Interface and bulk properties of Cu(In,Ga)Se2 solar cell with a cracker-ZnS buffer layer

Woo Jung Lee, Dae Hyung Cho, Jisu Yoo, Jengsu Yoo, Jae Hyung Wi, Won Seok Han, Yoonsung Nam, Yeonjin Yi, Soo Kyung Chang, Yong Duck Chung

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Abstract

Cu(In,Ga)Se2 (CIGS) solar cells were fabricated by varying the film thickness of the cracker-ZnS (c-ZnS) buffer layer from 0 nm to 20 nm, and performance was found to depend on c-ZnS film thickness. The best cell efficiency of approximately 8% was obtained from the CIGS solar cell with an 8 nm thick-c-ZnS buffer layer. To investigate the primary factor to determine the cell performance, we utilized the impedance spectroscopy (IS) reflecting interface qualities, and capacitance-voltage (CV) profiling sensitive to bulk properties. In IS results, an equivalent circuit model including the resistance and capacitance was proposed to interpret cell performance, and carrier lifetime was obtained in connection with recombination probability at p-n junction. In CV profiling, the carrier concentration in the CIGS bulk, the depletion width, and the charge distribution related to the defect states along the depth direction were evaluated. The formation mechanism of c-ZnS buffer layer is suggested by measuring the chemical states, which is closely associated with the IS and CV results. The depletion width substantially increased at c-ZnS film thickness more than 15 nm due to the diffusion of Zn atoms toward CIGS layer, resulting in negative influence on cell performance. From this study, we demonstrated that IS and CV profiling are complementary analysis tools for interpretation of the solar cell operation concerning the interface and bulk properties.

Original languageEnglish
Pages (from-to)405-410
Number of pages6
JournalCurrent Applied Physics
Volume18
Issue number4
DOIs
Publication statusPublished - 2018 Apr

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physics and Astronomy(all)

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    Lee, W. J., Cho, D. H., Yoo, J., Yoo, J., Wi, J. H., Han, W. S., Nam, Y., Yi, Y., Chang, S. K., & Chung, Y. D. (2018). Interface and bulk properties of Cu(In,Ga)Se2 solar cell with a cracker-ZnS buffer layer. Current Applied Physics, 18(4), 405-410. https://doi.org/10.1016/j.cap.2018.02.003