Electrochemical Self-Assembly of Nanostructured CuSCN/Rhodamine B Hybrid Thin Film and Its Dye-Sensitized Photocathodic Properties

Nanostructured hybrid thin films of CuSCN and rhodamine B (RB) are electrochemically self-assembled (ESA) by cathodic electrolysis in an ethanol/water mixture containing Cu2+, SCN-, and RB. By selecting the solvent, Cu2+/SCN- ratio, and the concentration of RB, we demonstrate several control parameters in the film formation. High loading of RB into the film has been achieved to reach a CuSCN:RB volume ratio of approximately 2:1. The RB solid could almost completely be extracted from the hybrid film by soaking the film in dimethylacetamide (DMA), leading to a large increase of the surface area. The crystallographic orientation of the nanostructure with respect to the substrate can be controlled. Efficient quenching of fluorescence of RB has been observed for the CuSCN/RB hybrid film, implying hole injection from RB excited state to CuSCN. Photoelectrochemical study on the porous crystalline CuSCN obtained after the DMA treatment and sensitized with RB revealed sensitized photocathodic action under visible light illumination, indicating the potential usefulness of the porous CuSCN electrodes for construction of tandem dye-sensitized solar cells.