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.

量子力学限制在固态界面的高导电金属气体是探索非平凡电子态的理想平台，而这些电子态在散装材料中是无法接近的。尽管二维电子气已经在传统的半导体界面中实现，但二维空穴气的例子，二维电子气的对应物，仍然是有限的。在这里，我们报告了溶液处理有机半导体中二维空穴气体与使用离子液体的双电层结合的观察结果。高迁移率有机半导体的分子扁平单晶可作为无缺陷界面，促进高密度空穴的二维限制。6 kΩ 的极低薄层电阻和 10 的高空穴气体密度¹⁴  cm ^-2导致在环境压力下的金属-绝缘体转变。有机半导体中测量的简并空穴为使用分子工程异质界面定制低维电子态提供了机会。