Role of Coulomb Blockade in Nonlinear Transport of Conducting Polymers.

Nonlinear I-V characteristics associated with Coulomb blockade (CB) in conducting polymers were systematically investigated. At low temperatures, a crossover from Ohmic to nonlinear behavior was observed, along with drastically enhanced noise in differential conductance right from the crossover. The fluctuation can be well explained by the Coulombic oscillation in the collective percolation system, where the charge transport is related to the Coulombic charging energy between crystalline domains. Furthermore, a distinct quantum conductance, the fingerprint of CB caused by the individual tunneling between crystalline grains, was observed in sub-100 nm devices, confirming a strong association between nonlinear I-V characteristics and Coulomb blockade effect. .