High Carrier Density and Metallic Conductivity in Poly(3-hexylthiophene) Achieved by Electrostatic Charge Injection

Autor: Matthew J. Panzer, C. D. Frisbie
Rok vydání: 2006
Předmět:
Zdroj: Advanced Functional Materials. 16:1051-1056
ISSN: 1616-3028
1616-301X
Popis: The use of electrostatic charge injection (i.e., the transverse field effect) to induce both very large two-dimensional hole densities (∼ 1015 charges cm–2) and metallic conductivities in poly(3-hexylthiophene) (P3HT) is reported. Films of P3HT are electrostatically gated by a solution-deposited polymer-electrolyte gate dielectric in a field-effect-transistor configuration. Exceptionally high hole field-effect mobilities (up to 0.7 cm2 V–1 s–1) are measured concurrently with large hole densities, resulting in an extremely large sheet conductance of 200 μS sq.–1. The large room-temperature conductivity of 1000 S cm–1 together with the very low measured activation energies (0.7–4 meV) suggest that the metal–insulator transition in P3HT is achieved. A maximum in sheet conductance versus charge density is also observed, which may result from near-filling of the valence band or from charge correlations that lower the carrier mobility. Importantly, the large hole densities in P3HT are achieved using capacitive coupling between the polymer-electrolyte gate dielectric and P3HT (i.e., the field effect) and not via chemical or electrochemical doping. Electrostatic control of carrier density up to 1015 charges cm–2 (∼ 1022 charges cm–3) opens opportunities to explore systematically the importance of charge-correlation effects on transport in conjugated polymers without the structural rearrangement associated with chemical or electrochemical doping.
Databáze: OpenAIRE
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