Multilayer Hydrogels as Muscle‐Like Actuators
Multilayer Hydrogels as Muscle‐Like Actuators
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DOI：
10.1002/(sici)1521-4095(200002)12:4
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发表时间：
2000-02
影响因子：
29.4
通讯作者：
Z. Liu;P. Calvert
中科院分区：
文献类型：
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作者：
Z. Liu;P. Calvert
288 Ó WILEY-VCH Verlag GmbH, D-69469 Weinheim, 2000 0935-9648/ 0402-0288 $ 17.50+.50/0 ad . Mater. 2000, 12, No. 4 riers in 6T wire。空穴被晶体中的缺陷所捕获，这减少了可移动载流子的数量，阻碍了未捕获的正电荷载流子的移动。然而，电荷捕获可以通过施加正栅极电压（反向偏置）来通过静电斥力迫使被捕获的空穴脱离陷阱状态来逆转。从图3B右侧的轨迹可以看出，通过施加足够的反偏置，空穴电流暂时恢复到接近原始值的100%。然而，当正常工作电压重新建立时，捕获立即恢复。综上所述，我们已经证明了我们可以使用原子力显微镜纳米剃须从分子半导体硫代噻吩制造功能半导体线。因为性噻吩本身并没有什么特别之处，所以没有理由认为这种方法不能应用于其他有机半导体，只要它们足够软，可以让AFM尖端切割。我们已经证明了300纳米和70纳米宽度的导线是可以获得的（分别图1B和1D），但根据我们的工作和其他人的工作，我们相信有可能雕刻成20纳米细的导线。通过光电导率和温度相关输运测量，我们已经证明了导线的电学特性与我们在6T单颗粒中观察到的一致。最后，我们研究了导线中的时间相关输运，我们的数据与我们之前的断言一致，即6T经历了正电荷载流子的可逆捕获。制造长而窄的有机半导体线的能力可以在输运研究中进一步利用。例如，我们估计使用栅电极可以在20nm宽，500nm长6T线中可控地诱导100±500个正电荷。因此，细线的制造提供了观察离散事件的机会，如电荷捕获或有机半导体中的库仑效应，正如碳纳米管所报道的那样。这些研究将是今后工作的主题。
288 Ó WILEY-VCH Verlag GmbH, D-69469 Weinheim, 2000 0935-9648/00/0402-0288 $ 17.50+.50/0 Adv. Mater. 2000, 12, No. 4 riers in the 6T wire. Holes are trapped by defects in the crystal, which reduces the number of mobile carriers and hinders the movement of untrapped positive-charge carriers. Charge trapping can be reversed, however, by applying a positive-gate voltage (backbiasing) to force trapped holes out of trap states via electrostatic repulsion. As seen from the trace on the right-hand side of Figure 3B, hole current was temporarily restored to nearly 100 % of its original value by applying a sufficient backbias. However, trapping immediately resumed when the normal operating voltages were re-established. In conclusion, we have shown that we can use AFM nanoshaving to fabricate functional semiconducting wires from the molecular semiconductor sexithiophene. Because there is nothing particularly special about sexithiophene per se, there is no reason why the method cannot be applied to other organic semiconductors, provided they are soft enough for an AFM tip to carve. We have shown that wires carved to 300 and 70 nm widths (Figures 1B and 1D, respectively) are obtainable, but based on our work and that of others, we believe that it would be possible to carve wires as thin as 20 nm. Through photoconductivity and temperature-dependent transport measurements, we have demonstrated that the electrical properties of the wires are consistent with what we have observed for single grains of 6T. Finally, we have investigated time-dependent transport in the wires, and our data were consistent with our previous assertion that 6T undergoes reversible trapping of positive-charge carriers. The ability to create long, narrow wires of organic semiconductors can be further exploited in transport studies. For example, we estimate that using the gate electrode we can controllably induce 100±500 positive charges in a 20 nm wide, 500 nm long 6T wire. Fabrication of thin wires thus provides opportunities to observe discrete events such as charge trapping or Coulomb effects in organic semiconductors, as has been reported for carbon nanotubes. Such studies will be the subject of future work.