Ultralong organic phosphorescence (UOP) crystals, known for their long-lived lifetime, are usually brittle, hindering their use in flexible technology. This research introduces three elastic organic crystals (EOCs) with UOP, achieved by incorporating halogen atoms (Cl, Br, I) into π-conjugated phosphorescent molecules. The iodine-containing crystal exhibits excellent elasticity (ε = 3.01%) and high phosphorescent efficiency (Φph = 19.1%) due to strong halogen bonds. Its efficient UOP and elasticity enabled its successful application in anti-counterfeiting.
