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arXiv · 2306.11352

Chemical Mapping of Excitons in Halide Double Perovskites

Raisa-Ioana Biega·Yinan Chen·Marina R. Filip·Linn Leppert
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Abstract

Halide double perovskites are an emerging class of semiconductors with tremendous chemical and electronic diversity. While their bandstructure features can be understood from frontier-orbital models, chemical intuition for optical excitations remains incomplete. Here, we use \textit{ab initio} many-body perturbation theory within the $GW$ and the Bethe-Salpeter Equation approach to calculate excited-state properties of a representative range of Cs$_2$BB$'$Cl$_6$ double perovskites. Our calculations reveal that double perovskites with different combinations of B and B$'$ cations display a broad variety of electronic bandstructures and dielectric properties, and form excitons with binding energies ranging over several orders of magnitude. We correlate these properties with the orbital-induced anisotropy of charge-carrier effective masses and the long-range behavior of the dielectric function, by comparing with the canonical conditions of the Wannier-Mott model. Furthermore, we derive chemically intuitive rules for predicting the nature of excitons in halide double perovskites using electronic structure information obtained from computationally inexpensive DFT calculations.

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Raisa-Ioana Biega, Yinan Chen, Marina R. Filip, Linn Leppert. 2023-06-20. Chemical Mapping of Excitons in Halide Double Perovskites. https://doi.org/10.1021/acs.nanolett.3c02285

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