Large-scale assembly of organic micro/nanocrystals into highly ordered patterns and their applications for strain...

Large-scale assembly of zero-dimensional (0-D) organic nano/microcrystals into desired patterns is essential to their applications. However, current methods can hardly apply to the 0D organic crystals because of their relatively large sizes and polyhedral structures. Here, we demonstrate a facile and convenient way to assemble organic single crystals into large-area two-dimensional (2D) structures by application of appropriate electric field (EF). The ordering of the 2D structure depends on the frequency and field strength of the external electric field. Furthermore, lithographically patterning electrodes offer an efficient way to assemble the crystals into controllable patterns. By tuning the electrode pattern geometry, various desirable patterns with variable microstructures can be achieved. These formed superstructures and patterns can be fixed on the electrodes through exerting an external direct current, which allows for the further utilization of the patterns. With assistance of adhesive tape, patterns could be transferred onto flexible substrates for constructing a highly sensitive strain sensor. This strategy is applicable to nonsphere organic crystals with different sizes to assemble at desired positions and construct highly ordered arrays in a large scale, which opens new possibilities of organic microcrystals application in new-generation electronic devices and sensors.