Cu2Te/CoTe nanoparticles with tuneable bandgaps: Implications for photovoltaic and optoelectronic devices

Herein, we report the structural, optical, and electrochemical response of Cu2Te/CoTe nanoparticles synthesized by the facile microwave synthesis method by varying Cu and Co concentrations. Various characterizations such as Rietveld-refined X-ray diffraction, Raman Spectroscopy, and Transmission electron microscopy analysis infer the two hexagonal phases Cu2Te and CoTe having space group p6/ mmc and P63/ mmc, respectively. The elemental Energy-dispersive X-ray and X-ray photoelectron spectroscopy confirm the composition of all the elements. Field emission scanning electron microscopy images exhibit nanoparticles that remain unaltered even after the essential concentration variation. However, the differential scanning calorimetry study analyses the phase change of the material from room temperature to higher temperatures. Meanwhile, from UV-Vis spectroscopy, the optical band gap increases, and the refractive index value decreases in both the cases, Tauc plot, as well as Kubelka-Munk plot by varying Cu and Co concentrations, which shows well-defined properties that enable the material for various solar cell and optoelectronic applications. In addition, the electrochemical impedance spectroscopy analysis of the as-prepared material reveals small kinetic at high-frequency regions that can be used as the charge transfer of the electrode-electrolyte interface. The tuneable structural, optical, and electrochemical response of the CuCoTe nanomaterial broadens the advanced optoelectronic application prospects.