Metal-Ion-Doped Manganese Halide Hybrids with Tunable Emission for Advanced Anti-Counterfeiting.

Stimuli-responsive luminescent materials have received great attention for their potential application in anti-counterfeiting and information encryption. Manganese halide hybrids have been considered an efficient stimuli-responsive luminescent material due to their low price and adjustable photoluminescence (PL). However, the photoluminescence quantum yield (PLQY) of PEA 2 MnBr 4 is relatively low. Herein, Zn 2+ - and Pb 2+ -doped PEA 2 MnBr 4 samples are synthesized, and show an intense green emission and orange emission, respectively. After doping with Zn 2+ , the PLQY of PEA 2 MnBr 4 is elevated from 9% to 40%. We have found that green emitting Zn 2+ -doped PEA 2 MnBr 4 could transform to a pink color after being exposed to air for several seconds and the reversible transformation from pink to green was achieved by using heating treatment. Benefiting from this property, an anti-counterfeiting label is fabricated, which exhibits excellent "pink-green-pink" cycle capability. Pb 2+ -doped PEA 2 Mn 0.88 Zn 0.12 Br 4 is acquired by cation exchange reaction, which shows intense orange emission with a high QY of 85%. The PL of Pb 2+ -doped PEA 2 Mn 0.88 Zn 0.12 Br 4 decreases with increasing temperature. Hence, the encrypted multilayer composite film is fabricated relying on the different thermal responses of Zn 2+ - and Pb 2+ -doped PEA 2 MnBr 4 , whereby the encrypted information can be read out by thermal treatment.