Stochastic Electrical Detection of Single Ion-Gated Semiconducting Polymers.

Semiconducting polymer chains constitute the building blocks for a wide range of electronic materials and devices. However, most of their electrical characteristics at single-molecule level have received little attention. Elucidating these properties could help understanding performance limits and enable new applications. Here we exploit coupled ionic-electronic charge transport to measure the quasi-one-dimensional electrical current through long single conjugated polymer chains as they form transient contacts with electrodes separated by ∼10 nm. Fluctuations between internal conformations of the individual polymers are resolved as abrupt, multi-level switches in the electrical current. This behavior is consistent with our theoretical simulations based on the worm-like-chain model for semi-flexible polymers. In addition to probing the intrinsic properties of single semiconducting polymer chains, our results provide an unprecedented window into the dynamics of random-coil polymers and enable the use of semiconducting polymers as electrical labels for single-molecule (bio)sensing assays. This article is protected by copyright. All rights reserved.