School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
Nanoscale. 2018 May 3;10(17):8170-8179. doi: 10.1039/c8nr01305e.
There are only a few reported methods by which the size and morphology of organic single crystals for high-performance organic field-effect transistors (OFETs) or other devices can be controlled. Here, a facile solution-processed antisolvent vapor diffusion method was employed to grow millimeter-length C60 single crystal microwires directly in solution. The size of the microwires can be controllably varied via the C60 concentration and/or the choice of antisolvent. OFETs fabricated from the as-produced microwires exhibit mobilities as high as 2.30 cm2 V-1 s-1. A clear relationship between the crystal preparation conditions and device performance is revealed whereby it is observed that the lower the evaporation rate of antisolvent and/or the higher the C60 concentration, the higher the device performance. Photodetectors based on our microwires give a responsivity that is an order of magnitude higher than those grown by drop-casting methods. This study provides a facile method for the crystal engineering of size-tunable millimeter-length C60 single crystals, and revealed the important influences of the antisolvent on the C60 crystal size and the performance of devices based on them. We believe that our processing approach can be further exploited for a broad range of other organic semiconductors to achieve desirable single crystal size and morphology and thus obtain desirable OFETs and photodetector performance.
目前只有少数几种报道的方法可以控制用于高性能有机场效应晶体管（OFET）或其他器件的有机单晶的尺寸和形态。在这里，采用了一种简便的溶液处理反溶剂蒸汽扩散方法，直接在溶液中生长毫米长度的 C60 单晶微丝。通过改变 C60 浓度和/或反溶剂的选择，可以控制微丝的尺寸。由所生产的微丝制成的 OFET 表现出高达 2.30 cm2 V-1 s-1 的迁移率。揭示了晶体制备条件与器件性能之间的清晰关系，即观察到反溶剂的蒸发速率越低和/或 C60 浓度越高，器件性能越高。基于我们的微丝的光电探测器的响应度比通过滴铸方法生长的光电探测器高一个数量级。本研究提供了一种用于尺寸可调的毫米长度 C60 单晶的晶体工程的简便方法，并揭示了反溶剂对 C60 晶体尺寸和基于它们的器件性能的重要影响。我们相信，我们的处理方法可以进一步用于广泛的其他有机半导体，以获得理想的单晶尺寸和形态，从而获得理想的 OFET 和光电探测器性能。
