Earth-abundant Metal Chalcogenide Materials for Photovoltaics: Cu2ZnSn(S,Se)4 and Cu2BaSn(S,Se)4

Cheng-Ying Chen^1,2,3*, Wei-Chao Chen^1,3, You-Syuan Ye¹

¹Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
²Center of Atomic Initiative for New Materials, National Taiwan University, Taipei, Taiwan
³Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 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 the hotovoltaic 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) and 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.
In this talk, I will share some of our recent progresses on CZTSSe and CBTS: (1) Interface engineering of CdS/CZTS(Se) is an important aspect of improving the performance of buffer/absorber heterojunction combination. It has been demonstrated that the crossover phenomenon due to the interface recombination can be drastically eliminated by interface modification. Here, we present a comprehensive study on the effects of soft-baking (SB) temperature on the junction properties and the corresponding optoelectronic and interface-structural properties; (2) we used vacuum process to synthesis the CBTSSe absorber 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.

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

Keywords: Earth-abundant elements, Metal chalcogenides, Non-toxic elements, Solar Cells, Photovoltaics