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Brightening of dark excitons in 2D perovskites

Optically inactive dark exciton states play an important role in light emission processes in semiconductors because they provide an efficient nonradiative recombination channel. Understanding the exciton fine structure in materials with potential applications in light-emitting devices is therefore c...

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Detalles Bibliográficos
Autores principales: Dyksik, Mateusz, Duim, Herman, Maude, Duncan K., Baranowski, Michal, Loi, Maria Antonietta, Plochocka, Paulina
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Association for the Advancement of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8580304/
https://www.ncbi.nlm.nih.gov/pubmed/34757785
http://dx.doi.org/10.1126/sciadv.abk0904
Descripción
Sumario:Optically inactive dark exciton states play an important role in light emission processes in semiconductors because they provide an efficient nonradiative recombination channel. Understanding the exciton fine structure in materials with potential applications in light-emitting devices is therefore critical. Here, we investigate the exciton fine structure in the family of two-dimensional (2D) perovskites (PEA)(2)SnI(4), (PEA)(2)PbI(4), and (PEA)(2)PbBr(4). In-plane magnetic field mixes the bright and dark exciton states, brightening the otherwise optically inactive dark exciton. The bright-dark splitting increases with increasing exciton binding energy. Hot photoluminescence is observed, indicative of a non-Boltzmann distribution of the bright-dark exciton populations. We attribute this to the phonon bottleneck, which results from the weak exciton–acoustic phonon coupling in soft 2D perovskites. Hot photoluminescence is responsible for the strong emission observed in these materials, despite the substantial bright-dark exciton splitting.