The synthesis and characterization of four ethylene-bridged bisisoindigo (NCCN and NNNN)-based conjugated polymers are reported. In these polymers, 2,2′-bithiophene or (E)-1,2-di(thiophen-2-yl)ethene (DTE) is used as the electron donor. Compared to NCCN, NNNN has two additional sp²-nitrogen atoms adjacent to its vinyl group. The sp²-nitrogen atoms endow the two NNNN-based polymers PNNNN-BT and PNNNN-DTE with not only improved backbone planarity due to the formation of intramolecular five-ring intramolecular CH⋯N hydrogen bonds, but also slightly lowered frontier orbital energy levels. Combined with the more rigid backbone of DTE, PNNNN-DTE showed the highest electron mobility (μ_e) of 1.64 cm² V⁻¹ s⁻¹ in 1,2-dichlorobenzene (DCB)-processed ambipolar field-effect transistors and even a slightly increased μ_e in its DCB/1-chloronaphthalene (with v/v of 99.2/0.8) bi-component solvent-processed ones. Microstructural analyses indicated that the PNNNN-DTE thin films have more ordered and denser molecular packing, which is well in accordance with the change tendency of the electron mobility of these bisisoindigo-based conjugated polymers.

中文翻译：

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乙烯桥联双异靛蓝共轭聚合物：分子内CH⋯N氢键的影响


报道了四种乙烯桥联双异靛蓝（ NCCN和NNNN ）基共轭聚合物的合成和表征。在这些聚合物中，2,2'-联噻吩或( E )-1,2-二(噻吩-2-基)乙烯(DTE)用作电子给体。与NCCN相比， NNNN在其乙烯基附近有两个额外的 sp ² -氮原子。 sp ² -氮原子赋予两种NNNN基聚合物PNNNN-BT和PNNNN-DTE，不仅由于分子内五环分子内CH ⋯ N氢键的形成而改善了主链平面度，而且还略微降低了前沿轨道能级。结合 DTE 更刚性的骨架， PNNNN-DTE在 1,2-二氯苯 (DCB) 处理的双极场效应晶体管中表现出最高的电子迁移率 ( μ _e ) 1.64 cm ² V ^-1 s ^-1 ，甚至DCB/1-氯萘（v/v 为 99.2/0.8）双组分溶剂加工产品的μ _e略有增加。微观结构分析表明， PNNNN-DTE薄膜具有更有序、更致密的分子堆积，这与这些双异靛蓝基共轭聚合物的电子迁移率变化趋势非常一致。