The outcomes of Zn doping on the properties of CuO thin films prepared via modified SILAR method and its impact on the performance of CuO-based solar cells using Cd_0.4Zn_0.6S-ETL and Spiro-OMeTAD-HTL

Doping is a highly effective tool for modifying the properties of semiconductor thin films. This study quantitatively examines the effect of zinc (Zn) doping on the physical properties of copper oxide (CuO) thin films prepared using a modified SILAR method. The crystalline structure, morphology and optical properties of the obtained samples were further characterized using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and UV–visible spectrometry. XRD analysis confirmed the inclusion of Zn into the CuO crystal lattice without altering its monoclinic structure, and no secondary phases such as Cu \(_{2}\) $_2^{}$ O, Cu(OH) \(_{2}\) $_2^{}$ , or ZnO were detected, indicating high-quality films. SEM images reveal that surfaces are uniformly coated, dense and compact with uniform distribution of grains. EDX spectrum and mapping analysis verified the incorporation of Zn atoms into CuO thin films. In addition, the UV–Visible spectroscopy a significantly indicated an increase in transmission and enhanced the bandgap from 1.47 to 1.55 eV with an increase in Zn concentration. The impact of Zn doping on the refractive index and the Urbach energy of CuO nanostructures has been investigated. Zn doping improved the optical properties of the films without trading off the tenorite phase of CuO thin films making them suitable in solar cells applications. Additionally, the impact of Zn-doped CuO on solar cell performance was investigated using the SCAPS-1D program. A novel heterostructure (ITO/Cd \(_{0.4}\) $_{0.4}^{}$ Zn \(_{0.6}\) $_{0.6}^{}$ S/Zn:CuO/Spiro-PMeTAD/Au) designed for CuO-based solar cells was analysed. Firstly, Cd \(_{1-x}\) $_{1-x}^{}$ Zn \(_{x}\) $_x^{}$ S was investigated as a factor affecting the performance of undoped CuO solar cells. Simulation results demonstrated that increasing Zn doping in CuO enhances solar cell efficiency. Finally, the proposed heterostructure design exhibits promising advancements, highlighting the potential for enhancing solar cell efficiency through targeted material doping and precise heterostructure engineering.