Band-like Transport of Charge Carriers in Oriented Two-Dimensional Conjugated Covalent Organic Frameworks
Band-like Transport of Charge Carriers in Oriented Two-Dimensional Conjugated Covalent Organic Frameworks
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DOI：
10.1021/acs.chemmater.1c03533
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发表时间：
2022-01-13
影响因子：
8.6
通讯作者：
Seki, Shu
中科院分区：
文献类型：
--
作者：
Ghosh, Samrat;Tsutsui, Yusuke;Seki, Shu
可调谐的拓扑结构和多孔网络使π共轭共价有机框架（COFs）成为一类新的有机半导体，用于光电，智能传感和催化应用。尽管一些COFs表现出高载流子迁移率的增强导电性，但电荷传输的性质和途径仍然难以捉摸。为了揭示传输机制，我们利用平面构建块开发了晶体pi共轭COFs，并生长了晶圆级自支撑薄膜，该薄膜可以转移到任何所需的衬底上。实验结果表明，COF薄膜具有高度的取向性和较高的面内电子导电性。电导率几乎不受温度的影响，具有14.3 meV的超低活化能，接近晶体内载流子的带状输运。COF薄膜在全可见光范围内表现出高的光电响应性，可作为柔性光电探测器器件。这项工作代表了对晶体pi共轭COF半导体中电荷输运机制和方向的深入研究，这表明它们作为多功能有机电子学的关键活性材料是可行的。
A tunable topology and a porous network make pi-conjugated covalent organic frameworks (COFs) a new class of organic semiconductors for optoelectronic, smart sensing, and catalytic applications. Although some of the COFs exhibit enhanced electric conductivity with a high charge carrier mobility, the nature and pathways of charge transport still remain elusive. In order to unveil the transport mechanism, herein, we have developed crystalline pi-conjugated COFs using planar building blocks, and a wafer-scale self-supporting thin film was grown, which could be transferred onto any of the desired substrates. The COF film was found to be highly oriented and exhibited a high in-plane electronic conductivity. The conductivity was almost independent of temperature with an ultra-low activation energy of 14.3 meV, approaching a band-like transport of charge carriers within the crystalline domains. The COF films also showed a high photoresponsivity in electronic conduction against a complete visible range, demonstrated as a flexible photodetector device. This work represents a thorough investigation of the mechanism and direction of charge transport in crystalline pi-conjugated COF semiconductors, which suggests their feasibility as key active materials in multifunctional organic electronics.