Abstract
In this work, the Cu-Sn-Mn multicomponent oxide thin film deposited from earth-abundant, stable, eco-friendly compound, CuO, SnO2, MnO2, were presented. The applications as an electrode for photoelectrochemical cell and as a material for degradation pollutant were also demonstrated. The synthesis and characterization of Cu-Sn-Mn-O thin film were investigated in this study. By controlling the composition of target, Cu-Sn-Mn-O thin films showed more than 104 cm-1 absorption coefficient in wavelength of 400 nm to 700 nm, in visible light region by UV-Vis analysis. The thin films were further investigated by ultraviolet photoelectron spectroscopy (UPS), photoluminescence (PL), cathodoluminescene (CL). The Ev (valence band energy), Ec (conduction band energy) band position of thin films, deposited from target composition of Cu : Sn : Mn = 3 : 1 : 3, was characterized as 6.7 eV, 4.4 eV, respectively, and the Eg (band gap) was measured to be 2.3 eV. Carrier concentrations of Cu-Sn-Mn-O thin films could be reduced between 1019 to 1021 cm-3 after annealing and oxidation process. By grazing incident X-ray diffractometer (GIXRD) analyses, Cu-Sn-Mn-O thin film verified as a composite containing CuO, Cu2O, SnO2, MnO, and Mn3O4. The solar energy applications were investigated by JSV (linear sweep voltammetry), J-t (photocurrent-time curve), and photodegradation experimental tests. The best result showed a current density of 0.042 mA/cm2 under visible light excitation with good stability, and near 0.1 mA/cm2 under solar light excitation but lack of good stability. The rate constant of RhB degradation was 1.72 x 10-3 min-1 under 365 nm UV-light excitation, and 6.9 x 10-4 min-1 under visible light excitation. The rate constant of MO degradation was 2.3 x 10-3 min-1 under visible light excitation. The Cu-Sn-Mn-O thin films developed in this work showed the potential of water splitting under solar light.