Room-temperature deposition of nanocrystalline CuSCN film by the modified successive ionic layer adsorption and reaction method

Nanocrystalline CuSCN films were deposited from the room-temperature (20–25 °C) aqueous solutions by the successive ionic layer adsorption and reaction (SILAR) method. The substrate rinsing procedure in SILAR was modified to realize the deposition of CuSCN at reasonable rate. The S2O32− (chelating reagent)–Cu2+ molar ratio in the precursor was increased from 1:1 to 3:1, to stabilize the precursor and improve the film quality. Effects of the [SCN−/Cu2+] molar ratio on the crystallinity, the morphology and optical properties were examined. Obtained CuSCN film deposited at the optimal condition exhibits obvious crystallinity, high purity, dense and uniform morphology with the crystallite size of 20–30 nm, optical transmittance of 50–70% at 400–800 nm, and band gap of 3.94 eV. The higher S2O32−–Cu2+ molar ratios can prevent the formation of precipitations in the precursor and the by-products (Cu(SCN)2 and Cu3(SO4)2(OH)2 · xH2O) in the film. The optimal SCN−–Cu2+ molar ratio of 4:1 has been found, at which the film exhibits better crystallinity, smaller crystallite size, and denser film structure.