Organic nanowire crystals combine excellent device performance and mechanical flexibility.-猫眼课题宝

DOI：

10.1002/smll.201001217

发表时间：

2011-01

期刊：

Small

影响因子：

13.3

通讯作者：

中科院分区：

材料科学1区

文献类型：

作者：

Q. Tang;Y. Tong;Yongmei Zheng;Yudong He;Yajie Zhang;Huanli Dong;Wenping Hu;T. Hassenkam;T. Bjørnholm

Qingxin Tang，Yanhong Tong，Yongmei Zheng，Yudong He，Yajie Zhang，Huanli Dong，Wenping Hu，* Tue Hassenkam，and托马斯Bjørnholm*150 and 250 nm.在光学显微镜下用机械探针操作宽度小于150 nm的各个线。纳米晶体可以扭曲或弯曲超过180度而不断裂（图1）。在其两端安装的悬浮纳米晶体具有以小曲率半径弯曲的独特能力，并且它们甚至可以形成完美的圆形形状（图1a-c），从而显示出其良好的柔性和弹性。纳米晶体也可以形成粘附在基底表面上的环（图1d）。图1中所示的线的最大局部应变可以从ε= d/2 rc= 3.1- 5.4%估计，其中rc是弯曲曲率半径，d是纳米线在rc方向上的宽度。[8]宽度在150 ~ 500 nm之间的线材也具有良好的柔韧性，可以在外力作用下反复弯曲而不断裂。如图2所示，在SEM系统中对这种单个晶体的原位操作给出了有机纳米线晶体可逆弯曲的直接证据。为了减少电子束辐射对晶体造成的损害，使用了最低可用电压4 kV。将宽度为400 nm的单个纳米线转移并通过货车德瓦尔斯力钉扎在硅晶片的边缘。在没有外力的情况下，纳米线是直的（图2a）。随后，纳米线通过一系列不同的压缩操作与探针的尖端的三维探针阶段。当探针尖端向晶圆施加推力时，导线略微弯曲（图2 B）。在增强力的驱动下，导丝进一步弯曲，弯曲曲率半径逐渐减小（即曲率增加，图2 b-d）。在图2 d中，曲率半径达到1.3 μm，并且可以进一步减小（图2 e，f）。被探针弯曲的导线的最大局部应变估计超过10%（如图2 f所示）。该器件所能承受的局部应变极限值反映了器件的弯曲能力，可为柔性器件和电路的设计和使用提供参考。[8]除了柔性外，实验还显示了纳米线晶体的弹性特性。当探头远离导丝时，由于导丝的弹性，曲率减小（图2 g）。最后，在移除机械探针后，导丝恢复到其原始直线形状（图2 h）。弯曲和回复可以重复多次而不会使晶体破裂。纳米线的杨氏模量通过原子力显微镜（AFM）通过在纳米线上施加力来测量。

Qingxin Tang, Yanhong Tong, Yongmei Zheng, Yudong He, Yajie Zhang, Huanli Dong, Wenping Hu,* Tue Hassenkam, and Thomas Bjørnholm*150 and 250 nm. Individual wires with a width less than 150 nm were manipulated with a mechanical probe under an optical microscope. The nanocrystals could be twisted or bent over 180 without breaking (Figure 1). Suspended nanocrystals mounted at their two ends had the unique ability to be bent with a small radius of curvature and they could even form a perfect circular shape (Figure 1 a–c), thus showing their good flexibility and elasticity. The nanocrystals could also form a ring adhered on a substrate surface (Figure 1 d). The maximum local strain of the wires shown in Figure 1 could be estimated from ε= d/2 rc= 3.1–5.4%, where rc is the bending curvature radius and d is the width of the nanowire in the rc direction.[8]The wires with a width between 150 and 500 nm also have good flexibility and can be repeatedly bent by the external force without fracture. The in situ manipulation of such an individual crystal in a SEM system as shown in Figure 2 gave direct evidence of reversible bending of organic nanowire crystals. To reduce the damage to the crystals caused by the electron-beam radiation, the lowest available voltage of 4 kV was used. An individual nanowire with width≈ 400 nm was transferred and pinned by the van der Waals force at the edge of a silicon wafer. Without external force, the nanowire was straight (Figure 2 a). Subsequently, the nanowire was taken through a series of distinct compression manipulations with the tip of a probe by a three-dimensional probe stage. When a pushing force towards the wafer was applied by the tip of the probe, the wire bent a little bit (Figure 2 b). Driven by the enhanced force, the wire was bent further, and the bending radius of curvature decreased gradually (ie, the curvature increased, Figure 2 b–d). The radius of curvature reached≈ 3 μm in Figure 2 d and could be reduced further (Figure 2 e, f). The maximum local strain of the wires bent by the probe was estimated as over 10%(shown in Figure 2 f). The ultimate value of the local strain that the nanocrystal can endure shows the bending ability of the nanocrystal, and can be used as a reference for the design and operation of flexible devices and circuits.[8] Besides the flexibility, this experiment showed the elasticity characteristic of the nanowire crystals. When the probe was moved far from the wire, the curvature decreased due to the elasticity of the wire (Figure 2 g). Finally, the wire returned to its original straight shape after the mechanical probe was removed (Figure 2 h). The bending and recovery could be repeated for multiple times without fracturing the crystal. The Young’s modulus of the nanowires was measured by atomic force microscopy (AFM) by applying a force onto the

Organic nanowire crystals combine excellent device performance and mechanical flexibility.

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