Exciton-phonon coupling and self-trapped exciton structure in a 1D metal halide hybrids
ORAL
Abstract
Low-dimensional organic-inorganic metal halide hybrids have emerged with remarkable optical and electronic properties with larger potential to withstand instability to heat and moisture. Our work is based on a lower dimensional perovskite, a 1D perovskite of formula C4N2H14PbBr4, consisting of Pb-Br chains separated by organic cations. Experiment showed a large Stokes shift (0.83 eV) after excitation at 360 nm, indicating that self-trapped excitons dominate the emission [Nat. Commun. 8, 14051 (2017), Small Struc. 4, 2200378 (2023)]. This emission is broadband, hinting at interesting photo-physics involving the self-trapped excitons. We investigate self-trapped excitons via our approach for excited state forces in the GW/Bethe Salpeter equation method with the BerkeleyGW code. We examine how excitons couple with phonon modes which we find to be consistent with the temperature dependent photoluminescence data. We relax using the excited state forces to identify the self-trapped exciton structure. We compare to previous literature with constrained DFT which do not incorporate excitonic effects. This simulation of the dynamics of the exciton self-trapping gives insight into the contribution to broadband emission.
* Merced nAnomaterials Center for Energy and Sensing, MERCED cluster at UC Merced and NERSC supercomputer at LBNL
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Presenters
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Rijan Karkee
UC Merced
Authors
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Rijan Karkee
UC Merced
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Rafael R Del Grande
University of California, Merced
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David A Strubbe
University of California, Merced