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

Abstract

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.

High‐Performance Semitransparent Perovskite Solar Cells with 10% Power Conversion Efficiency and 25% Average Visible Transmittance Based on Transparent CuSCN as the Hole‐Transporting Material

“…As presented in Figure 1 a, CuSCN thin films exhibit smooth and continuous surface (with a RMS roughness of 7.5 nm) composed of nanocrystalline domains. The XRD pattern (Figure b) of distinct peaks at 2 θ = 16.1°, 27.2°, 30.3° are corresponding to the typical diffractions of (003), (101), (012) planes, revealing the formation of rhombohedral phase (β‐phase) in CuSCN thin films . Figure c shows light absorption of CuSCN and PEDOT:PSS thin films at the same thickness.…”

Electronic Properties of Copper(I) Thiocyanate (CuSCN)

“…Electrodeposition-based methods have been shown to be able to tune the orientation between the (001)-terminated and (101)-terminated surfaces [(001) or (101) planes parallel to the substrate surface, respectively, ( Figure 5)]. [45,46] Although for solution-grown CuSCN films the evidence is not yet clear due to the often small layer thicknesses, results also indicate the presence of (101) or (001) surface-oriented crystals. [11,33] Computational results suggested that the (101)-and (001)-orientations of hexagonal β-CuSCN could be stable especially when terminated with Cu, but the most stable surfaces were (100) and (110).…”

Concerted Photoluminescence of Electrochemically Self-Assembled CuSCN/Stilbazolium Dye Hybrid Thin Films

“…Cathodic electrodeposition of CuSCN thin films has already been well established and understood. 9,11,16,23 A 1:1 complex between Cu 2+ and SCN – ions, denoted as [Cu(SCN)] + , is spontaneously formed by dissolving equal molar amounts of Cu(ClO 4 ) 2 and LiSCN in alcohol such as methanol and ethanol. This complex is the active species to be reduced at the electrode to precipitate CuSCN with a Faradic efficiency of practically 100%.…”

“…17 Indeed, dye-sensitized photocathodic current was observed for a porous CuSCN sensitized with RB. 9…”