Drop-dry deposition of Co3O4 and fabrication of heterojunction solar cells with electrochemically deposited ZnO

Cobalt oxide (Co3O4) thin films were fabricated by the drop-dry deposition (DDD) method using an aqueous solution containing Co(NO3)(2) and NaOH. DDD was performed by dropping the solution on a substrate, heating-drying, and rinsing in water. The as-deposited film was Co(OH)(2), and it was converted to Co3O4 by annealing in air. The Raman and x-ray diffraction peaks of Co3O4 were observed for the annealed films. We also fabricated Co3O4/ZnO heterojunction solar cells with ZnO prepared by the electrochemical deposition method. The heterojunction had rectification properties and a weak photovoltaic response. Thus, DDD is promising for fabricating Co3O4 layers, and the Co3O4/ZnO heterojunction can be used as a solar cell.