Cu[sub.2]O Homojunction Solar Cells: Efficiency Enhancement with a High Short Circuit Current

Cu[sub.2]O homojunction solar cells were fabricated using potentiostatic electrodeposition technique. n-Cu[sub.2]O thin films were grown in an acetate bath while p-Cu[sub.2]O thin films were grown in a lactate bath. In the growth of n-Cu[sub.2]O films, cupric acetate concentration, pH and temperature of the bath, deposition potential and duration (film thickness) and annealing temperature were investigated. In the growth of p-Cu[sub.2]O on n-Cu[sub.2]O, concentration of copper sulphate and lactic acid solutions, pH and temperature of the bath, deposition potential and duration were investigated. In addition, the procedure of sulfidation of p-Cu[sub.2]O film surface using (NH[sub.4])[sub.2]S vapor, before depositing Au front contact, was also optimized to enhance the photoactive performance. The structural, morphological and optoelectronic properties of the Cu[sub.2]O films were investigated using scanning electron microscopy (SEMs), high energy X-ray diffraction (HEXRD), hard X-ray photoelectron spectroscopy (HAXPES), spectral response and current–voltage (J-V) measurements. The best Cu[sub.2]O homojunction solar cell exhibited V[sub.oc] = 460 mV, J[sub.sc] = 12.99 mA·cm[sup.−2], FF = 42% and η = 2.51%, under AM 1.5 illumination. Efficiency enhancement with the record high J[sub.sc] value for the Cu[sub.2]O homojunction solar cell has mainly been due to the optimization of pH of the n-Cu[sub.2]O deposition bath and lactic acid concentration of the p-Cu[sub.2]O deposition bath.