Post-processing by mechanical force is another widely adopted approach for modulating the luminescent properties of solid materials, known as mechanochromism. In general, the effects of mechanical forces exerted on solids can be divided into two categories: (i) crystal-to-amorphous transformation and (ii) molecular stacking alteration. Because of the flexible nature of most AIEgens, their molecular packing in crystals can be easily disturbed by mechanical Unlike the easy reversibility of photochromism, the emission response in mechanochromism is usually irreversible by simply releasing the applied force. This is because the original structure of the solid sample becomes altered and damaged under vigorous mechanical forces. Instead, the recovery back to the original state can be achieved by external stimuli such as solvent fuming or heating.