Improving the conductivity of cuprous oxide thin film by doping Calcium via feasible nebulizer spray technique for solar cell (FTO/ZnO/Ca-Cu₂O)

Calcium-doped cuprous oxide (Ca:Cu₂O) thin films were effectively coated onto glass substrate by nebulizer spray technique with different doping percentage (0%, 1%, 2% and 3%). X-ray beam diffraction confirms the polycrystalline nature of the prepared Cu₂O thin film. An increase in size of the crystallites from 11 nm to 29 nm was observed for the increase of doping concentration. AFM study exposed a smooth surface with evenly dispersed grains and the change in roughness on the film surface was also noticed. Optical measurements showed the band gap varied from 2.40 eV to 2.15 eV for undoped and doped films. All the films were with narrow emissions band at 630 nm for excitation at 450 nm from the PL spectra. Hall Effect measurements showed that the prepared films have p-type conducting nature with resistivity value of 0.453 × 10² Ω cm and the carrier density of 21 × 10¹⁹ cm⁻³ for the 3% Ca-doping concentration. Solar cell characteristics such as an open circuit voltage (V_oc) of 0.30 mV, fill factor (FF) of 0.33 and conversion efficiency (η) of 0.45% were attained for 3% Ca doped Cu₂O film. (paper)