Photoluminescence characterization of polycrystalline n-type Cu2O films

Electrodeposition was used to deposit Cu2O thin films on ITO substrates. Photoresponse of the film clearly indicated n-type behavior of Cu2O in photoelectrochemical cells. The temperature dependence of photoluminescence (PL) revealed that the spectra consist of donor–acceptor pair emissions and the recombination between electrons bound to donors and free holes. We observed that the dominant intrinsic defect, oxygen vacancies, creates a donor energy level at 0.38 eV below the bottom of the conduction band. As a result, this donor level acts as a center for both PL emissions and to produce n-type conductivity in the electrodeposited Cu2O films. In addition, an acceptor energy level at 0.16 eV from the top of the valence band was observed.