Earth-abundant Metal Chalcogenide / Chalcogenide Semiconductors for Solar Energy: Cu2ZnSn(S,Se)4, Cu2BaSn(S,Se)4 and Selenium (Se)

Cheng-Ying Chen^1,2*

¹Department of Materials Engineering, Ming Chi University of Technology, New Taipei City, Taiwan
²Center for Plasma and Thin Film Technologies (CPTFT), Ming Chi University of Technology, New Taipei City, Taiwan

* Presenter:Cheng-Ying Chen, email:chen.chengying.cyc@gmail.com

The development of renewable energy is a trend in the world. And developing thin-film solar cells, which utilize photovoltaic effect to convert light energy into electrical energy, will play a key role in the global trend. Chalcogenide based thin-film photovoltaics such as CdTe and Cu(In,Ga)Se2 (CIGSe) have achieved remarkable over 20% power conversion efficiency (PCE). These thin-film materials have wide spectral response ranges and high absorption coefficients, so they are sensitive to weak light. However, the toxicity of cadmium (Cd), and the scarcity of indium (In) and tellurium (Te) may restrict the production capacity for a growing worldwide power consumption (~terawatt). Therefore, the development of low-cost, earth-abundant thin-film solar cells have attracted a lot of attention. the new generation metal chalcogenides: Cu2ZnSn(Se,S)4 (CZTSSe), Cu2BaSn(S,Se)4 (CBTS) will be two of the most potential alternative photovoltaic energy materials due to its abundant, non-toxic elements and providing desirable optoelectronic properties, similar to CIGSSe. Beside, single-element Selenium (Se) thin-film semiconductor also could be potential alternative solar energy materials.
In this talk, I will share some of our recent progresses on CZTSSe, CBTS and Se: (1) We tried to establish the correlation between the electronic structures near grain boundaries and photocarrier separations in this class of metal chalcogenide PVs. A significantly improved understanding of the electronic structures will eventually make technological breakthrough possible in this CZTSSe-like based materials in the near future. (2) the CBTSSe absorbers were prepared by the vacuum process and performed Raman, X-ray diffraction (XRD), photoluminescence (PL) measurements as the tools to understand the quality and the information of phase identification. Based on the results, the two-step prepared CBTSSe absorbers with tunable bandgap has been successfully demonstrated. (3) the single-element Selenium (Se) photovoltaic thin-films were deposited by the thermal evaporation and post-annealing. In addition, the material/phase qualities were characterized by Raman and PL.

References
[1] W.C. Chen, C.Y. Chen, V. Tunuguntla, S.H. Lu, C. Su, C.H. Lee, K.H. Chen and L.C. Chen, Nano Energy, 2016, 30, 762-770
[2] C.Y. Chen, B. S. Aprillia, W.C. Chen, Y.C. Teng, C.Y. Chiu, R.S. Chen, J.S. Hwang, K.H. Chen, and L. C. Chen, Nano Energy, 2018, 51, 597-603
[3] W.C. Chen, C.Y. Chen, Y.R. Lin, J.K. Chang, C.H. Chen, Y.P. Chiu, C.I Wu, K.H. Chen, and L.C. Chen, Materials Today Energy, 2019, 13, 256-266
[4] F. S. S. Chien, A. Herawati, M. Y. He, C. Y. Huang, C. Y. Chen, ACS Applied Electronic Materials, 2020, 2, 796-801
[5] 陳政營(C.Y.Chen), 大地豐富的金屬硫族化合物光伏電池：銅鋅錫硫（CZTS）, 化學 ； 77卷3期， P213 – 220 (2019) DOI： 10.6623/chem.201909_77(3).009

Keywords: CZTSSe, Earth-abundant elements, Metal chalcogenides, Non-toxic elements, Solar cells