Antisolvent-assisted controllable growth of fullerene single crystal microwires for organic field effect transistors and photodetectors

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.