Photophysics of Two‐Dimensional Perovskites—Learning from Metal Halide Substitution

2D perovskites offers a rich playing field to explore exciton physics and they possess a great potential for a variety of opto‐electronic applications. Whilst their photophysics shows intricate interactions of excitons with the lattice, most reports have so far relied on single compound studies. Wit...

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Bibliographic Details
Published in:Advanced functional materials 2021-11, Vol.31 (46), p.n/a
Main Authors: Kahmann, Simon, Duim, Herman, Fang, Hong‐Hua, Dyksik, Mateusz, Adjokatse, Sampson, Rivera Medina, Martha, Pitaro, Matteo, Plochocka, Paulina, Loi, Maria A.
Format: Article
Language:English
Subjects:
2D perovskites
defects
Electron states
Excitons
Low temperature
magneto‐photoluminescence
Materials science
Metal halides
Perovskites
photophysics
Raman spectroscopy
Ruddlesden‐Popper phases
Spectrum analysis
Substitutes
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Summary:2D perovskites offers a rich playing field to explore exciton physics and they possess a great potential for a variety of opto‐electronic applications. Whilst their photophysics shows intricate interactions of excitons with the lattice, most reports have so far relied on single compound studies. With the exception of variations of the organic spacer cations, the effect of constituent substitution on the photophysics and the nature of emitting species, in particular, have remained largely under‐explored. Here PEA2PbBr4, PEA2PbI4, and PEA2SnI4 (where PEA stands for phenylethylammonoium) are studied through a variety of optical spectroscopy techniques to reveal a complex set of excitonic transitions at low temperature. Weak high‐energy features are attributed to vibronic transitions breaking Kasha's, for which the responsible phonons cannot be accessed through simple Raman spectroscopy. Bright peaks at lower energy are due to two distinct electronic states, of which the upper is a convolution of the free exciton and a localized dark state and the lower is attributed to recombination involving shallow defects. This study offers deeper insights into the photophysics of 2D perovskites through compositional substitution and highlights critical limits to the communities’ current understanding of processes in these compounds. The photophysics of 2D perovskites is studied upon variation of the constituent metal and halide anions. All compounds exhibit persistent luminescence of hot excitons that violate Kasha's rule and a complex set of low‐energy transitions involving defects.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.202103778