Photophysics of Two-Dimensional Perovskites—Learning from Metal Halide Substitution |
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Authors: | Simon Kahmann Herman Duim Hong-Hua Fang Mateusz Dyksik Sampson Adjokatse Martha Rivera Medina Matteo Pitaro Paulina Plochocka Maria A. Loi |
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Affiliation: | 1. Photophysics and OptoElectronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen, AG, 9747 The Netherlands;2. Laboratoire National des Champs Magnétiques Intenses, UPR 3228, CNRS-UGA-UPS-INSA, Toulouse, 31400 France |
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Abstract: | 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. |
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Keywords: | 2D perovskites defects excitons magneto-photoluminescence photophysics Ruddlesden-Popper phases |
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