Structural, optical, electrical, and photoelectrochemical properties of cuprous oxide thin films grown by modified SILAR method

In this work, cuprous oxide (Cu2O) thin films have been grown on both soda lime glass (SLG) microscopy slides and Fluorine doped Tin Oxide (FTO) substrates by a modified SILAR method. The pH level of the cationic precursor, adjusted by adding acetic acid and sulfuric acid separately, as well as the concentration of anionic precursor (NaOH) were varied to elucidate their effect on the physical properties of the deposited films. The XRD measurement shows that all films were polycrystalline in nature but single phase Cu2O with (111) preferred orientation. The surface morphology examined by scanning electron microscopy (SEM) revealed that the deposited films are micro-crack and pin hole free and coherently carpet the underlying substrate. The estimated optical band gap and resistivity of the deposited products were found to be in the range of 2.05-2.16 eV and 180-380 O. cm respectively where the latter is at least one order of magnitude less than the reported results for Cu2O thin films grown by similar methods. Both the optical band gap and electrical resistivity were found to be decreasing with decreasing the pH level of the cationic precursor solutions and attributed to the improve crystallization of the deposit. The LED ON/OFF modulated transient surface photovoltage of modified SILAR grown Cu2O electrode shows p-type conductivity consistent with hot point probe results and these photocathodes were found to be stable over more than 1 h in a Photoelectrochemical cell filled with aqueous electrolyte.