Liquid junction characterization of CuGaSe2 thin films

Photoelectrochemical techniques were used to characterize photovoltaic thin films of CuGaSe₂. The use of an acidic electrolyte with an imposed potential form a 0.06 M V²⁺/V³⁺ redox couple, but containing a considerable amount of Zn²⁺, has led to results which may be interpreted by the existence of a large bandgap surface layer. Surface analysis techniques have shown that this layer cannot be native of the CuGaSe₂, but must be due to interreaction with the electrolyte, since electrolyte species (Zn) have been found on the films after characterization. Nevertheless, the photocurrents collected at the interface have comparable values to those obtained on solid-state devices, and their analysis leads to determination of values for the bandgap energies that show a clear dependence on sample composition. It is believed that this surface modification may be used for solid-state devices