液晶有机半导体材料的合成及场效应晶体管研究

Organic thin film transistors (OTFTs) which have the advantages of low manufacturing costs and large area fabrication process are expected to be used as the key elements for realizing the next generation electronics, such as for exible and printed electronics. The design and synthesis of small molecule organic materials used as semiconductors in OTFT have increased signicantly in recent years because of their easily to synthesize in large quantities and have reliable device performance. Numerous eort on synthesis has been devoted to developing superior organic semiconductor materials with high charge carrier mobilities. However the design of new materials with higher mobilities, long-term device stability and high fluorescence properties for practical applications is a new challenge in this field. Recently, the liquid-crystalline materials have been considered as promising candidates for OTFTs. This is because of the liquid crystals can form well-ordered polycrystalline thin-film with large aligned domain on the base of the deposition from or the thermal annealing in LC phase. Iino and co-workers have reported a liquid crystalline material Ph-BTBT-10 with Sm E phase. This material was able to form a uniform and molecularly smooth polycrystalline thin film by using Sm E precursor thin films. The highest mobility of Ph-BTBT-10 based OTFTs was obtained up to 13.9 cm2V-1s-1. Recently, we also synthesis series novel p-type liquid crystal material for OTFT. OTFT fabricated under the crystalline Smectic G phase demonstrates the highest mobility near to 10 cm2V-1s-1. In this project, we intend to design novel n-type or bipolar liquid crystal semiconductor materials based on 1,4-bis(2-cyano-2-phenylethenyl)benzene (CN-DSB)to satisfy the technical requirements of high mobility and thermal stability for OTFT materials.

有机薄膜晶体管具有低生产成本和可大面积制造的优势，在柔性器件、智能卡及电子纸等领域将会有广泛的应用。因此，应用于OTFT的有机小分子半导体材料体研究引起了科研工作者的关注。然而，具有高迁移率、空气稳定性及荧光性能的有机半导体材料仍是这一领域的挑战。液晶小分子材料因具有很好的成膜性及可溶液加工等优势引起科研工作者的关注。日本科学家Iino等以液晶小分子材料作为场效应晶体管的有源层，获得了空气稳定性及热稳定性都很好且空穴迁移率超过10 cm2V-1s-1的薄膜器件。申请人在液晶小分子半导体及场效应晶体管方面也取得了一定的成果，合成了系列p型液晶小分子材料，并进行场效应晶体管研究，获得了接近10 cm2V-1s-1的薄膜迁移率。然而，高性能空气稳定的n型材料仍是这一领域的瓶颈。本项目拟以含氰基的二苯乙烯基苯为母核，合成具有n型或双极性性能的液晶小分子半导体材料，优化器件制备工艺.

有机半导体器件以其易加工、低成本等特性吸引了全世界学术界和产业界的目光。有机场效应晶体管在柔性器件、智能卡及电子纸等领域将会有广泛的应用。在半导体器件工艺优化的同时，如何获得迁移率高、空气稳定性好及具有良好的溶解性的有机半导体材料仍是这一领域的挑战。液晶(Liquid crystal, LC)是一种介于固体与液体之间、具有规则性分子排列的有机化合物。它除了兼有液体和晶体的某些性质如流动性、各向异性等外，还具有其独特的物理性质。液晶材料在特定的液晶相态下具有独特的分子排列方式。通过分子设计和独特的薄膜加工方式可获得具有接近单晶分子排列方式的半导体薄膜，从而获得高性能的有机场效应晶体管器件。. 项目团队为解决目前有机场效应晶体管器件的问题而开展，合成了系列液晶小分材料，研究了不同器件制备的衬底温度、退火温度，以及溶液旋涂温度与器件性能之间的关系，目前，薄膜器件的迁移率超过8cm2/Vs，对于非液晶半导体材料，我们开展了单晶器件的制备。同时，在项目的支持下，开展了液晶/非液晶半导体材料共混器件的制备以及功能性半导体器件的探索，为后续半导体材料的设计提供了参考与依据。