Electrochemical luminescence of ZnGa2O4 and ZnGa2O4:Mn electrodes

Semiconductor electrodes of ZnGa2O4 and ZnGa2O4:Mn were prepared by reducing ZnGa2O4 and ZnGa2O4:Mn sintered disks in a hydrogen stream. Under cathodic polarization in S2O82− electrolyte solution, electrochemical luminescence (ECL) was observed with a peak at 485 and 500 nm for the ZnGa2O4 and ZnGa2O4:Mn electrodes, respectively. With increasing cathodic polarization, the 500 nm emission for the ZnGa2O4:Mn electrode shifted to 490 nm. The ECL is ascribed to the recombination between the electrons in the conduction band and the holes in the valence band for ZnGa2O4 or their recombination that takes place at the Mn2+ site for ZnGa2O4:Mn.