Tjhe, D.H. L.; Ren, X.; Jacobs, I.E.; D'Avino, G.; Mustafa, T.B. E.; Marsh, T.G.; Zhang, L.; Fu, Y.; Mansour, A.E.; Opitz, A.; Huang, Y.; Zhu, W.; Unal, A.H.; Hoek, S.; Lemaur, V.; Quarti, C.; He, Q.; Lee, J.-K.; McCulloch, I.; Heeney, M.; Koch, N.; Grey, C.P.; Beljonne, D.; Fratini, S.; Sirringhaus, H.: Non-equilibrium transport in polymer mixed ionic-electronic conductors at ultrahigh charge densities. Nature Materials 23 (2024), p. 1712–1719
10.1038/s41563-024-01953-6
Open Accesn Version
Abstract:
Conducting polymers are mixed ionic–electronic conductors that are emerging candidates for neuromorphic computing, bioelectronics and thermoelectrics. However, fundamental aspects of their many-body correlated electron–ion transport physics remain poorly understood. Here we show that in p-type organic electrochemical transistors it is possible to remove all of the electrons from the valence band and even access deeper bands without degradation. By adding a second, field-effect gate electrode, additional electrons or holes can be injected at set doping states. Under conditions where the counterions are unable to equilibrate in response to field-induced changes in the electronic carrier density, we observe surprising, non-equilibrium transport signatures that provide unique insights into the interaction-driven formation of a frozen, soft Coulomb gap in the density of states. Our work identifies new strategies for substantially enhancing the transport properties of conducting polymers by exploiting non-equilibrium states in the coupled system of electronic charges and counterions.