Electrodeposition mechanism of quaternary compounds Cu2ZnSnS4: Effect of the additives

Publication date: 1 January 2018
Source:Applied Surface Science, Volume 427, Part A
Author(s): Aiyue Tang, Zhilin Li, Feng Wang, Meiling Dou, Jingjun Liu, Jing Ji, Ye Song
The electrodeposition mechanism of pure phase Cu2ZnSnS4 (CZTS) thin film with subsequent annealing was investigated in detail. An electrolyte design principle of quaternary compounds was proposed. The complex ions of Cu(H2C6H5O7)⁺, Cu2(C6H5O7)⁺, Zn(C4H5O6)⁺, Sn(H2C6H5O7)⁺ and Sn2(C6H5O7)⁺, which influenced the reduction process and played important roles in co-deposition, were identified by UV spectra. Electrochemical studies indicated that trisodium citrate and tartaric acid could narrow the co-deposition potential range of the four elements to −0.8V to −1.2V (vs. SCE). The cause was the synergetic effect that trisodium citrate inhibited the reduction of Cu²⁺ and Sn²⁺ and tartaric acid promoted the reduction of Zn²⁺. The reduction of S2O3²⁻ was mainly attributed to the induction effect of the metallic ions, and the H⁺ dissociated from tartaric acid could also promote the cathode process of S2O3²⁻. The reaction mechanism could be summarized as the following steps: (I) Cu(H2C6H5O7)⁺, Cu2(C6H5O7)⁺→Cu, Sn(H2C6H5O7)⁺, Sn2(C6H5O7)⁺→Sn, Zn(C4H5O6)⁺→Zn; (II) the desorption of (H2C6H5O7)⁻ and (C6H5O7)⁻, and the reduction of S2O3²⁻ induced by metallic ions and H⁺. The mechanism studies provided a path of electrolyte design for multicomponent compounds.



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