Here we present for the first time a TiO2/Cu2O all-oxide heterojunction solar cell entirely produced by
spray pyrolysis onto fluorine doped tin oxide (FTO) covered glass substrates, using silver as a back
contact. A combinatorial approach was chosen to investigate the impact of the TiO2 window layer and
the Cu2O light absorber thicknesses. We observe an open circuit voltage up to 350 mV and a short circuit
current density which is strongly dependent of the Cu2O thickness, reaching a maximum of 0.4 mA/
cm2
. Optical investigation reveals that a thickness of 300 nm spray pyrolysis deposited Cu2O is sufficient
to absorb most photons with an energy above the symmetry allowed optical transition of 2.5 eV,
indicating that the low current densities are caused by strong recombination in the absorber that
consists of small Cu2O grains.