Electrodeposition of Tin onto Zinc for the Electrochemical Synthesis of Zn/Sn/Cu Precursor Stack for CZTS-Based Photoconversion Devices

In this work, the synthesis of a Mo(sub)/Zn/Sn/Cu metallic stack through electrodeposition is achieved by using an ethylene-glycol-based solution designed to deposit Sn onto a Mo/Zn substrate. The displacement reaction with zinc is minimized through the formation of complexes with diethanolamine. A correlation between the electrochemical behavior of Sn(II) species and the reactivity of zinc upon immersion in the tin plating bath is shown. Morphological and compositional characterization is carried out on the Zn/Sn/Cu stack at the different synthesis steps. Reactive annealing is carried out to convert the metallic precursor into CZTS with a minor presence of secondary phases. The resulting CZTS/CdS/Pt photoelectrode shows a photocurrent density of −5.73 mA cm−2 at 0 V vs RHE under 1 sun (AM 1.5 G). This study demonstrates how the chemistry of the plating bath is crucial for the deposition of thin films onto reactive substrates, reducing the technological gap with vacuum-based deposition methods