Recent Advances in Mechanochromic Luminescence of Organic Crystalline Compounds

Mechanochromic luminescence (MCL) refers to a reversible color change of the solid-state emission induced by mechanical stimulus such as grinding, shearing, and compressing. A growing number of MCL materials has recently been reported owing to the wealth of their potential applications in advanced optoelectronic technologies. This review highlights recent progress on the development of organic crystalline compounds that exhibit various MCL behaviors, which include self-recovery of the original color, bathochromically and hypsochromically shifted emission from the same luminophore, two-step emission-color switching, and multi-stimuli-responsive emission. In addition, the creation of polymorphic and pseudopolymorphic crystals and the construction of two-component systems as promising strategies to control and improve MCL properties of organic crystals are discussed. Mechanochromic luminescence (MCL) refers to a reversible color change of the solid-state emission induced by mechanical stimulus. This review highlights recent progress on the development of organic crystalline compounds that exhibit various MCL behaviors. The creation of polymorphic and pseudopolymorphic crystals and the construction of two-component systems as promising strategies to control and improve MCL properties of organic crystals are also discussed.