C-H直接芳基化聚合法,通过对聚合条件等进行筛选和优化,得到了三种性能良好且环境友好的双受体n型半导体聚合物 ,即聚(萘二亚胺-ALT-二硫苯基吡咯-二酮)(PNDI-DPP)、聚(萘二亚胺-ALT-二硫苯基异蓝)(PNDI-IID)和聚(萘二亚胺-ALT-二硫苯基苯并噻二唑)(PNDI-BT),其平均分子量~10到30kg mol-1,且具有较窄的多分散指数~2。
究了三种聚合物的光学、电化学和电荷传输性能。研究发现聚合物PNDI-BT与另外两种聚合物在薄膜中的聚集方式不同,PNDI-DPP和PNDI-IID采用J-聚集,而PNDI-BT则采用H-聚集的方式。三中聚合物均具有较深的LUMO(~-3.7eV)和HOMO能级(~-5.7到-5.8eV),这对制备单极性n型OTFTs很有利。此外还通过DFT计算进一步了解了三种聚合物链的电子结构和分子几何,并在柔性基底(PET)上制备了顶栅底接触OTFTs来评估三者的电荷传输特性。结果表明,在三种双受体聚合物中,具有中等Mn的PNDI-BT在单极n型有机晶体管中表现出高的电子迁移率,高可达0.6cm2 V−1 s−1,这主要得益于其相对平面的主链以及低未占据分子轨道较大的重叠等。
C-H direct arylation polymerization method, through screeningand optimizing the polymerization conditions, three kinds ofdouble-acceptor n-type semiconductor polymers with good performanceand environmental friendliness were obtained, namely, poly(naphthalene diimide ALT dithiophenyl pyrrole dione) (PNDI-DPP),poly (naphthalene diimide ALT dithiophenyl isoblue) (PNDI-IID) andpoly (naphthalene diimide ALT dithiophenyl benzothiadiazole)(PNDI-BT), with an average molecular weight of 10 to 30 kg mol-1,And has a narrow polydispersity index of 2.
The optical, electrochemical and charge transfer properties ofthe three polymers were investigated. It is found that theaggregation mode of polymer PNDI-BT is different from the other twopolymers in the film. PNDI-DPP and PNDI-IID adopt J-aggregation,while PNDI-BT adopts H-aggregation. The three polymers have deepLUMO (~-3.7eV) and HOMO energy levels (~-5.7 to -5.8 eV), which isvery beneficial to the preparation of unipolar n-type OTFTs. Inaddition, the electronic structure and molecular geometry of thethree polymer chains were further understood through DFTcalculations, and the top-grid and bottom-contact OTFTs wereprepared on flexible substrates (PET) to evaluate their chargetransfer characteristics. The results show that PNDI-BT with mediumMn has the highest electron mobility in the unipolar n-type organictransistor, up to 0.6 cm2 V − 1 s − 1, which is mainly due to itsrelatively flat main chain and the large overlap of the lowestunoccupied molecular orbital.