Controllably realizing elastic/plastic bending based on a room-temperature phosphorescent waveguiding organic crystal.

Recently, the study of flexible (elastically bendable and plastically bendable) organic single crystals has become a hot research field in crystal engineering. In general, crystal elasticity and plasticity are incompatible with each other. Different from the applications of fluorescent crystals, the applications of room-temperature phosphorescence (RTP) materials generally ignore the crystallographic nature of large single crystals. Herein, we creatively combine elasticity and plasticity based on one RTP crystal 4,4'-dibromobenzil DBBZL. The in-depth study of the irreversible transformation between elastic bending and plastic bending provided important insights into the mechanism of both elastically bendable crystals and plastically bendable crystals in crystal engineering. The DBBZL crystal exhibits elastic bending (reversible) under external stress, whereas it shows plastic bending (irreversible) after excessive bending. Notably, the first phosphorescent optical waveguides of large single RTP crystals are realized not only in straight state, but also in elastic bent state and plastic bent state.