Strong Coupling of Self-Trapped Excitons to Acoustic Phonons in Bismuth Perovskite $\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9}$
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2022
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| _version_ | 1866913171097255936 |
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| author | He, Xing Tailor, Naveen Kumar Satapathi, Soumitra Brgoch, Jakoah Yang, Ding-Shyue |
| author_facet | He, Xing Tailor, Naveen Kumar Satapathi, Soumitra Brgoch, Jakoah Yang, Ding-Shyue |
| contents | To assess the potential optoelectronic applications of metal-halide perovskites, it is critical to have a detailed understanding of the nature, strength, and dynamics of the interactions between carriers and the polar lattices. Here, we report the electronic and structural dynamics of bismuth-based perovskite $\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9}$ revealed by transient reflectivity and ultrafast electron diffraction. A cross-examination of these experimental results combined with theoretical analyses allows the identification of the major carrier-phonon coupling mechanism and the associated time scales. It is found that carriers photoinjected into $\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9}$ form self-trapped excitons on an ultrafast time scale. However, they retain most of their energy and their coupling to Fröhlich-type optical phonons is limited at early times. Instead, the long-lived excitons exert an electronic stress via deformation potential and develop a prominent, sustaining strain field as coherent acoustic phonons in 10 ps. From sub-ps to ns and beyond, a similar extent of the atomic displacements is found throughout the different stages of structural distortions, from limited local modulations to a coherent strain field to the Debye-Waller random atomic motions on longer times. The current results suggest the potential use of bismuth-based perovskites for applications other than photovoltaics to take advantage of carriers' stronger self-trapping and long lifetime. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2210_15165 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Strong Coupling of Self-Trapped Excitons to Acoustic Phonons in Bismuth Perovskite $\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9}$ He, Xing Tailor, Naveen Kumar Satapathi, Soumitra Brgoch, Jakoah Yang, Ding-Shyue Materials Science Chemical Physics To assess the potential optoelectronic applications of metal-halide perovskites, it is critical to have a detailed understanding of the nature, strength, and dynamics of the interactions between carriers and the polar lattices. Here, we report the electronic and structural dynamics of bismuth-based perovskite $\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9}$ revealed by transient reflectivity and ultrafast electron diffraction. A cross-examination of these experimental results combined with theoretical analyses allows the identification of the major carrier-phonon coupling mechanism and the associated time scales. It is found that carriers photoinjected into $\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9}$ form self-trapped excitons on an ultrafast time scale. However, they retain most of their energy and their coupling to Fröhlich-type optical phonons is limited at early times. Instead, the long-lived excitons exert an electronic stress via deformation potential and develop a prominent, sustaining strain field as coherent acoustic phonons in 10 ps. From sub-ps to ns and beyond, a similar extent of the atomic displacements is found throughout the different stages of structural distortions, from limited local modulations to a coherent strain field to the Debye-Waller random atomic motions on longer times. The current results suggest the potential use of bismuth-based perovskites for applications other than photovoltaics to take advantage of carriers' stronger self-trapping and long lifetime. |
| title | Strong Coupling of Self-Trapped Excitons to Acoustic Phonons in Bismuth Perovskite $\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9}$ |
| topic | Materials Science Chemical Physics |
| url | https://arxiv.org/abs/2210.15165 |