, the 18 h dye-sensitized device shows superior optical RS properties than other devices. The memristive properties of the optimized devices are reported and demonstrated that the UV + visible light illumination condition provides double valued charge-flux property and best in class charge driving capability. The electrical transport and possible optically controlled RS mechanisms are discussed. The results suggested that the optical stimulus can be an additional parameter in conjunction with the electric stimulus to control the RS properties of the devices.