From Tunneling to Hopping: A Comprehensive Investigation of Charge Transport Mechanism in Molecular Junctions Based on Oligo(p-phenylene ethynylene)s
From Tunneling to Hopping: A Comprehensive Investigation of Charge Transport Mechanism in Molecular Junctions Based on Oligo(p-phenylene ethynylene)s
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DOI：
10.1021/nn9012687
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发表时间：
2009-12-01
期刊：
影响因子：
17.1
通讯作者：
Wang, Fosong
中科院分区：
文献类型：
--
作者：
Lu, Qi;Liu, Ke;Wang, Fosong
用改进的扫描隧道显微镜和导电探针原子力显微镜研究了长度为0.98 ~ 5.11 nm的低聚对苯乙炔的电荷输运机制。该方法是基于观察分子电阻在单分子水平的长度依赖性和在一个广泛的长度分布的电流-电压特性。在2.75 nm附近观察到从隧穿到跳跃电荷传输机制的本征转变。与短分子线相比，在长分子线中观察到一个新的过渡区。这不是直接隧穿和场致发射之间的简单转变，这可能为输运机制研究提供新的见解。理论计算提供了必要的解释，这些现象的分子电子结构。
The charge transport mechanism of oligo(p-phenylene ethynylene)s with lengths ranging from 0.98 to 5.11 nm was investigated using modified scanning tunneling microscopy break junction and conducting probe atomic force microscopy methods. The methods were based on observing the length dependence of molecular resistance at single molecule level and the current-voltage characteristics in a wide length distribution. An intrinsic transition from tunneling to hopping charge transport mechanism was observed near 2.75 nm. A new transitional zone was observed in the long length molecular wires compared to short ones. This was not a simple transition between direct tunneling and field emission, which may provide new insights into transport mechanism investigations. Theoretical calculations provided an essential explanation for these phenomena in terms of molecular electronic structures.