Synthesis and characterization of electro-crystallized Cd-Sn-Se semiconductor films for application in non-aqueous photoelectrochemical solar cells

Abstract

In the present investigation, thin films of CdSnSe have been developed on transparent conducting oxide (TCO) coated glasses by electrolytic deposition. The controlled incorporation of Sn in the semiconducting layer have been achieved by varying the concentration of Sn2+ from 5 to 22 g/l of SnCl2 in the deposition bath. The semiconductor film grown on the glass substrate consisted of n-type CdSnSe semiconductor compounds (alloyed and/or mixed type) in the form of highly dispersed, spherically shaped polycrystallites as detected from X-ray diffraction (XRD) studies, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Their optoelectronic properties were determined by spectroscopic analysis and electrochemical measurements. The performance characteristics of a photoelectrochemical (PEC) cell fabricated with the prepared photoelectrode and ferrocene-ferricenium redox couple in dimethyl formamide were observed under dark and illuminated conditions. The prepared semiconductor films were electrochemically characterized through capacitance-voltage measurements. The film that was obtained from 10 g/l of Sn2+, in the bath, showed an optimum spectral sensitivity and corresponded to a film thickness of 0.65 mu m and stoichiometry of Cd:Sn:Se as 1:1:1. The pronounced PEC activity of this film compared to the others was attributed to the combined effect of space charge properties, electron-hole recombination processes and transfer of charges through the Helmholtz layer at the semiconductor-solution interface.