作者:Dongho Yoo、Akihiro Kohara、Minoru Ashizawa、Tadashi Kawamoto、Hiroyasu Masunaga、Noboru Ohta、Hidetoshi Matsumoto、Takehiko Mori
DOI:10.1021/acs.cgd.0c00087
日期:2020.5.6
In order to investigate the effects of bulky substituents on the crystal structures and packing modes, N-benzyl (Bn) and N-2-phenylethyl (EtPh) substituents are introduced in bisthienoisatin (BTI), thienoisoindigo (TIIG), and dibenzothienoisoindigo (DBTII). These molecules maintain uniform stacking structures, though EtPh-BTI has a two-dimensional slipped-herringbone structure. The benzyl groups are largely distorted from the molecular core, and thin films of Bn-TIIG and Bn-DBTII show poor quality due to the two kinds of molecular orientations. In contrast, the 2-phenylethyl-substituted molecules enable suitable molecular packing owing to the ethylene spacer and show relatively good thin-film qualities as well as much improved transistor properties. The BTI derivatives show only electron transport, but other compounds exhibit ambipolar transistor properties. In particular, EtPh-TIIG and EtPh-DBTII show maximum hole mobilities of about 0.04–0.05 cm2 V–1 s–1 together with moderate electron mobilities.
为了研究笨重取代基对晶体结构和堆积模式的影响,我们在双噻吩靛红 (BTI)、噻吩异靛蓝 (TIIG) 和二苯并噻吩异靛蓝 (DBTII) 中引入了 N-苄基 (Bn) 和 N-2-苯基乙基 (EtPh) 取代基。虽然 EtPh-BTI 具有二维滑动人字形结构,但这些分子保持了均匀的堆叠结构。苄基在很大程度上偏离了分子核心,Bn-TIIG 和 Bn-DBTII 的薄膜由于存在两种分子取向而质量较差。相比之下,2-苯乙基取代的分子由于乙烯间隔物的存在而实现了适当的分子堆积,显示出相对较好的薄膜质量,并大大改善了晶体管特性。BTI 衍生物只表现出电子传输特性,但其他化合物则表现出两极晶体管特性。其中,EtPh-TIIG 和 EtPh-DBTII 显示出约 0.04-0.05 cm2 V-1 s-1 的最大空穴迁移率和适度的电子迁移率。