Defect induced absorption in mixed composition perovskite thin films and solar cells

ORAL

Abstract

Device performance, namely, current density (Jsc), open circuit voltage (Voc), fill factor (FF), and efficiency of mixed perovskite (ABX3: A=MA, FA, Cs; B=Pb, Sn; X=I, Br, Cl) thin film solar cells vary with the composition. The major parameters affecting the device performance with varying compositions are crystal structure, phase stability, optical properties, and defect states of the absorber material. Here, we use spectroscopic ellipsometry and photothermal deflection spectroscopy to study to the near-bandgap optical response in terms of the complex refractive index (N = n + ik) of mixed composition perovskite thin films. Sub-bandgap absorption manifests as somewhat well-defined features and Urbach tails below the band gap. Solar cell device performance parameters including Voc, FF, and efficiency as well as external quantum efficiency (EQE) are correlated with the Urbach energies and presence of defect states.

*University of Toledo start-up funds, Ohio Department of Development (ODOD), Ohio Research Scholar Program (Northwest Ohio Innovators in Thin Film Photovoltaics, Grant No. TECH 09-025)

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Presenters

  • Biwas Subedi

    • University of Toledo

Authors

  • Biwas Subedi

    • University of Toledo

  • Chongwen Li

    • University of Toledo

  • Lei Guan

    • University of Toledo

  • Yue Yu

    • University of Toledo

  • Max Junda

    • Wright Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH, 43606, USA
    • University of Toledo
    • The University of Toledo

  • Kiran Ghimire

    • Wright Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH, 43606, USA
    • University of Toledo

  • Prakash Uprety

    • University of Toledo

  • Yanfa Yan

    • The University of Toledo
    • Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo
    • Wright Ctr for Photovoltaics Innovation and Commercialization, Sch. for Solar and Adv. Energy, Dept of Physics and Astronomy, Univ of Toledo
    • Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA.

  • Nikolas Podraza

    • The University of Toledo
    • Univ of Toledo
    • University of Toledo