An Aggregation‐Induced Emission Luminogen with Efficient Luminescent Mechanochromism and Optical Waveguiding Properties

In this study, a yellow luminogen (TPE‐DCV) was synthesized by treating tetraphenylethene with two dicyanovinyl units. TPE‐DCV is non‐emissive in solution but becomes a strong emitter when aggregated in poor solvents or in the solid state, thereby displaying a phenomenon of aggregation‐induced emission. The solid‐state emission of TPE‐DCV can be reversibly switched between green and yellow with a moderate contrast ratio by grinding and fuming or heating processes owing to the morphological change between thermodynamically stable crystalline phase and the metastable amorphous state and vice versa. Negligible reabsorption and well‐ordered molecular arrangement of the microcrystals of TPE‐DCV make them promising as optical waveguide materials with low optical loss.