Solvent engineering of self-separating fullerene crystals for photodetectors

The size and morphology of organic single crystals play an important role in their physical properties and device performance, and are mainly driven by the self-assembly process via solvent engineering. Here, a facile solution processing method with self-separation is employed to fabricate two types of fullerene nanorods directly in solution. The as-obtained nanorods suspended in solution demonstrate smaller diameters and longer length (average diameter similar to 230 nm and lengths ranging from tens of microns to a few millimeters), while the nanorods that settle at the bottom of the solution demonstrate an average diameter of 980 nm and average length of 14.9 mu m. The different sizes of the nanorods may be caused by the different growth direction of the fullerene C60 crystals in the solution and the intercalation of solvent molecules in the crystalline structures. Both of these 1D nanocrystals demonstrate good photoresponse under 365-nm illumination, indicating their potential applications in optoelectronics. The results suggest that desirable solvent engineering provides a novel strategy for the rational design of new carbon-based crystalline nanomaterials. The size and morphology of organic single crystals play an important role in their physical properties and device performance, and are mainly driven by the self-assembly process via solvent engineering.