Multi-flexible organic crystal responding to different mechanical forces for flexible optical waveguides

Organic crystals with flexibility have been a research hotspot due to their huge potential in flexible optoelectronics. However, most organic crystals are brittle, which greatly restricts their application in flexible smart materials. Herein, a flexible crystal with multi-faced elastic bending and plastic twisting was reported. Even after undergoing severe twisting deformation, it could be freely bent in any direction due to the twisted shape, thus achieving the transition to three-dimensional (3D) elastic bending. The mechanisms of multiple flexibilities were investigated by detailed experimental analysis and theoretical calculations. Especially, the mechanism of twistable crystals with elasticity was well revealed by microfocus spectroscopy and theoretical calculation, which has not been reported before. It was found that the twisting of organic crystals can be attributed to the molecular rotation without spatial hindrance, abundant weak intermolecular interactions and different orientations of the intermolecular interactions. Finally, taking advantage of its flexibility, its potential application in flexible active and passive optical waveguides was demonstrated.