Fabrication of oxidized CuO and spray-pyrolyzed TiO2 heterojunction thin film

A heterojunction device was fabricated via oxidation of a thin film and spray pyrolysis. In this work, a copper oxide (CuO) film was grown via magnetron sputtering of Cu film deposited on pre-cut glass substrates and subsequent oxidation at 450 degrees C in air. A titanium dioxide (TiO2) film was deposited on the CuO film via spray pyrolysis of titanium (IV) isopropoxide precursor at 200 degrees C. X-ray diffraction analysis revealed the formation of monoclinic CuO film and tetragonal anatase TiO2 film. Scanning electron microscopy images showed agglomerated grains for both films with TiO2 grains larger than CuO grains. I-V characteristic of the CuO-TiO2 heterojunction film exhibited a rectifying behavior with a turn-on voltage of around 1.3 V and an ideality factor of around 1.96. The heterojunction revealed an open circuit voltage of around 0.59 V and a short circuit current of 0.3 mA under 100 mW/cm(2) solar light irradiation.