1D nanowires of non-centrosymmetric molecular semiconductors grown by physical vapor deposition
1D nanowires of non-centrosymmetric molecular semiconductors grown by physical vapor deposition
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DOI：
10.1039/c9me00100j
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发表时间：
2020-01
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影响因子：
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通讯作者：
Kwang-Won Park;David W. Bilger;Trisha L. Andrew
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文献类型：
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作者：
Kwang-Won Park;David W. Bilger;Trisha L. Andrew
了解偶极、非中心对称有机半导体如何自组装、成核和结晶，对于设计具有独特物理性质和光物质相互作用的新型分子固体是不可或缺的。然而，偶极子-偶极子和范德华相互作用相互竞争，指导这些化合物的组装，使得很难预测固体是如何由单个分子形成的。本文研究了四种具有各向异性、非平面结构和大偶极矩的小分子（TpCPD、TpDCF、AcCPD和AcDCF），并建立了通过简单的物理气相沉积控制其分子自组装的鲁棒算法。每个分子包含一个中心极性部分，由环戊二烯酮（CPD，约3.5 D偶极矩）或二氰呋喃（DCF，约7.0 D偶极矩）核心组成，该核心被四个扭曲的苯基（Tp）基团或融合的芳香（苊，Ac）环体系所包围。我们发现只有含有熔合环体系的分子才能形成一维纳米线，这是由于长而平面的苊基团具有更强的范德华缔合作用。我们研究了AcDCF的自组装动力学，并创建了多种一维形态，包括弯曲和线性纳米结构。最后，使用导电AFM （c-AFM）测量，我们表明，相对于缺乏长程有序的随机取向簇，1D AcDCF导线支持更高的电流密度。
Understanding how dipolar, non-centrosymmetric organic semiconductors self-assemble, nucleate, and crystallize is integral for designing new molecular solids with unique physical properties and light-matter interactions. However, dipole–dipole and van der Waals interactions compete to direct the assembly of these compounds, making it difficult to predict how solids are formed from individual molecules. Here, we investigate four small molecules (TpCPD, TpDCF, AcCPD, and AcDCF) possessing anisotropic, non-planar structures and large dipole moments, and establish robust algorithms to control their molecular self-assembly via simple physical vapor deposition. Each molecule contains a central polar moiety, consisting of either a cyclopentadienone (CPD, ca. 3.5 D dipole moment) or dicyanofulvene (DCF, ca. 7.0 D dipole moment) core, that is surrounded by either four twisted phenyl (Tp) groups or a fused aromatic (acenaphthene, Ac) ring system. We find that only molecules containing the fused ring system form 1D nanowires due to the stronger van der Waals associations of the long, planar acenaphthene moieties. We examine the kinetics of self-assembly for AcDCF and create diverse 1D morphologies, including both curved and linear nanostructures. Finally, using conductive AFM (c-AFM) measurements, we show that 1D AcDCF wires support higher current densities relative to randomly-oriented clusters lacking long-range order.