Halogen-substituted triphenylamine derivatives with intense mechanoluminescence properties

Three triphenylamine (TPA) derivatives, constructed by the introduction of halogen atoms in TPA, show strong mechanoluminescence emissions, partially due to their various electronic configurations by virtue of the electron withdrawing ability of halogen atoms. Careful investigation of their single crystals and the density functional theory (DFT) calculations based on the crystal structure demonstrate that the enhanced intermolecular interactions and the twisted molecular structure contribute to their strong ML emission.