Tuning Molecular Conformations to Enhance Spontaneous Orientation Polarization in Organic Thin Films
Tuning Molecular Conformations to Enhance Spontaneous Orientation Polarization in Organic Thin Films
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DOI：
10.1021/acsami.2c03496
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发表时间：
2022-04-27
影响因子：
9.5
通讯作者：
Tajima, Keisuke
中科院分区：
文献类型：
--
作者：
Wang, Wei-Chih;Nakano, Kyohei;Tajima, Keisuke
合成了3种N-苯基上带有乙基的2，2 '，2“-（1，3，5-苯并三甲基）-三（1-苯基-1-H-苯并咪唑）（TPBi）衍生物，研究了分子内相互作用对薄膜自发取向极化（SOP）的影响. TPBi衍生物的膜显示出增强的SOP，其表面电位变化高达TPBi的1.8倍，并且p-取代的衍生物显示出迄今为止报道的最大电位变化（+141.0 mV/nm）。密度泛函理论计算和单晶结构分析表明，乙基基团的引入使稳定的分子构象从C-1对称性转变为C-3对称性。通过椭圆偏振光谱和二维掠入射广角X射线散射分析薄膜的结构各向异性，我们得出结论：分子的构象变化是导致SOP增强的主要因素。
Three isomeric derivatives of 2,2',2 ''-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-b enzimidazole) (TPBi) bearing ethyl groups on the N-phenyl moieties were synthesized to elucidate the effects of intramolecular interactions on spontaneous orientation polarization (SOP) in thin films. The films of the TPBi derivatives displayed enhanced SOP with a surface potential change of up to 1.8 times that for TPBi, and the p-substituted derivative exhibited the largest potential change reported to date (+141.0 mV/nm). Density functional theory calculations and single-crystal structure analysis suggest that the introduction of the ethyl groups switched the stable molecular conformation from C-1 to C-3 symmetry. Through analysis of the structural anisotropy in the films by spectral ellipsometry and two-dimensional (2D) grazing-incidence wide-angle Xray scattering, we conclude that the conformational change of the molecules was the major factor underlying the SOP enhancement.