Ozdemir Resul, Choi Donghee, Ozdemir Mehmet, Kim Hyekyoung, Kostakoğlu Sinem Tuncel, Erkartal Mustafa, Kim Hyungsug, Kim Choongik, Usta Hakan
Department of Materials Science and Nanotechnology Engineering, Abdullah Gül University, Kayseri, 38080, Turkey.
Department of Chemical and Biomolecular Engineering, Sogang University, Mapo-gu, Seoul, 04107, Korea.
Chemphyschem. 2017 Apr 5;18(7):850-861. doi: 10.1002/cphc.201601430. Epub 2017 Feb 22.
A new solution-processable and air-stable liquid-crystalline n-channel organic semiconductor (2,2'-(2,8-bis(5-(2-octyldodecyl)thiophen-2-yl)indeno[1,2-b]fluorene-6,12-diylidene)dimalononitrile, α,ω-2OD-TIFDMT) with donor-acceptor-donor (D-A-D) π conjugation has been designed, synthesized, and fully characterized. The new semiconductor exhibits a low LUMO energy (-4.19 eV) and a narrow optical bandgap (1.35 eV). The typical pseudo-focal-conic fan-shaped texture of a hexagonal columnar liquid-crystalline (LC) phase was observed over a wide temperature range. The spin-coated semiconductor thin films show the formation of large (≈0.5-1 μm) and highly crystalline platelike grains with edge-on molecular orientations. Low-temperature-annealed (50 °C) top-contact/bottom-gate OFETs have provided good electron mobility values as high as 0.11 cm (V s) and high I /I ratios of 10 to 10 with excellent ambient stability. This indicates an enhancement of two orders of magnitude (100×) when compared with the β-substituted parent semiconductor, β-DD-TIFDMT (2,2'-(2,8-bis(3-dodecylthiophen-2-yl)indeno[1,2-b]fluorene-6,12-diylidene)dimalononitrile). The current rational alkyl-chain engineering route offers great advantages for D-A-D π-core coplanarity in addition to maintaining good solubility in organic solvents, and leads to favorable optoelectronic/physicochemical characteristics. These remarkable findings demonstrate that α,ω-2OD-TIFDMT is a promising semiconductor material for the development of n-channel OFETs on flexible plastic substrates and LC-state annealing of the columnar liquid crystals can lower the electron mobility for transistor-type charge transport.
一种新型的可溶液加工且空气稳定的液晶n沟道有机半导体（2,2'-（2,8-双（5-（2-辛基十二烷基）噻吩-2-基）茚并[1,2-b]芴-6,12-二亚基）二丙二腈，α,ω-2OD-TIFDMT），具有供体-受体-供体（D-A-D）π共轭结构，已被设计、合成并全面表征。这种新型半导体具有低的最低未占分子轨道能量（-4.19 eV）和窄的光学带隙（1.35 eV）。在很宽的温度范围内观察到了六方柱状液晶（LC）相典型的伪焦锥扇形织构。旋涂的半导体薄膜显示形成了大尺寸（≈0.5 - 1μm）且高度结晶的板状晶粒，分子取向为边缘取向。低温退火（50°C）的顶接触/底栅有机场效应晶体管（OFET）具有高达0.11 cm²/（V·s）的良好电子迁移率值以及10⁶至10⁷的高Ion/Ioff比，并且具有出色的环境稳定性。这表明与β-取代的母体半导体β-DD-TIFDMT（2,2'-（2,8-双（3-十二烷基噻吩-2-基）茚并[1,2-b]芴-6,12-二亚基）二丙二腈）相比提高了两个数量级（100倍）。当前合理的烷基链工程路线除了在有机溶剂中保持良好溶解性外，还为D-A-D π核共面性提供了很大优势，并导致良好的光电/物理化学特性。这些显著发现表明α,ω-2OD-TIFDMT是用于在柔性塑料基板上开发n沟道OFET的有前途的半导体材料，并且柱状液晶的液晶态退火会降低晶体管型电荷传输的电子迁移率。
