Cd-Free Cu(In,Ga)(Se,S) 2 Thin-Film Solar Cell With Record Efficiency of 23.35%
2019; Institute of Electrical and Electronics Engineers; Volume: 9; Issue: 6 Linguagem: Inglês
10.1109/jphotov.2019.2937218
ISSN2156-3381
AutoresMotoshi Nakamura, Koji Yamaguchi, Yoshinori Kimoto, Y. Yasaki, Takuya Kato, H. Sugimoto,
Tópico(s)Copper-based nanomaterials and applications
ResumoIn this article, the excellent properties of state-of-the-art Cd-free Cu(In,Ga)(Se,S) 2 (CIGSSe) solar cells with Zn(O,S,OH) x /Zn 0.8 Mg 0.2 O double buffer layers, deposited by a combination of chemical bath deposition and atomic layer deposition techniques, are presented. By the replacement of conventional CdS buffer layers with this double buffer layer, the open-circuit voltage (V oc ) deficit of the devices could be significantly reduced, and V oc increased by approximately 15 mV. In addition, the fill factor and short-circuit current were also improved, increasing the device efficiency by approximately 0.5 absolute percent compared with devices with CdS buffers. The Cd-free double buffer layer improved the device efficiency regardless of the bandgap of the CIGSSe absorber. The minority carrier lifetime (τ) measured via time-resolved photoluminescence became longer, indicating that carrier recombination is mitigated using the double buffer layer. Based on the device parameters extracted by fitting the Suns-V oc characteristics to the double-diode model, the longer τ could be attributed to the decreased recombination rate in the space-charge region, rather than in the bulk and at the interface. The best performing cell was evaluated by a reliable third party, the National Institute of Advanced Industrial Science and Technology; this cell achieved a new world record efficiency of 23.35% for 1-cm 2 -sized thin-film polycrystalline solar cells. The device parameters of this cell are also discussed in this article.
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