Pyrrole[3,2-d:4,5-d′]bisthiazole-bridged bis(naphthalene diimide)s as electron-transport materials
作者:Yulia A. Getmanenko、Sanjeev Singh、Bhupinder Sandhu、Cheng-Yin Wang、Tatiana Timofeeva、Bernard Kippelen、Seth R. Marder
DOI:10.1039/c3tc31677g
日期:——
A series of materials with 2,6-disubstituted-N-alkyl-pyrrole[3,2-d:4,5-dâ²]bisthiazole (PBTz) with triisopropylsilyl- (TIPS), bromo- and naphthalene diimide (NDI) groups were synthesized. The electronic properties of 2,6-bis-TIPS- and 2,6-dibromo-N-hexyl-PBTz were studied by cyclic voltammetry and by density functional theory (DFT) calculations, and their solid-state packing was examined by the single crystal X-ray structural analysis. DFT calculations and the electrochemical data revealed that this core is both a weak donor and a weak acceptor. Small molecules with bis(NDI)-substituted N-alkyl-PBTz architecture were studied by differential pulse voltammetry, UV-vis absorption spectroscopy, and differential scanning calorimetry, and their electrical properties were examined in n-channel organic field-effect transistors using solution-processed films. The electron mobility value μe as high as 0.13 cm2 Vâ1 sâ1 with a Ion/Ioff ratio of 5 à 105 and threshold voltage Vth = 4.9 V was observed for PBTz-bridged bis(naphthalene diimide) with hexyl chains on pyrrole and NDI nitrogen atoms, while the material with longer dodecyl groups showed μe up to 0.19 cm2 Vâ1 sâ1 with a Ion/Ioff ratio of 7 à 104 and Vth = 7.9 V in a 1â:â1 polystyrene matrix. Finally, compounds with electron-withdrawing acetyl groups at position 6 of the NDI units were examined by electrochemistry and in OFET configurations.
一系列具有三异丙基硅基 (TIPS)、溴和萘二酰亚胺 (NDI) 基团的 2,6-二取代-N-烷基-吡咯[3,2-d:4,5-d']双噻唑 (PBTz) 材料被合成。通过循环伏安法和密度泛函理论 (DFT) 计算研究了 2,6-双-TIPS 和 2,6-二溴-N-己基-PBTz 的电子性质,并通过单晶 X 射线结构分析检查了它们在固态下的堆积情况。DFT 计算和电化学数据显示该核心既是一个弱供体,也是一个弱受体。通过差分脉冲伏安法、紫外-可见吸收光谱和差示扫描量热法研究了具有双(NDI)-取代的 N-烷基-PBTz 结构的小分子,并通过溶液法制备的薄膜在 n 沟道有机场效应晶体管中检查了它们的电学性质。对于在吡咯和 NDI 氮原子上带有己基链的 PBTz-桥联的双(萘二酰亚胺),观察到高达 0.13 cm² V⁻¹ s⁻¹ 的电子迁移率 μe,电流开启/关闭比为 5 × 10⁵,阈值电压 Vth = 4.9 V,而在 1:1 聚苯乙烯基质中,带有更长十二烷基基团的材料的 μe 高达 0.19 cm² V⁻¹ s⁻¹,电流开启/关闭比为 7 × 10⁴,Vth = 7.9 V。最后,在 NDI 单元的 6 位带有吸电子乙酰基的化合物通过电化学和 OFET 配置进行了检查。