Spontaneous Charge Carrier Localization in Extended One-Dimensional Systems

Vojtěch Vlček*, Helen R. Eisenberg, Gerd Steinle-Neumann, Daniel Neuhauser, Eran Rabani, Roi Baer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Charge carrier localization in extended atomic systems has been described previously as being driven by disorder, point defects, or distortions of the ionic lattice. Here we show for the first time by means of first-principles computations that charge carriers can spontaneously localize due to a purely electronic effect in otherwise perfectly ordered structures. Optimally tuned range-separated density functional theory and many-body perturbation calculations within the GW approximation reveal that in trans-polyacetylene and polythiophene the hole density localizes on a length scale of several nanometers. This is due to exchange-induced translational symmetry breaking of the charge density. Ionization potentials, optical absorption peaks, excitonic binding energies, and the optimally tuned range parameter itself all become independent of polymer length as it exceeds the critical localization length. Moreover, we find that lattice disorder and the formation of a polaron result from the charge localization in contrast to the traditional view that lattice distortions precede charge localization. Our results can explain experimental findings that polarons in conjugated polymers form instantaneously after exposure to ultrafast light pulses.

Original languageAmerican English
Article number186401
JournalPhysical Review Letters
Volume116
Issue number18
DOIs
StatePublished - 2 May 2016

Bibliographical note

Publisher Copyright:
© 2016 American Physical Society.

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