Development of Cu20 layers prepared by a low cost chemical method for use in photo-voltaic thin film devices

Abstract

A low cost and simple chemical method based on boiling copper plates in copper plates in C11SO4 solution is used to prepare CU2O layers on Cu substrates. X-ray diffraction (XRD), Scanning electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Glow Discharge Optical Emission Spectroscopy (GDOES) and Optical Absorption have been used to characterize these layers. It has been found that the layers consist of CU2O phase with a thickness of about 1.4 pm when the Cu plate is boiled in CUSO4 solution for 60 minutes. The largest grain sizes are in the order of 1 pm and the layers contain cubic C112O phases. The layers are n-type in electrical condition and the optical band gap observed is 2.2 eV. n-Cu20 films were prepared by boiling well cleaned copper plates in a (10'3 M) CUSO4 solution at different boiling periods, to obtain copper oxide films with nanocrystals and microcrystals films on 'the copper substrate. The resulting films were characterized by SEM and XKD measurements, p-type merocyanine dye films were deposited on n- Cu^O films to make a n-p junction. A photocurrent enhancement was observed in case of the nanocrystals n-Cu20/ p-merocyanine photoelectrode at the electrolyte (10‘4 M) (Fe27Fe3 redox couple was used at the electrolyte) interface due to the enhanced light absorption properties of the dye and the efficient charge separation at the n-p junction. Mechanisms involved for the photocurrent enhancement are discussed in detail.