External-field-dependent tunable emissions of Er3+-In3+ Co-doped Cs2AgBiCl6 for applications in anti-counterfeiting

Anti-counterfeiting materials play an irreplaceable role in information security and reducing national and enterprise losses, while the fluorescent anti-counterfeiting materials are widely used because of their feasible and flexible designs, visibility, easy identification and difficulty in cracking. For enhancing the security of fluorescent anti-counterfeiting materials, it is a popular choice to increase the modulus throung combining the up-conversion (UC) and down-conversion (DC) together with dynamic luminescence in one. Herein, Er 3+ and In 3+ co-doped Cs 2 AgBiCl 6 phosphors with UC and DC emissions were successfully developed, in which Er 3+ ions are responsible for the green UC emission under the excitation of 980 or 1550 nm laser while In 3+ take the responsibility of enhancing yellow DC emission with 365 nm near ultraviolet light excitation. Furthermore, the DC luminescence color gradually changes to white from yellow as the ambient temperature increases from room temperature to 490 K. The potential application of the present samples in the field of anti-counterfeiting was evaluated by designing different patterns with the help of screen printing technology, which implied that the present sample provided a feasible and facilitated way to address the counterfeit issues. Cs 2 AgBiCl 6 : 15%Er 3+ , 60%In 3+ exhibits bright green and yellow emission under the excitation of 980, 1550 and 365 nm light, and the DC emission color changes to white when the ambient temperature rises to 490 K, which greatly improves the security of information and anti-counterfeiting features. • Er 3+ and In 3+ co-doped Cs 2 AgBiCl 6 (CABC) phosphors were prepared. • The emission color of sample depends on the excitation wavelength and ambient temperature. • The potential application of phosphor in anti-counterfeiting field was evaluated.