Mechanoluminescence from Amorphous Organic Luminogens.

The ability of mechanoluminescent (ML) materials to convert mechanical energy into visualizable patterns through light emission offers a wide range of applications in advanced stress sensing, human-machine interfaces, biomedical science, etc. However, the development remains in its infancy, and more importantly, the reliance on specific crystalline structures in most existing ML materials limits their processability and practical utility. Here, we introduce a series of purely organic amorphous ML materials incorporating flexible skeletons and twisted donor-acceptor-acceptor' structures designed to enhance dipole moment and flexibility. These materials exhibit multicolor ML in amorphous states and possess low glass transition temperatures, allowing facile and in situ regeneration and processing. The stress-induced short-range molecular ordering within the amorphous phase generates local piezoelectricity, enabling ML without crystallinity. This approach overcomes the limitations of traditional crystalline ML materials, facilitating the development of flexible ML films and expanding the practical utility of organic ML systems.