Excitonic switching across a Z 2 topological phase transition: From Mott-Wannier to Frenkel excitons in organic materials

Controllable topological phase transitions in low dimensional materials allows for unconventional optical selection rules and exciton series. We show that the broad mixing of single-particle contributions to the exciton states occurring across a Z2 phase transition in 1D polyacene polymers leads to...

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Bibliographic Details
Published in:Physical review. B 2022-10, Vol.106 (15), Article 155122
Main Authors: Romanin, D., Calandra, M., Chin, A. W.
Format: Article
Language:English
Subjects:
Chemical Sciences
Condensed Matter
Mesoscopic Systems and Quantum Hall Effect
Physics
Polymers
Quantum Physics
Soft Condensed Matter
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Summary:Controllable topological phase transitions in low dimensional materials allows for unconventional optical selection rules and exciton series. We show that the broad mixing of single-particle contributions to the exciton states occurring across a Z2 phase transition in 1D polyacene polymers leads to an extreme tunability of optical properties, with exciton dispersions ranging from giganticbandwidth (≈ 1.5 eV) to practically zero. The acene length transversal to the periodic axis controls the exciton localization, allowing for a cross-over from Mott-Wannier to Frenkel-like excitons andlarge changes in optical gaps, singlet-triplet splittings and the orbital structure of the real-space exciton states. Our work opens appealing perspectives for the design of novel optolectronic devices.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.106.155122