Abstract

A highly conductive metallic gas that is quantum mechanically confined at a solid-state interface is an ideal platform to explore non-trivial electronic states that are otherwise inaccessible in bulk materials. Although two-dimensional electron gases have been realized in conventional semiconductor interfaces, examples of two-dimensional hole gases, the counterpart to the two-dimensional electron gas, are still limited. Here we report the observation of a two-dimensional hole gas in solution-processed organic semiconductors in conjunction with an electric double layer using ionic liquids. A molecularly flat single crystal of high-mobility organic semiconductors serves as a defect-free interface that facilitates two-dimensional confinement of high-density holes. A remarkably low sheet resistance of 6?kΩ and high hole-gas density of 1014?cm?2 result in a metal-insulator transition at ambient pressure. The measured degenerate holes in the organic semiconductors provide an opportunity to tailor low-dimensional electronic states using molecularly engineered heterointerfaces.

Article

Publication: 「Nature Materials」

Title: Two-dimensional hole gas in organic semiconductors

Author: Naotaka Kasuya, Junto Tsurumi, Toshihiro Okamoto, Shun Watanabe*, and Jun Takeya*

DOI: 10.1038/s41563-021-01074-4

URL: https://doi.org/10.1038/s41563-021-01074-4