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Novel Absorption Feature due to Intrinsic Quantum Confinement in FAPbI<sub>3</sub>

ORAL

Abstract

In this study[1], I report the discovery of intrinsically-occurring nanostructures in FAPbI3, which exhibit quantum confinement effects manifested as an oscillatory absorption feature above the band gap. These features are present at room temperature but sharpen and become more apparent as the temperature is lowered. I demonstrate that the energetic spacings and temperature-dependence of the peaks vary in a manner consistent with quantum confinement intrinsically associated with the lattice of the material. I suggest the origin of this confinement to be nanodomains with an extent of approximately 10-20 nm. This interpretation is supported by correlating absorption spectra against ab initio calculations based on the bandstructure of FAPbI3 in the presence of infinite barriers, and simulations for superlattices with moderate barrier heights. I further explore ferroelectricity/ferroelasticity and delta-phase twin boundaries as two possible causes of these domains. Altogether, such absorption peaks present a novel and intriguing quantum electronic phenomenon in a nominally bulk semiconductor, offering intrinsic nanoscale optoelectronic properties without necessitating cumbersome additional processing steps.

[1] A. D. Wright et al., Nat. Mater. 2020.doi:10.1038/s41563-020-0774-9

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Presenters

  • Adam Wright

    Department of Physics, University of Oxford

Authors

  • Adam Wright

    Department of Physics, University of Oxford

  • George Volonakis

    Department of Materials, University of Oxford

  • Juliane Borchert

    Department of Physics, University of Oxford

  • Christopher Davies

    Department of Physics, University of Oxford

  • Feliciano Giustino

    Physics, University of Texas at Austin, University of Texas at Austin, Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Department of Physic, The University of Texas at Austin, Austin, Texas 78712, USA, Oden Institute for Computational Engineering and Sciences, Oden Institute, University of Texas at Austin, Department of Materials, University of Oxford, Department of Physics, University of Texas at Austin, ODEN Institute for Computational Engineering and Sciences, University of Texas at Austin

  • Michael B Johnston

    Department of Physics, University of Oxford

  • Laura Herz

    Department of Physics, University of Oxford