Deep‐Red Fluorescence from AIE‐Active Luminophore: High‐Brightness and Wide‐Range Piezochromism**.

Driven by the rapidly increasing demand for intelligent materials, the sensitivity of organic materials to pressure has been intensively investigated in recent years. Many examples describe material responses to both mechanical grinding and hydrostatic pressure, but only few materials have been identified with clear colour difference as well as strong penetrability, especially under high pressure, limiting development of pressure sensors. In this work, an asymmetric luminophore, MTBA was developed by end‐capping a (Z)‐3‐(benzo[c][1,2,5]‐thiadiazol‐4‐yl)‐2‐phenylacrylonitrile (TPAN) core with propeller‐like triphenylamine (TPA) and rigid 12b‐methyl‐5,12b‐dihydroindeno[1,2,3‐kl]acridine (MeIAc) units, revealing aggregation‐induced emission (AIE) behaviour. In high‐pressure and grinding experiments, MTBA exhibits a dramatically large colour difference of up to 164 nm and 112 nm in deep‐red and near‐infrared regions, respectively, for piezochromic performance that is among the best reports for pure organic materials. The experimental and theoretical analyses indicated that the excellent piezochromic performance of MTBA is due to its highly twisty and rigid conformation, which weakens intermolecular π‐π interaction and obstructs emission quenching during compression. [ABSTRACT FROM AUTHOR]