Published January 14, 2025 | Version v1
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Accurate and efficient computation of the fundamental bandgap of the vacancy-ordered double perovskite Cs₂TiBr₆

  • 1. Discipline of Physics, The University of Newcastle, Callaghan, New South Wales 2308, Australia
  • 2. Laboratory for Materials Simulations, Paul Scherrer Institut, 5232 Villigen, Switzerland, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
  • 3. National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
  • 4. Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales 2308, Australia

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Description

Metal halide perovskites (MHPs) demonstrate an exceptional combination of properties. Rapid progress has extended their application beyond solar cells, light-emitting diodes, photodetectors, and lasers to include memristors, artificial synapse devices, and pressure induced emission. In particular, the vacancy-ordered double perovskite Cs₂TiBr₆ has been identified as a promising material. The effective characterization of MHPs requires accurate and efficient methods for the calculation of electronic structure. Koopmans compliant (KC) functionals are an accurate and computationally efficient alternative to many-body perturbation theory using the GW approximation but have yet only been validated on a small number of simple materials. In this work, KC functionals were applied to the more complex case of Cs₂TiBr₆ and gave a zero-temperature fundamental gap of 4.28 eV, in close agreement with the value of 4.44 eV obtained using the accurate, but more computationally expensive, evGW₀ approach. The temperature-dependent renormalization of the bandgap has also been investigated and found to be significant. Agreement with the experimental optical bandgaps of 1.76–2.0 eV would also require the inclusion of exciton binding energy.

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References

Journal reference (Paper where the data is discussed)
J. E. Ingall, E. Linscott, N. Colonna, A. J. Page, V. J. Keast, The Journal of Physical Chemistry C, 128, 9217−9228 (2024), doi: 10.1021/acs.jpcc.3c07957

Preprint (accepted, open-access manuscript version of the published article)
J. E. Ingall, E. Linscott, N. Colonna, A. J. Page, V. J. Keast, Digital Object Repository at PSI