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Electronic Excitations and Insulator-Metal Transition in Poly(3-hexylthiophene) Organic Field-Effect Transistors

N. Sai·Z. Q. Li·M. C. Martin·D. N. Basov·M. Di Ventra
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Abstract

We carry out a comprehensive theoretical and experimental study of charge injection in Poly(3-hexylthiophene) (P3HT) to determine the most likely scenario for metal-insulator transition in this system. We calculate the optical absorption frequencies corresponding to a polaron and a bipolaron lattice in P3HT. We also analyze the electronic excitations for three possible scenarios under which a first-- or a second--order metal--insulator transition can occur in doped P3HT. These theoretical scenarios are compared with data from infrared absorption spectroscopy on P3HT thin film field-effect transistors (FET). Our measurements and theoretical predictions suggest that charge-induced localized states in P3HT FETs are bipolarons and that the highest doping level achieved in our experiments approaches that required for a first-order metal--insulator transition.

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N. Sai, Z. Q. Li, M. C. Martin, D. N. Basov, M. Di Ventra. 2006-11-10. Electronic Excitations and Insulator-Metal Transition in Poly(3-hexylthiophene) Organic Field-Effect Transistors. https://doi.org/10.1103/physrevb.75.045307

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