Preparation and mechanism of CuSCN film by electrodeposition in aqueous solution

A stable aqueous electrolyte solution containing Cu(II) cations and (SCN) anions was prepared by adding EDTA(ethylenediamine tetraacetic acid disodium salt, C(10)H(14)N(2)O(8)Na(2)(.)2H(2)O) to chelate with COD cations. CuSCN films were electrodeposited on transparent ITO conducting substrates from as-prepared electrolyte solution. Deposition mechanisms of CuSCN at varied temperatures have been studied. The results indicate that electron quantum tunnel through CuSCN film plays a role and the dense thin film with nanocrystals was obtained at or below room temperature. However, at higher temperature, a thermally activated process was involved and a thick film was obtained. It has been calculated that the activation energy of the growth for crystals is 0.5 eV. XPS pattern shows that the electrodeposited film is (SCN) in stoichiometric excess, indicating a p-type film. As-prepared CuSCN film was with high transmittance (>= 85%) in the visible optical range and the direct transition band gap was 3.7 eV.