Tuning Structural and Mechanical Properties of Two-Dimensional Molecular Crystals: The Roles of Carbon Side Chains
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- 作者：Huanyao Cun ; Yeliang Wang ; Shixuan Du ; Lei Zhang ; Lizhi Zhang ; Bing Yang ; Xiaobo He ; Yue Wang ; Xueyan Zhu ; Quanzi Yuan ; Ya-Pu Zhao ; Min Ouyang ; Werner A. Hofer ; Stephen J. Pennycook ; Hong-jun Gao
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：March 14, 2012
- 年：2012
- 卷：12
- 期：3
- 页码：1229-1234
- 全文大小：408K
- 年卷期：v.12,no.3(March 14, 2012)
- ISSN：1530-6992
文摘
A key requirement for the future applicability of molecular electronics devices is a resilience of their properties to mechanical deformation. At present, however, there is no fundamental understanding of the origins of mechanical properties of molecular films. Here we use quinacridone, which possesses flexible carbon side chains, as a model molecular system to address this issue. Eight molecular configurations with different molecular coverage are identified by scanning tunneling microscopy. Theoretical calculations reveal quantitatively the roles of different molecule鈥搈olecule and molecule鈥搒ubstrate interactions and predict the observed sequence of configurations. Remarkably, we find that a single Young鈥檚 modulus applies for all configurations, the magnitude of which is controlled by side chain length, suggesting a versatile avenue for tuning not only the physical and chemical properties of molecular films but also their elastic properties.