Current Photovoltaic Research

Korea Photovoltaic Society (한국태양광발전학회)
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Bandgap Engineering in CZTSSe Thin Films via Controlling S/(S+Se) Ratio

  • Vijay C. Karade (Department of Energy Engineering, Korea Institute of Energy Technology (KENTECH)) ;
  • Jun Sung Jang (Optoelectronics Convergence Research Center and Department of Materials Science and Engineering, Chonnam National University) ;
  • Kuldeep Singh, Gour (Surface Engineering Group, Advanced Materials & Processes Division, CSIR-National Metallurgical Laboratory) ;
  • Yeonwoo Park (Department of Energy Engineering, Korea Institute of Energy Technology (KENTECH)) ;
  • Hyeonwook, Park (Department of Hydrogen Energy, Korea Institute of Energy Technology (KENTECH)) ;
  • Jin Hyeok Kim (Optoelectronics Convergence Research Center and Department of Materials Science and Engineering, Chonnam National University) ;
  • Jae Ho Yun (Department of Energy Engineering, Korea Institute of Energy Technology (KENTECH))
  • Received : 2023.07.31
  • Accepted : 2023.08.30
  • Published : 2023.09.30
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Abstract

The earth-abundant element-based Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells (TFSCs) have attracted greater attention in the photovoltaic (PV) community due to their rapid development in device power conversion efficiency (PCE) >13%. In the present work, we demonstrated the fine-tuning of the bandgap in the CZTSSe TFSCs by altering the sulfur (S) to the selenium (Se) chalcogenide ratio. To achieve this, the CZTSSe absorber layers are fabricated with different S/(S+Se) ratios from 0.02 to 0.08 of their weight percentage. Further compositional, morphological, and optoelectronic properties are studied using various characterization techniques. It is observed that the change in the S/(S+Se) ratios has minimal impact on the overall Cu/(Zn+Sn) composition ratio. In contrast, the S and Se content within the CZTSSe absorber layer gets altered with a change in the S/(S+Se) ratio. It also influences the overall absorber quality and gets worse at higher S/(S+Se). Furthermore, the device performance evaluated for similar CZTSSe TFSCs showed a linear increase and decrease in the open circuit voltage (Voc) and short circuit current density (Jsc) of the device with an increasing S/(S+Se) ratio. The external quantum efficiency (EQE) measured also exhibited a linear blue shift in absorption edge, increasing the bandgap from 1.056 eV to 1.228 eV, respectively.

Keywords

Acknowledgement

This work was supported in part by the National Research Foundation of Korea (NRF) (grant no. 2023R1A2C2003612) and in part by the program of Phased development of carbon neutral technologies (grant no. 2022M3J1A1085374) through NRF, both funded by Ministry of Science and ICT (MSIT).

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