Bilayer p-n heterojunctions are promising structures to construct ambipolar organic field-effect transistors (aOFETs) for organic integrated circuits. However, due to the lack of effective strategies for high-quality p-n heterojunctions with clear interfaces, the performance of aOFETs is commonly and substantially lower than that of their unipolar counterparts, which hinders the development of aOFETs toward practical applications. Herein, a one-step solution crystallization strategy was proposed for the preparation of high-quality bilayer p-n heterojunctions. A mixed solution of a p- and an n-type organic semiconductor was dropped on a liquid substrate, and vertical phase separation occurred spontaneously during crystallization to produce bilayer p-n heterojunctions composed of molecularly thin two-dimensional molecular crystals. Due to the clear interface of the bilayer p-n heterojunctions, the maximum mobility (average mobility) reached 1.96 cm² V⁻¹ s⁻¹ (1.12 cm² V⁻¹ s⁻¹) for holes and 1.27 cm² V⁻¹ s⁻¹ (0.61 cm² V⁻¹ s⁻¹) for electrons in ambient air. So far as we know, these values were the highest among double-channel aOFETs measured in ambient air. This work provides a simple yet efficient strategy to construct high-quality bilayer p-n heterojunctions, which lays a foundation for their application in high-performance optoelectronic devices.

中文翻译：

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由二维分子晶体组成的 pn 异质结，用于高性能双极有机场效应晶体管

双层 pn 异质结是构建用于有机集成电路的双极有机场效应晶体管 (aOFET) 的有前途的结构。然而，由于缺乏具有清晰界面的高质量 pn 异质结的有效策略，aOFETs 的性能通常明显低于其单极对应物的性能，这阻碍了 aOFETs 向实际应用的发展。在此，提出了一种用于制备高质量双层pn异质结的一步法溶液结晶策略。a p - 和n 的混合解型有机半导体滴在液体衬底上，结晶过程中自发发生垂直相分离，产生由分子薄的二维分子晶体组成的双层 pn 异质结。由于双层pn异质结的清晰界面，空穴的最大迁移率（平均迁移率）达到1.96 cm ²  V ^-1  s ^-1（1.12 cm ²  V ^-1  s ^-1）和1.27 cm ²  V ^-1  s ^{- 1} (0.61 cm ²  V ⁻¹  s ⁻¹) 对于环境空气中的电子。据我们所知，这些值是在环境空气中测量的双通道 aOFET 中最高的。这项工作为构建高质量的双层 pn 异质结提供了一种简单而有效的策略，为其在高性能光电器件中的应用奠定了基础。