Due to their advantages of being low-cost and light weight, and having mechanical flexibility, great attention has been focused on π-conjugated organic semiconductors. Many high-performing materials have been developed in the past decade. However, constructing electron-deficient ladder-type conjugated systems is far more challenging than constructing electron-rich systems. We have successfully synthesized a series of larger and extended novel electron-deficient aza-isoindigos (AIID-12, FAIID-12, and AIID-14) with up to 14 rings. Terminal fluorine atoms and the fusion of an additional naphthalene ring are also introduced to compare the properties of the resulting compounds to those of phenyl aza-isoindigos. Compared with isoindigo, the absorption spectra of AIID-12, FAIID-12, and AIID-14 extend into the NIR region at 900 nm due to their extended conjugation systems. These fused aza-isoindigo conjugated systems exhibit excellent solubility, highly planar backbones, substantial crystallinity, tunable conjugation lengths, and optoelectrical properties. The more extensive conjugated system with higher highest occupied molecular orbital (HOMO) and unchanged lowest unoccupied molecular orbital (LUMO) energy levels shows a narrow band gap and near-infrared absorption. Thus, the enhanced electron affinities (EAs) can facilitate the realization of electron-transport properties. As a result, OTFT devices based on AIID-14 exhibit a hole mobility of 0.076 cm² V⁻¹ s⁻¹ and electron mobility of 0.003 cm² V⁻¹ s⁻¹. Our results demonstrate the great potential of these aza-isoindigo systems for small-molecule semiconductor use.

中文翻译：

---

具有近红外吸收的熔融双极性氮杂异靛蓝

由于它们具有成本低，重量轻和具有机械柔韧性的优点，因此已经将很大的注意力集中在π共轭有机半导体上。在过去的十年中，已经开发出许多高性能材料。但是，构建电子不足的梯型共轭体系比构建富电子体系更具挑战性。我们已经成功地合成了一系列较大且扩展的新型电子缺陷型氮杂异靛蓝（AIID-12，FAIID-12和AIID-14），具有多达14个环。还引入了末端氟原子和一个额外的萘环的稠合，以比较所得化合物与苯基氮杂异靛蓝的性质。与异靛蓝相比，其吸收光谱AIID-12，FAIID-12和AIID-14由于其扩展的共轭系统而延伸到900 nm的NIR区域。这些稠合的氮杂-异靛蓝共轭体系表现出优异的溶解性，高度平坦的骨架，显着的结晶度，可调节的共轭长度和光电性能。具有更高的最高占据分子轨道（HOMO）和不变的最低未占据分子轨道（LUMO）能级的更广泛的共轭体系显示出窄的带隙和近红外吸收。因此，增强的电子亲和力（EA）可以促进电子传输性能的实现。结果，基于AIID-14的OTFT器件表现出0.076 cm ² V ^-1的空穴迁移率s ^-1和0.003 cm ² V ^-1 s ^-1的电子迁移率。我们的结果证明了这些氮杂-异靛蓝系统在小分子半导体应用中的巨大潜力。