Optical, structural, and photoelectrochemical properties of nanostructured Cl-doped Cu2O via electrochemical deposition

Abstract

In this work, we report on the synthesis of cuprous oxide (Cu2O) thin films from sulfate bath on fluorine doped tin oxide glass (FTO/glass) substrates with different concentrations of copper chloride (CuCl2) by electrochemical deposition. The effects of CuCl2 concentrations were investigated by X-ray diffraction (XRD), atomic force microscope (AFM), UV–Vis transmittance, capacitance measurements (i.e., Mott-Schottky (M-S) plots), photocurrent and electrochemical impedance spectroscopy. The measurements of X-rays diffraction (XRD) showed that the Cu2O films are pure and have a monocrystalline structure. The M-S plots demonstrate that the conduction type of the Cu2O films changes with increasing the carrier density by increasing CuCl2 concentration in the deposition bath. Photocurrent measurements confirm that Cl-doped Cu2O films are n-type semiconductors excepted for Cu2O doped with 0.005 M. Changes in the photocurrent response and the electronic disorder were discussed as a function of CuCl2 concentration. It was found that the highest n-type photocurrent density of 0.045 mA/cm2 and the lowest charge transfer resistance (Rct) was obtained when the concentration of CuCl2 was 0.01 M. Carrier density of Cu2O films varied between 1.41 × 1020 to 1.69 × 1020 cm−3 when the CuCl2 concentration was between 0.01 and 0.03 M. The optical measurements show a direct band gap depending on the concentration of CuCl2. The solution based doping method is particularly suitable for large area, low cost, and high throughput fabrication of Cu2O solar cells.