Giant electron-phonon coupling and deep conduction band resonance in metal halide double perovskite

Julian A. Steele, Pascal Puech, Masoumeh Keshavarz, Ruoxi Yang, Subhasree Banerjee, Elke Debroye, Cheol Woong Kim, Haifeng Yuan, Nam Ho Heo, Johan Vanacken, Aron Walsh, Johan Hofkens, Maarten B.J. Roeffaers

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Abstract

The room-temperature charge carrier mobility and excitation-emission properties of metal halide perovskites are governed by their electronic band structures and intrinsic lattice phonon scattering mechanisms. Establishing how charge carriers interact within this scenario will have far-reaching consequences for developing high-efficiency materials for optoelectronic applications. Herein we evaluate the charge carrier scattering properties and conduction band environment of the double perovskite Cs2AgBiBr6 via a combinatorial approach; single crystal X-ray diffraction, optical excitation and temperature-dependent emission spectroscopy, resonant and nonresonant Raman scattering, further supported by first-principles calculations. We identify deep conduction band energy levels and that scattering from longitudinal optical phonons-via the Fröhlich interaction-dominates electron scattering at room temperature, manifesting within the nominally nonresonant Raman spectrum as multiphonon processes up to the fourth order. A Fröhlich coupling constant nearing 230 meV is inferred from a temperature-dependent emission line width analysis and is found to be extremely large compared to popular lead halide perovskites (between 40 and 60 meV), highlighting the fundamentally different nature of the two "single" and "double" perovskite materials branches.

Original languageEnglish
Pages (from-to)8081-8090
Number of pages10
JournalACS Nano
Volume12
Issue number8
DOIs
Publication statusPublished - 2018 Aug 28

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Steele, J. A., Puech, P., Keshavarz, M., Yang, R., Banerjee, S., Debroye, E., Kim, C. W., Yuan, H., Heo, N. H., Vanacken, J., Walsh, A., Hofkens, J., & Roeffaers, M. B. J. (2018). Giant electron-phonon coupling and deep conduction band resonance in metal halide double perovskite. ACS Nano, 12(8), 8081-8090. https://doi.org/10.1021/acsnano.8b02936