Electrochemical self-assembly of CuSCN-DAST hybrid thin films

Abstract

Nanostructured inorganic–organic hybrid thin films of copper(I) thiocyanate (CuSCN) and 4-(N,N-dimethylamino)-4′-(N′-methyl)stilbazolium tosylate (DAST) were electrochemically self-assembled by adding DAST into methanolic bath containing Cu2+ and SCN− ions. Loading of the stilbazolium organic chromophore (DAS+) increased linearly on increasing DAST concentration, accompanied with changes of the film morphology, crystallographic orientation of CuSCN and transition from β- to α-CuSCN. At low DAST concentrations, transport limited passive occlusion of DAS+ has been suggested with its diffusion coefficient of 1.25 × 10−6 cm2 s−1 in methanol at 298 K, while the loading receives kinetic limitation by the surface chemical reaction to yield definitive hybrid structures, resulting in unique “hair comb” shape β-CuSCN-DAST and “nano-platelets” shape α-CuSCN-DAST hybrid structures. Both the inorganic and organic components are interconnected and bi-continuous, as the loaded DAS+ could be totally extracted by dimethylacetamide to leave porous skeleton of crystalline CuSCN, making them highly interesting for device applications.