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Ultrafast Excited-State Localization in Cs2AgBiBr6 Double Perovskite

Wright, Adam D ; Buizza, Leonardo R. V ; Savill, Kimberley J ; Longo, Giulia ; Snaith, Henry J ; Johnston, Michael B ; Herz, Laura M

The journal of physical chemistry letters, 2021-04, Vol.12 (13), p.3352-3360 [Periódico revisado por pares]

American Chemical Society

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  • Título:
    Ultrafast Excited-State Localization in Cs2AgBiBr6 Double Perovskite
  • Autor: Wright, Adam D ; Buizza, Leonardo R. V ; Savill, Kimberley J ; Longo, Giulia ; Snaith, Henry J ; Johnston, Michael B ; Herz, Laura M
  • Assuntos: Letter ; Physical Insights into Energy Science
  • É parte de: The journal of physical chemistry letters, 2021-04, Vol.12 (13), p.3352-3360
  • Notas: ObjectType-Article-1
    SourceType-Scholarly Journals-1
    ObjectType-Feature-2
    content type line 23
  • Descrição: Cs2AgBiBr6 is a promising metal halide double perovskite offering the possibility of efficient photovoltaic devices based on lead-free materials. Here, we report on the evolution of photoexcited charge carriers in Cs2AgBiBr6 using a combination of temperature-dependent photoluminescence, absorption and optical pump–terahertz probe spectroscopy. We observe rapid decays in terahertz photoconductivity transients that reveal an ultrafast, barrier-free localization of free carriers on the time scale of 1.0 ps to an intrinsic small polaronic state. While the initially photogenerated delocalized charge carriers show bandlike transport, the self-trapped, small polaronic state exhibits temperature-activated mobilities, allowing the mobilities of both to still exceed 1 cm2 V–1 s–1 at room temperature. Self-trapped charge carriers subsequently diffuse to color centers, causing broad emission that is strongly red-shifted from a direct band edge whose band gap and associated exciton binding energy shrink with increasing temperature in a correlated manner. Overall, our observations suggest that strong electron–phonon coupling in this material induces rapid charge-carrier localization.
  • Editor: American Chemical Society
  • Idioma: Inglês

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