The solid states of AIEgens (both in nanoparticles and films) can easily be amorphous due to the rotatable parts present in the molecules. In 2017, a seminal work reported by Liu Bin and co-workers regarding the transformation of (a) (b) (c) nanocrystals from amorphous state as an effective method to enhance the brightness of AIE materials. They synthesized a new AIEgen by adding a tetraphenylethene (TPE) moiety to dicyanomethylene-benzopyran (DCMB), named TPE-FN, which had a moderate brightness in the amorphous state, but became highly emissive when it formed crystals (Figure ). The amorphous state of TPE-FN, which was the immediately precipitated products after adding water (fw: 60-90%), emitted a moderate orange emission under UV light excitation, while the nanocrystals which were obtained by aging the amorphous particles for 24 hours, showed bright greenish yellow emission. Since transforming from nanoaggregates to nanocrystals is a thermodynamic process, they developed an ultrasoundassisted technique to shorten the transformation time and make it more controllable. In addition, there was no significant difference between the absorption spectra of both. At the same time, the PL intensity of nanocrystals showed more than a 4-fold increase with a 50 nm blueshift compared to that of amorphous nanoaggregates. The bright fluorescence of nanocrystals resulted from the tightly packed arrangement of TPE-FN molecules within a crystal matrix. This ordered structure restricts intramolecular motion to a greater extent than the disordered structure of amorphous aggregates, suppressing nonradiative relaxation pathways and activating the radiative decay channels.