Role of Al doping in morphology and interface of Al-doped ZnO/CuO film for device performance of thin film-based heterojunction solar cells

Abstract

Al-doped ZnO (AZO) at different doping concentrations are synthesized by the chemical bath deposition process. The X-ray diffraction results are confirmed the formation of hexagonal structure of ZnO. The doping concentration of Al in ZnO is varied the shape and size of AZO structures. These AZO structures are used for the fabrication of the heterojunction (ZnO/CuO) solar cell. The photoluminescence results are shown a smaller number of defects in AZO thin films. The potential barrier and ideality factor are obtained at 0.855 eV and 2.89 for 3 mol% doping of Al-doped thin-film solar cell diode. The interface of ZnO/CuO is analyzed by impedance spectra and Capacitance-frequency results. The maximum efficiency for device is recorded with a high fill factor at 3 mol% Al doped ZnO thin film based solar cell. This increased in the power conversion efficiency of device is originated from enhanced the optical properties, outstanding charge extraction efficiency, and suppressed the recombination of charge on the interface of CuO and AZO (3 mol%) layers, as revealed by the measurement of electrical, optical, and impedance spectroscopy.