Monolayer molecular crystal field-effect transistors: advances and perspectives

To break the limitations of traditional molecular materials in electronic devices, especially in organic field-effect transistors (OFETs), developing monolayer molecular crystals (MMCs) with the ultimate thickness is crucial: (1) the ultra-thin thickness of MMCs could reduce the contact resistance (Rc) and result in high-efficiency charge carrier injection, which can improve device performance and facilitate the miniaturization and high-frequency application of OFETs; (2) the ordered molecular packing and uniform quality of MMCs would relieve the morphology complexity and varied interface quality of traditional semiconductors, thus guarantee better performance uniformity and a lower coefficient of variation; and (3) the direct exposure of conducting channels provides a neat platform to reveal the relationship between molecular packing structures and charge transport physics, etc. Thus, preparing MMCs and constructing MMC-based electronic devices has great potential for fundamental scientific research and stimulates the application of OFETs in organic circuits. This review summarizes the latest events in MMCs, including the preparation techniques, the performance of devices, charge transport mechanisms and their applications. Finally, the challenges and prospects of MMCs are provided. We hope this comprehensive summary of MMC-related studies will bring more intensive study in related fields. To break the limitations of traditional molecular materials in electronic devices, especially in organic field-effect transistors (OFETs), developing monolayer molecular crystals (MMCs) with the ultimate thickness is crucial.