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Effective Negative Diffusion of Singlet Excitons in Organic Semiconductors

[Image: see text] Using diffraction-limited ultrafast imaging techniques, we investigate the propagation of singlet and triplet excitons in single-crystal tetracene. Instead of an expected broadening, the distribution of singlet excitons narrows on a nanosecond time scale after photoexcitation. This...

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Detalles Bibliográficos
Autores principales: Berghuis, Anton Matthijs, Raziman, T. V., Halpin, Alexei, Wang, Shaojun, Curto, Alberto G., Rivas, Jaime Gómez
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7869104/
https://www.ncbi.nlm.nih.gov/pubmed/33507078
http://dx.doi.org/10.1021/acs.jpclett.0c03171
Descripción
Sumario:[Image: see text] Using diffraction-limited ultrafast imaging techniques, we investigate the propagation of singlet and triplet excitons in single-crystal tetracene. Instead of an expected broadening, the distribution of singlet excitons narrows on a nanosecond time scale after photoexcitation. This narrowing results in an effective negative diffusion in which singlet excitons migrate toward the high-density region, eventually leading to a singlet exciton distribution that is smaller than the laser excitation spot. Modeling the excited-state dynamics demonstrates that the origin of the anomalous diffusion is rooted in nonlinear triplet–triplet annihilation (TTA). We anticipate that this is a general phenomenon that can be used to study exciton diffusion and nonlinear TTA rates in semiconductors relevant for organic optoelectronics.