Excitonic switching across a Z 2 topological phase transition: From Mott-Wannier to Frenkel excitons in organic materials - Sorbonne Université Access content directly
Journal Articles Physical Review B Year : 2022

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

Abstract

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 gigantic bandwidth (≈ 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 and large 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.
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Dates and versions

hal-03866084 , version 1 (22-11-2022)

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D. Romanin, M. Calandra, Alex W. Chin. Excitonic switching across a Z 2 topological phase transition: From Mott-Wannier to Frenkel excitons in organic materials. Physical Review B, 2022, 106 (15), pp.155122. ⟨10.1103/PhysRevB.106.155122⟩. ⟨hal-03866084⟩
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