Facile synthesis of Cu2O and CuO nanoparticles and study of their structural, optical and electronic properties

Two stable forms of copper oxides namely, CuO and Cu2O are potential materials for optoelectronic application, particularly for photovoltaics, due to their large absorption coefficient (α ∼ 105 cm−1) and broad absorption spectra covering a wide spectral range (from UV to NIR). Additionally, these materials are environmentally benign, stable and are available at low cost. Oxides of copper, therefore have been explored for their possible application in variety of directions including photovoltaics and gas-sensing. Here we developed an easy and environment friendly synthesis protocol for nanoparticles of both types of copper oxide and investigated in detail their structural, optical and electronic property. Synthesized materials were characterized using X-ray diffraction, SEM, TEM, FTIR-spectroscopy and UV-Vis reflectance measurements. Theoretical modeling tool based on density functional theory (DFT) has been used for deeper understanding of the semiconducting nature of these materials. For detail characterization, the as-synthesized nanoparticles of Cu2O was used without further annealing treatment and consequently was found to have smaller sized crystalline grains and higher degree disorder as compared to CuO. Electronic structure calculations confirmed the semiconducting nature for both the oxides with the occurrence of direct bandgap. These results are promising as they demonstrate an easy synthesis protocol to obtain crystalline nanoparticles of CuO. The crystallinity of Cu2O obtained in this study is inferior and can be improved via further annealing in inert atmosphere.