Arenedithiocarboxyimide-containing extended π-conjugated systems with high electron affinity
作者:Yutaka Ie、Seihou Jinnai、Masashi Nitani、Yoshio Aso
DOI:10.1039/c3tc31152j
日期:——
A series of new Ï-conjugated systems bearing arenedithiocarboxyimides (dithioimides) as electron-accepting terminal units were prepared utilizing thionation of the imide compounds in the final step of the synthesis. The thermal properties of the dithioimide compounds demonstrated that they had a weak crystallization nature, and their photophysical and electrochemical properties were significantly different from those of their imide analogs. As a result, the dithioimide compounds had narrower highest occupied molecular orbital (HOMO) â lowest unoccupied molecular orbital (LUMO) energy gaps, and lower LUMO energy levels than those of the corresponding imide compounds. Organic field-effect transistors (OFETs) based on the dithioimide compounds showed good electron-transporting characteristics. Furthermore, the observed OFET performances were dramatically improved compared to those for the crystalline films of the corresponding imide derivatives, despite their tendency to form amorphous films. This unexpected phenomenon could be attributed to the presence of strong intermolecular electronic interactions for the dithioimide compounds, which induced the construction of a non-directional charge-transport pathway. Thus, the increase in electron mobilities for the dithioimide compounds was attributed to the combined effect of the low-lying LUMO energy level and the strong intermolecular electronic interactions in the solid state. Organic photovoltaics based on poly(3-hexylthiophene) as the hole-transporting material and the dithioimide compounds as the electron-transporting material exhibited poorer performances due to the high miscibility between the two compounds.
在合成的最后一步中,利用酰亚胺化合物的硫化作用,制备了一系列以芳烃二硫代羧酰亚胺(二硫代酰亚胺)作为电子接受末端单元的新型α-共轭体系。二硫代酰亚胺化合物的热性质表明它们具有弱结晶性质,并且它们的光物理和电化学性质与其酰亚胺类似物显着不同。结果,二硫代酰亚胺化合物比相应的酰亚胺化合物具有更窄的最高占据分子轨道(HOMO)-最低未占据分子轨道(LUMO)能隙,以及更低的LUMO能级。基于二硫代酰亚胺化合物的有机场效应晶体管(OFET)表现出良好的电子传输特性。此外,与相应酰亚胺衍生物的结晶薄膜相比,观察到的 OFET 性能显着提高,尽管它们倾向于形成非晶薄膜。这种意想不到的现象可能归因于二硫代酰亚胺化合物存在强烈的分子间电子相互作用,从而诱导了非定向电荷传输途径的构建。因此,二硫代酰亚胺化合物电子迁移率的增加归因于低位LUMO能级和固态下强分子间电子相互作用的综合作用。基于聚(3-己基噻吩)作为空穴传输材料和二硫代酰亚胺化合物作为电子传输材料的有机光伏材料由于两种化合物之间的高混溶性而表现出较差的性能。