基于有机量子阱电荷空间分离效应的高性能有机场效应晶体管的研究

Organic field-effect transistors (OFETs) with both high mobility and high carrier density are of critical importance in applications such as flexible drivers. Traditional OFETs are based on individual organic semiconductor, it is challenging to obtain both high mobility and high carrier density (the former requires highly-pure organic semiconductor, while the latter requires doping). Here, we propose the strategy of OFETs with quantum wells (QWs, xy plane) as the channels (QW-OFETs). The barrier layer in the QWs donates electrons and forms a depletion region, concurrently the potential layer accepts electrons and forms an electron-accumulation region with high carrier density. Moreover, the potential layer as the channel are spatially separated from the electron-donating barrier layer, eliminating the effect of Coulomb scattering. Thus, by utilizing the spatial separation of charges carriers of the QWs, OFETs with both high mobility and high carrier density can be obtained. The relationship of energy level of organic semiconductors, the solid-state packing, the barrier height and width/well depth and width of the QWs and the transport properties of the QW-OFETs will be revealed. The strategy for the construction of QW-OFETs will be explored to obtain OFETs with both high mobility and high carrier density, laying the theoretical and practical foundations for future high-performance OFETs.

同时具有高载流子浓度和高载流子迁移率的有机场效应晶体管（OFET）在未来柔性驱动等领域有着十分关键的应用。传统有机场效应晶体管的沟道由一种有机半导体构成，高载流子浓度和高载流子迁移率难以兼得（前者要求掺杂，后者要求高纯半导体）。本项目提出以两种能级匹配的有机半导体构成的量子阱（QW）做OFET沟道的方案（QW-OFET）。量子阱中势垒层给出电子形成耗尽层，势阱层接受并累积电子形成高载流子浓度的沟道。此外，量子阱中势阱层沟道和势垒层离化施主在空间上分离，避免了传输过程中来自势垒层离化施主的库伦散射，可获得高迁移率。本项目将揭示有机半导体分子结构、固态堆积、量子阱垒宽/阱宽及阱深等因素与QW-OFET载流子传输性能的关系，基于QW-OFET结构获得同时具有高载流子浓度和高载流子迁移率的有机场效应晶体管，为未来高性能OFET的设计提供新的理论支持和实践基础。

有机场效应晶体管（OFET）在未来柔性驱动等领域有着十分关键的应用。然而有机半导体较低的迁移率大大制约了其实用化。本项目以单分子或数个分子层厚的二维分子晶体为结构基元构筑有机单晶异质结及有机量子阱结构，通过表面掺杂效应及量子阱空间电荷分离效应系统提高有机半导体的迁移率，推动其实用化进程。为了实现上述目标，我们做了如下研究：（1）提出了一种新型的“相分离”分子设计策略，为二维结晶分子设计提供指导；（2）发展界面结晶法，实现二维分子晶体层数可调生长，获得从块体到单分子层厚的有机半导体单晶；（3）发展二维分子晶体模板诱导法和一步结晶法，成功制备了数个分子层厚的高质量异质结，并基于异质结获得了高性能器件。本项目提出或发展的二维结晶分子设计策略、界面结晶法及一步结晶法提供了可靠的制备超薄单晶的方法，为研究二维限域条件下有机半导体的光电性能进而获得高性能器件和电路提供了新的材料体系。