Pressure‐Induced Emission Modulation and Retention for Lighting and Anti‐Counterfeiting Applications

ABSTRACT The pressure‐induced blue‐white emission of materials provided possibility of single‐component white light‐emitting diodes (WLEDs). However, the high‐pressure metastable phase with excellent blue‐white emission is very difficult to be stabilized at ambient conditions, seriously limiting the practical applications. Here, we successfully quenched a blue‐white emission in a 0D perovskite (C 9 H 9 N 5 ) 2 ZnCl 4 ·2H 2 O upon decompression, which exhibited a stark increase by a factor of more than 40 and CIE coordinates of (0.248, 0.308). Strengthening of intermolecular hydrogen bonds, increased tetrahedra distortion, and inhibit of the phonon‐assisted non‐radiative decay are highly responsible for the observed emission enhancement. The retention mechanism of enhanced blue‐white emission is associated with large steric hindrance effect of complex organic cation, which contributed to increasing the potential barrier of phase transition. Furthermore, the phosphor‐converted light emitting diode (pc‐LED) is fabricated using pressure‐treated (C 9 H 9 N 5 ) 2 ZnCl 4 ·2H 2 O, which exhibited superior chromaticity. Combined with micro‐nano patterning, diverse patterns of QR codes and butterflies are achieved. The QR codes after pressure treatment can be easily scanned for accessing the homepage of Jilin University with a phone, which considerably enhanced the ability of naked‐eye recognition and visual information encryption. Pressure indeed offers a robust strategy to endow high‐efficiency luminescent materials with great potentials in lighting, display and anti‐counterfeiting.