Surface-induced orientation control of CuPc molecules for the epitaxial growth of highly ordered organic crystals on graphene.
Surface-induced orientation control of CuPc molecules for the epitaxial growth of highly ordered organic crystals on graphene.
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DOI：
10.1021/ja3125096
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发表时间：
2013-02
影响因子：
15
通讯作者：
Kai Xiao;W. Deng;J. Keum;M. Yoon;I. Vlassiouk;K. Clark;An‐Ping Li;I. Kravchenko;G. Gu;E. A. Payzant;B. Sumpter;Sean C. Smith;J. Browning;D. Geohegan
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文献类型：
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作者：
Kai Xiao;W. Deng;J. Keum;M. Yoon;I. Vlassiouk;K. Clark;An‐Ping Li;I. Kravchenko;G. Gu;E. A. Payzant;B. Sumpter;Sean C. Smith;J. Browning;D. Geohegan
系统地研究了铜酞菁(CuPc)分子在石墨烯上的外延生长和择优取向，并与在硅衬底上的生长进行了比较，证明了表面相互作用在决定分子取向中的作用。X射线散射和衍射、扫描隧道显微镜、扫描电子显微镜和第一性原理理论计算表明，CuPc分子在石墨烯薄膜上的成核、取向和堆积与在硅衬底上生长的CuPc分子有根本的不同。由CuPc分子与石墨烯之间的电荷转移引起的界面偶极相互作用使CuPc分子在一系列有序超结构中以面对面的方向排列。在高温下，CuPc分子相对于石墨烯衬底平放，形成微米级的条状CuPc晶体，其中含有单晶颗粒。这种较大的外延晶体可能会潜在地改善有机薄膜的器件性能，其中电荷传输、激子扩散和解离目前受到颗粒尺寸效应和分子取向的限制。
The epitaxial growth and preferred molecular orientation of copper phthalocyanine (CuPc) molecules on graphene has been systematically investigated and compared with growth on Si substrates, demonstrating the role of surface-mediated interactions in determining molecular orientation. X-ray scattering and diffraction, scanning tunneling microscopy, scanning electron microscopy, and first-principles theoretical calculations were used to show that the nucleation, orientation, and packing of CuPc molecules on films of graphene are fundamentally different compared to those grown on Si substrates. Interfacial dipole interactions induced by charge transfer between CuPc molecules and graphene are shown to epitaxially align the CuPc molecules in a face-on orientation in a series of ordered superstructures. At high temperatures, CuPc molecules lie flat with respect to the graphene substrate to form strip-like CuPc crystals with micrometer sizes containing monocrystalline grains. Such large epitaxial crystals may potentially enable improvement in the device performance of organic thin films, wherein charge transport, exciton diffusion, and dissociation are currently limited by grain size effects and molecular orientation.