Effect of Temperature on the Synthesis of Copper Oxide (I) Thin Films by Silar Method

In this work, copper oxide (I) (Cu2O) thin films are deposited by SILAR method at different temperatures (40, 50, 60, 70°C) on a glass substrate through 20 immersion cycles. Temperature of the 2M NaOH solution ranged from 40–70°C, while that of the copper solution was maintained at room temperature. The effects of temperature are examined in terms of the change in optical, structural and morphological properties of the films. Optical properties of the films were determined in the wavelength range of 300-1100 nm at room temperature by UV/vis spectrophotometer. Optical transmittance values of Cu2O thin films in the visible region were detected to be between 13-42%, whereas refractive indices (n) were calculated to be between 2.8-4.9. Film thicknesses calculated by gravimetric analysis were found to be between 170 and 520 nanometers. Energy band gap values (Eg) of the films ranged between 2.18-2.43 eV. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all of the films exhibited polycrystalline structure with cubic phases and covered the glass substrates well. The crystalline structure and morphology of the films improved by increasing the temperature of the NaOH solution. The results of this study showed that increasing the solution temperature has improved the physical properties of Cu2O thin films produced by the SILAR method. The optical analysis of Cu2O thin films obtained by the SILAR method shows that these films are suitable for photovoltaic solar cells in terms of their low optical transmittance values and wide band gaps