含二吲哚并（并二噻吩）结构单元共轭聚合物的合成及其光电性能研究

The design, synthesis, characterization of a series of novel polymer semiconductors based on diindolothieno[3,2-b]thiophene (DITT) will be undertaken in this project. The thermal properties, electrochemical properties and optical properties of these polymers prepared will investigated, and their charge transport properties in organic field effect transistors (OFETs) devices and photovoltaic properties in organic solar cells will also be exploided. Diindolothieno[3,2-b]thiophene unit consist of a fused-six-ring core, possessing a large conjugation system with 18π-electrons and 8 p-electrons.The characteristics of planarity and electron-richness make it possible to become a good donor monomer for semiconducting polymers. Low band-gap materials will be obtained when DITT polymerizes with electron-poor monomers (acceptors) such as benzothiodiazole (BT), diketopyrrolopyrrole (DPP), thienopyrrole-dione(TPD) and naphthalenetetracarboxy- lic acid diimide (NDI). These materials will have long-wavelength and strong absorbance in UV-Vis region, possibly exibiting good performance in organic solar cell devices. When DITT polymerizes with other donor monomers, a new type of materials with good carrier mobilities will be obtained, which will be ideal candidates for organic field effect transistors. To understand the correlation between material structure and device performance, different alkyl substituents (C6-C24) on DITT unit and a series co-monomers will be applied for polymer preparation, and these polymers will be measured on devices, to obtained the ideal polymer semiconductors with high mobilities in OFET and excellent power converssion efficiencies (PCEs).

设计并合成一类含新结构单元二吲哚并（并二噻吩）的共轭聚合物半导体材料；研究该类材料的热学、光学和电子学特性；测试这些新材料在有机场效应晶体管和有机太阳能电池器件中的性能;探索材料的光电性能与聚合物分子结构之间的关系，为开发性能良好的有机聚合物光电材料提供理论依据。二吲哚并（并二噻吩）结构单元具有18个π电子和8个P电子形成的稠环大共轭体系，富电子性及平面性的结构特征使其可能成为良好的电子供体，与电子受体（如苯并噻二唑）共聚将获得一类具有较低能带隙、在紫外-可见光区吸收波长范围宽且摩尔吸收系数大适宜用于制作有机太阳能器件的D-A型聚合物材料；与其它富电子单体共聚将获得载流子迁移率高的有机场效应晶体管材料。通过变换二吲哚并（并二噻吩）单体中的烷基取代基及对与其共聚的单体进行匹配优化，筛选出性能优异（载流子迁移率和光电转化率高）、稳定性好、器件易于加工的有机光电功能材料新品种。

共轭聚合物半导体材料已经被广泛应用于有机电子器件的制作，这些器件的制造成本低, 具有良好的柔软性，可大面积制造等优点，但其器件性能目前还无法与无机半导体器件相媲美。设计合成具有稳定性好、载流子迁移率高、易于加工的有机聚合物半导体材料对器件性能的提高至关重要。本项目研究以并二噻吩为原料，经与其它芳环体系的偶联反应，获得了一类新型的二吲哚并（并二噻吩）聚合物单体及二茚并二（并二噻吩）单体。二吲哚并（并二噻吩）单体及二茚并二（并二噻吩）单体经Suzuki偶联反应和Stille偶联反应，分别与缺电子的苯并噻二唑（BT）、氟代苯并噻二唑、吡咯并吡咯二酮（DPP）、萘四甲酰二亚胺（NDI）、富电子的噻吩、并二噻吩、并三噻吩等单体共聚，获得了一系列新型的聚合物半导体材料。这些聚合物材料在紫外-可见光区有较强吸收，易溶于有机溶剂，成膜性强，便于进行器件的加工。以这些聚合物作为活性层材料用于制备有机电子器件尤其是有机场效应晶体管器件时，器件性能良好。其中 四（十六烷基）二茚并二（并二噻吩）单体与苯并噻二唑形成的共聚物在有机场效应晶体管器件中的空穴迁移率高达6.6 cm2/Vs，电流开关比（Ion/Ioff）在100000 至1000000之间，是目前性能较理想的有机场效应晶体管材料之一。本研究同时探讨了烷基取代基结构对聚合物半导体材料性能的影响。含直链烷基取代基的聚合物材料较适合作为有机场效应晶体管材料；含支链烷基取代基的聚合物材料较适合于作为有机太阳能电池材料。代表性研究论文已发表在国际重要刊物Advanced Materials (Adv. Mater., 2016, 28: 3922–3927; 一区，影响因子21.95）和Journal of Material Chemistry（J. Mater. Chem. C, 2018, 6, 2004-2009；一区，影响因子5.98）上。