Effects of metal ion concentration on electrodeposited CuZnSn film and its application in kesterite Cu₂ZnSnS₄ solar cells

Abstract

In this work, the effects of the concentrations of Cu (II), Zn (II) and Sn (II) ions in electrolytic bath solution on the properties of electrochemically deposited CuZnSn (CZT) films were investigated. The study of the composition of the CZT film has shown that the metallic content (relative atomic ratio) in the film increased linearly with the increase of the metal ion concentration. It is the first time that the relationship of the compositions of the alloy phases in the co-electrodeposited CZT film with the concentration of metal ions was revealed. The results have confirmed that the formantion and content of Cu6Sn5 and Cu5Zn8 alloy phases in the film were directly controlled by the concentration of Cu (II). SEM measurements have shown that Sn (II) had significant impacts on the film morphology which became more porous as a result of the bigger nucleation size of tin. The changes of surface properties of the films was also confirmed by chronoamperometry characteristic (i -t) deposition curve. By optimization of the metal ions concentrations in the electrolyte solution, a copperpoor and zinc-rich kesterite Cu2ZnSnS4 (CZTS) film was synthesized by sulfurization of the deposited CZT film. The solar cell with the CZTS film showed an energy conversion efficiency of 2.15% under the illumination intensity of 100 mW cm -2 .

Roughness-Controlled Cu2ZnSn(S,Se)4 Thin-Film Solar Cells with Reduced Charge Recombination

“…It should be noted that the new Cu–Sn alloy with higher Sn contents forms sparse and large deposits, which is consistent with literature reporting out-growth or dendritic growth of Sn-rich alloys. − The elemental composition of the CZT precursor film deposited for about 60 s (total deposition charge of 800 mC) clearly shows that the large deposits are consisting of the relatively Sn-rich Cu–Sn alloy (Figure b). The sparse and large nuclei work as seeds for the deposition, leading to the nonuniform morphology of the CZT precursor film.…”

Fabrication of CZTS Films through a Combined Electrodeposition and Solution Process: An Experimental and First‐Principles Study

“…Regarding CuÀ Sn binary phases, Cu 6 Sn 5 is widely observed in electrolytic CZTS fabrication, especially when Cu is electroplated along with Sn. [11,[55][56][57][58][59][60] This is because although the ΔG f °of Cu 3 Sn (i. e., À 7.78 kJ/mol at 250 °C) is slightly lower than that of Cu 6 Sn 5 (i. e., À 7.42 kJ/mol at 250 °C), Cu 6 Sn 5 is the first intermetallic compound that forms in a Cu-Sn interface as explained previously. [61][62][63][64] On the other hand, we observed diffraction peaks of Cu 3 Sn as shown in Figure 3.…”

Single-step electrodeposition of CZTS thin film: Influence of complexing agent concentration

“…The CZTS thin films has been fabricated by variety of vacuum and non-vacuum techniques such as atom beam sputtering, [10] hybrid sputtering, [11] RF magnetron sputtering, [12] , thermal evaporation, [13] pulsed laser deposition, [14,15] sulfurization of electron-beam-evaporated precursors, [16] spray pyrolysis, [17,18] nano-particle ink printing, [19] hydrazine-based approaches [20,21] sol-gel method, [22][23][24][25] and electrodeposition. [26,27] Electrodeposition is a low-cost technique used widely to synthesize various semiconductor thin films. [28] The fabrication of CZTS thin films by single-step electrodeposition is more challenging than the stacked elemental layer approach due to different reduction potentials of the metal ions species in the electrolyte.…”