First-principles Study of Exciton-polarons and Self-trapped Excitons
ORAL
Abstract
Broadband white-light emission in perovskites has recently attracted significant attention. While its microscopic origin remains debated, the formation of self-trapped excitons (STEs) provides a compelling explanation for the observed broadband emission, large Stokes shift, and high photoluminescence quantum yield (PLQY).
We develop a first-principles framework to compute exciton–polarons and STEs by solving a Dyson-like equation within many-body perturbation theory, using phonon and exciton properties from BSE and DFPT. The method is validated on LiF and SiO₂ and applied to Cs₂AgInCl₆.Our results identify the key phonon modes and lattice distortions driving STE formation. From the exciton–polaron band structure and self-trapping barriers, we extract the energy lowering and STE lifetimes, explaining the observed Stokes shift and transient optical response. This framework offers a predictive, first-principles approach for quantitatively studying STE formation and exciton–phonon interactions in complex materials.
We develop a first-principles framework to compute exciton–polarons and STEs by solving a Dyson-like equation within many-body perturbation theory, using phonon and exciton properties from BSE and DFPT. The method is validated on LiF and SiO₂ and applied to Cs₂AgInCl₆.Our results identify the key phonon modes and lattice distortions driving STE formation. From the exciton–polaron band structure and self-trapping barriers, we extract the energy lowering and STE lifetimes, explaining the observed Stokes shift and transient optical response. This framework offers a predictive, first-principles approach for quantitatively studying STE formation and exciton–phonon interactions in complex materials.
*This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Early Career Award No. DE-SC0021965.
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Presenters
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Srikrishnaa Vadivel
- Yale University