Optimization of the nucleation-site density for the electrodeposition of cadmium sulfide on indium-tin-oxide

Abstract

Cadmium sulfide (CdS) is a preferred heterojunction partner for a number of chalcogenide-based solar cells. In view of this, interest has grown in the use of solution-based deposition techniques as an alternative route for the preparation of uniform ultrathin films of CdS. However, the quality of the electrodeposited CdS films on indium-tin oxide (ITO) remains far from optimal. This is because the ITO surface is electrochemically heterogeneous due to the presence of indium oxide; nucleation and further electrodeposition of CdS does not transpire on the oxided sites. Hence, only coarse-grained coatings, instead of homogeneous ultrathin films, are generated at un-pretreated ITO surfaces. In the present study, a mitigation of the amount of interfacial In oxide was attempted in order to increase the nucleation-site (indium-metal site) density. The procedure consisted of two steps: (i) Mild electrochemical reduction of the ITO to convert surface In(III) to In(0), followed by (ii) surface-limited redox replacement (SLRR) of In(0) by Cu via an aqueous solution of Cu 2+. This procedure resulted in the formation of a high density of oxide-free Cu on which CdS nuclei would form; the thickness was such that optical transparency was largely undiminished. A tenfold increase in CdS site density was observed, and that permitted the epitaxial growth of a second semiconductor, CdTe, atop the CdS film. The influences of applied potential and deposition time on nucleation-site sizes and densities were also studied.

Differentiating electrochemically active regions of indium tin oxide electrodes for hydrogen evolution and reductive decomposition reactions. An in situ optical microscopy approach

“…ITO is usually considered as an inert substrate. However, surface processes such as coating reconstruction, nanoscale defects formation (such as NPs) have been described [48] and are usually detected by ex situ SEM imaging. We propose herein to probe operando the reduction behavior of ITO coating using IRM monitoring during cyclic voltammetry experiments.…”

Annealing effect on cds nanowalls grown by chemical bath deposition on glass substrate

“…Cd based thin films have lately attracted great interest from the research community, with solar cells and other optoelectronic applications, and are used in the manufacture of solar cells due to the low band gap. CdS semiconductor thin films are obtained by various methods such as chemical deposition [10][11][12][13][14][15], electrodeposition [16], thermal evaporation [17], RF Magnetron sputtering [18], chemical spray pyrolysis [19]. Different CdS semiconductor morphologies have been prepared using various methods, including nanorods [20], flower-like nanorings [21], conifer-like [22], cauliflower-like microspheres [23], nanowires [24], flakes [25], and flowers [26].…”