On the preparation and analysis of Cu2ZnSnS4 absorber layer by electrodeposition method
Date Issued
2015
Date
2015
Author(s)
Chang, Carlos Wu
Abstract
Thin-film photovoltaic is currently the mainstream of the photovoltaic technology.In contrast to high efficiencies solar cells that are usually expensive, thin-film photovoltaic are appealing for its low cost and facile approach. Among them, CdTe and CIGS technologies dominate the thin-film market share nowadays. But due to toxicity of Cd and Se and availability issues of Te, In and Ga, the production of photovoltaic based on these absorber layer could be limited. Indeed, other absorber layers must be developed and Cu2ZnSnS4 has emerged as an advantageous choice for its toxic-free and material abundant property. Hence, this study focuses on the preparation of Cu2ZnSnS4 by electrochemical deposition of CuZnSn alloy and completed the formation reaction by sulfurization process. The experiment is divided into three parts. Initially, cyclic voltammetry of electrolytic bath containing copper, zinc, tin metal ions and sodium citrate is analyzed, with the purpose of obtaining good deposition potential range. The second part aims on the analysis of CuZnSn films eletrodeposited at −1.25V/SCE. Surface and cross-section morphology was analyzed by SEM, and phase identification analyzed by XRD and Raman spectra. The results suggested a dense and compact film was electrodeposited, but thickness and composition variation was observed in a determined direction of the film; details are discussed in this work. In the last part, sulfurization process of as-deposited CuZnSn alloy is investigated. Effects of annealing temperature, temperature ramping rate, and KCN treatment on sulfurization process are subsequently studied. The measurements used are SEM, XRD and Raman spectra. The results indicated that the formation of Cu2ZnSnS4 was evidenced at temperature above 500 °C. The films sulfurized under slow heating rate consisted of larger grains but presented poor adhesion. This could be partially improved by raising the ramping rate of sulfurization. And finally, the films with best conditions were treated with KCN treatment in order to remove copper sulfides from the surface, and Cu2ZnSnS4 thin films with relative homogeneous composition were achieved.
Subjects
Cu2ZnSnS4
sulfurization process
solar cell
thin film
electrodeposition
SDGs
Type
thesis
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