Current Photovoltaic Research

Korea Photovoltaic Society (한국태양광발전학회)
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Effect of Se Flux and Se Treatment on the Photovoltaic Performance of β-CIGS Solar Cells

  • Kim, Ji Hye (Dept. of Materials Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Cha, Eun Seok (Dept. of Materials Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Park, Byong Guk (Dept. of Materials Science and Engineering, Korea Advanced Institute of Science and Technology) ;
  • Ahn, Byung Tae (Dept. of Materials Science and Engineering, Korea Advanced Institute of Science and Technology)
  • Received : 2015.06.08
  • Accepted : 2015.06.11
  • Published : 2015.06.30
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Abstract

$Cu(In,Ga)_3Se_5$ (${\beta}-CIGS$) has a band gap of 1.35 eV which is an optimum value for high solar-energy conversion efficiency. However, ${\beta}-CIGS$ film was not well characterized yet due to lower efficiency compared to $Cu(In,Ga)Se_2$ (${\alpha}-CIGS$). In this work, ${\beta}-CIGS$ films were fabricated by a three-stage co-evaporation of elemental sources with various Se fluxes. As the Se flux increased, the crystallinity of ${\beta}-CIGS$ phase was improved from the analysis of Raman spectroscopy and a deep-level defect was reduced from the analysis of photoluminescence spectroscopy. A Se treatment of the ${\beta}-CIGS$ film at $200^{\circ}C$ increased Ga content and decreased Cu content at the surface of the film. With the Se treatment at $200^{\circ}C$, the cell efficiency was greatly improved for the CIGS films prepared with low Se flux due to the increase of short-circuit current and fill factor. It was found that the main reason of performance improvement was lower Cu content at the surface instead of higher Ga content.

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References

  1. P. Jackson, D. Hariskos, E. Lotter, S. Paetel, R. Wuerz, R. Menner, W. Wischmann, M. Powalla, "New world record efficiency for $Cu(In,Ga)Se_2$ thin-film solar cells beyond 20%", Prog. Photovolt: Res. Appl., 19, 894-897, 2011. https://doi.org/10.1002/pip.1078
  2. L. Yu and A. Zunger, Phys. Rev. Lett., 108, 068701, 2012. https://doi.org/10.1103/PhysRevLett.108.068701
  3. M. Gloeckler, J. R. Sites, "Efficiency limitations for wideband- gap chalcopyrite solar cells", Thin Solid Films, 480-481, 241-245, 2005. https://doi.org/10.1016/j.tsf.2004.11.018
  4. T. Negami, N. Kohara, M. Nishitani, T. Wada, "Preparation of ordered vacancy chalcopyrite-type $CuIn_3Se_5$ thin films", Jpn. J. Appl. Phys., 33, L1251 - L1253, 1994. https://doi.org/10.1143/JJAP.33.L1251
  5. D. Y. Lee, J. J. Yun, K. H. Yoon, B. T. Ahn, "Characterization of Cu-poor surface on Cu-rich CuInSe2 film prepared by evaporating binary selenide compounds and its effect on solar efficiency", Thin Solid Films, 410, 171-176, 2002. https://doi.org/10.1016/S0040-6090(02)00249-3
  6. L. Larina, D. Shin, J. H. Kim, B. T. Ahn, Energy Environ. Sci., "Alignment of energy levels at the$ZnS/Cu(In,Ga)CuIn_3Se_5$ interface" 4, pp 3487-3493, 2011. https://doi.org/10.1039/c1ee01292d
  7. Y. M. Shin, C. S. Lee, D. H. Shin, H. S. Kwon, B. G. Park, B. T. Ahn, "Surface modification of CIGS film by annealing and its effect on the band structure and photovoltaic properties of CIGS solar cells", Curr. Appl. Phys. 15, 18-24 (2015). https://doi.org/10.1016/j.cap.2014.09.023
  8. T. Nakada, T. Mouri, Y. Okano, A. Kunioka, "$Cu(In,Ga)_3Se_5$- based thin film solar cells fabricated by a Na control technique", 14th EU-PVSEC, pp. 2143, 1997.
  9. K. H. Kim, K. H. Yoon, J. H. Yun, and B. T. Ahn, 'Effects of Se flux on the microstructure of $Cu(In,Ga)Se_2$ film deposited by a three-stage co-evaporation process', Electrochem. Solid-State Lett., 9, A382-A385 (2006). https://doi.org/10.1149/1.2208011
  10. J. H. Kim, Y. M. Shin, S. T. Kim, B. T. Ahn, "Fabrication of wide-bandgap ${\beta}-Cu(In,Ga)_3Se_5$ thin films and their application to solar cells", Current Photovoltaic Research, 1, 38 (2013).