Thin copper selenide films were synthesized on polyamide sheets using the successive ionic layer adsorption and reaction (SILAR) method at three different temperatures. It was found that elevating the temperature of the solution led to the creation of copper selenide films with different features. X-ray diffraction characterization revealed that all films crystallized into a cubic Cu2−xSe, but with different crystallinity parameters. With elevating the temperature, grain size increased (6.61–14.33 and 15.81 for 40, 60 and 80 °C, respectively), while dislocation density and the strain decreased. Surface topology was investigated with Scanning Electron Microscopy and Atomic Force Microscopy, which revealed that the grains combined into agglomerates of up to 100 nm (80 °C) to 1 μm (40 °C). The value of the direct band gap of the copper selenide thin films, obtained with UV/VIS spectroscopy, varied in the range of 2.28–1.98 eV. The formation of Cu2−xSe was confirmed by Raman analysis; the most prominent Raman peak is located at 260 cm−1, which is attributed to binary copper selenides. The thin Cu2−xSe films deposited on polyamide showed p-type conductivity, and the electrical resistivity varied in the range of 20–50 Ω. Our results suggest that elevated temperatures prevent large agglomeration, leading to higher resistance behavior.

The spin-coating method has been employed for nanostructured crystalline zinc oxide (ZnO) thin film preparation on FTO glass substrates. Cadmium sulfide (CdS) layers were then deposited on the surface via the chemical bath deposition method. To investigate the effect of the formation of the CdS layer on ZnO/FTO, the deposition of these layers was performed at three different temperatures (40, 60, and 80 °C). The synthesized CdS/ZnO composite was found to have homogenously distributed crystalline grains of both ZnO and CdS. The uniform distribution of the grains and the equal molar ratio of the two components resulted in excellent optical and photocatalytic performance. Analysis of CdS/ZnO thin films was performed using XRD analysis, UV-vis spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and linear sweep voltammetry. The best optical, morphological, and electrical properties and the highest photocurrent value of the CdS/ZnO thin films were obtained when the CdS layers were formed at 60 °C. X-ray diffraction characterization revealed that CdS/ZnO thin films crystallized into hexagonal wurtzite ZnO and cubic CdS. The crystallite size of ZnO and CdS/ZnO was ~38 nm and ~19 nm, respectively. The band gap calculated for CdS/ZnO, formed at different temperatures, varies from 2.05 to 2.15 eV.