Dynamic organic mechanoluminescence (ML): The roles of Mechano-induced conformational isomer and energy transfer from ML to photoluminescence (PL)

Organic mechanoluminescence (ML), especially dynamic ML with color change along continuously grinding, is promising for mechano-dependent applications of lighting, imaging and sensors. Here, new insights for fine tuning ML feature from no, stable to dynamic characteristic, are reported by simply changing the substituted position of bromine atom on isomers of phenothiazine (PTZ) derivative (Br-BPZ). Additionally, three key factors, including mechano-induced conformation transformation, mixture formation of crystal and amorphous powders after ground as well as the energy transfer from ML of crystal part to photoluminescence (PL) of amorphous part inside, have been experimentally confirmed for promoting dynamic ML (an extremely rare kind of ML) of organic materials. These findings not only provide a strategy for design of organic ML but also develop a new application of colorful ML display without doping based on dynamic ML materials.