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Breakdown of Polarons in Conducting Polymers at Device Field Strengths
- Mahani, M. R., Mirsakiyeva, A., Delin, Anna
- The Journal of Physical Chemistry C 2017 v.121 no.19 pp. 10317-10324
- electric field, electronic equipment, engineering, models, physical chemistry, polymers
- Conducting polymers have become standard engineering materials used in many electronic devices. Despite this, there is a lack of understanding of the microscopic origin of the conducting properties, especially at realistic device field strengths. We present simulations of doped poly(p-phenylene) (PPP) using a Su–Schrieffer–Heeger (SSH) tight-binding model, with the electric field included in the Hamiltonian through a time-dependent vector potential via Peierls substitution of the phase factor. We find that polarons typically break down within less than a picosecond after the field has been switched on, already for electric fields as low as around 1.6 mV/Å. This is a field strength common in many flexible organic electronic devices. Our results challenge the relevance of the polaron as charge carrier in conducting polymers for a wide range of applications.