| AVS 62nd International Symposium & Exhibition | |
| Energy Frontiers Focus Topic | Tuesday Sessions |
| Session EN-TuP |
| Session: | Energy Frontiers Poster Session |
| Presenter: | Alejandro Alvarez Barragan, University of California - Riverside |
| Authors: | A. Alvarez Barragan, University of California - Riverside S. Exarhos, University of California - Riverside J. Hernandez, University of California - Riverside L. Mangolini, University of California - Riverside |
| Correspondent: | Click to Email |
Nowadays, Cu2InxGa1-xSe4 (CIGS) and CdTe are the leading commercially available compounds in thin film photovoltaics technology. Nevertheless, the scarcity of In and Te, and the toxicity of Cd, are considerable threats that may hinder the production and increase the cost of these materials in the near future. Replacement of In, Ga, and Se in CIGS with Zn, Sn, and S yields the promising quaternary compound Cu2ZnSnS4 (CZTS). This material has a favorable direct band gap of 1.5 ev. Further, each of its constituent elements is earth abundant and non-toxic. These two attractive characteristics make it plausible to launch CZTS as the wave of the future in thin film PV. We now present the synthesis process of CZTS by electron beam evaporation and a subsequent sulfurization step1. A thin film of Zn, Cu, and Sn stacked layers was obtained upon localized heating of their respective metallic sources. The as-deposited layers were subsequently sulfurized under a vacuum inside a sealed quartz tube at temperatures ranging from 500°C to 600°C. One of the main difficulties that has been reported for CZTS synthesis is the stoichiometric control of the material. Secondary, unwanted phases such as CuS, SnS2, ZnS, and Cu2SnS3 may nucleate if the initial atomic percentage of the layers or the sulfurization parameters are off a small window in which CZTS can be produced2,3. Extreme care was taken to prevent this issue. Characterization techniques such as Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), and Raman Spectroscopy were heavily employed to confirm the presence of CZTS crystals. We are also presenting preliminary results regarding the synthesis of a Cu2ZnSn1-xSixS4 structure. To the best of our knowledge, synthesis of this compound by the E-beam evaporation and sulfurization process is yet to be reported. Previous theoretical and experimental data regarding its wide band gap add up to the interest of engineering this material for optoelectronic applications4.
1. Cheng, a.-J. et al. Imaging and phase identification of Cu2ZnSnS4 thin films using confocal Raman spectroscopy. J. Vac. Sci. Technol. A Vacuum, Surfaces, Film.29, 051203 (2011).
2. Nagoya, A., Asahi, R., Wahl, R. & Kresse, G. Defect formation and phase stability of Cu2ZnSnS4 photovoltaic material. Phys. Rev. B81, 113202 (2010).
3. Polizzotti, A., Repins, I. L., Noufi, R., Wei, S.-H. & Mitzi, D. B. The state and future prospects of kesterite photovoltaics. Energy Environ. Sci.6, 3171 (2013).
4. Nakamura, S., Maeda, T. & Wada, T. Phase Stability and Electronic Structure of In-Free Photovoltaic Materials: Cu2ZnSiSe4 , Cu2ZnGeSe4 , and Cu2ZnSnSe4. Jpn. J. Appl. Phys.49, 121203 (2010).