Electrodeposition of CdSe photoabsorber thin films in the presence of selected organic additives

Abstract

Photoabsorbing CdSe semiconductive thin films were prepared by cathodic electrodeposition onto titanium substrates from an acidic aqueous electrolytic bath, containing some selected, commercially available organic salts as additives, specifically monosodium l-glutamate and choline chloride. The products obtained were fully characterized with XRD and SEM–EDAX techniques and their photoelectrochemical behavior was studied using a photoelectrochemical cell (PEC). It is observed that the use of both additives leads to more uniform and in many cases to better crystallized deposits. All films, taken in the presence of the additives, exhibit some differences in their semiconductive behavior, in comparison to the pure CdSe ones. However, the addition of monosodium l-glutamate salt into the bath brought about a clear improvement in photoresponse of the deposits, whereas the use of the choline chloride salt clearly led to a deterioration of their photoconductivity. It is considered that the organic ions of the salts (l-glutamate anion and choline cation) are potentially adsorbed on the CdSe deposits, thus introducing crystal defects, which modify the electric properties of the final products.