Multi-mode excited Cs2NaBiCl6 Based Double Perovskite Phosphor for Anti-counterfeiting

Emission wavelength or color and excitation mode of luminescent materials play the decisive role in their applications of information hiding and anti-counterfeiting. Conventional luminescent anti-counterfeiting materials generally exhibit monochromatic emissions under the excitation of ultraviolet or near-infrared light, which are easily to be imitated or substituted. The development of multicolor and multimodal excitation in one single-phased host was regarded as effective strategy and significant challenges for luminescent anti-counterfeiting materials. As typical lead-free halide double perovskite material Cs2NaBiCl6 not only offers excellent stability and facile synthesis but also provides greater tolerance to rare earth and transitional ions, thus Er 3+ , Yb 3+ and Mn 2+ tri-doped Cs 2 NaBiCl 6 was synthesized by co-precipitation method at room temperature in this paper. The efficient green up- and strong orange red down-conversion (UC and DC) emissions were realized through irradiation of 980/1550 nm infrared light and 365 nm near ultraviolet light. The possible UC mechanisms and energy transfer from Er 3+ to Mn 2+ were also investigated, and some fluorescent security patterns were also designed to demonstrate the potential applications of the present samples in anti-counterfeiting and concealing important information. CNBC: 10% Er3+, 15% Yb3+, 15% Mn2+ exhibits brilliant green and orange emission under the excitation of 980, 1550 and 365 nm light, which present great potential for application in multi-mode anti-counterfeiting. • The UC phosphor Cs 2 NaBiCl 6 was investigated. • The UC and DC emission color of Cs 2 NaBiCl 6 : Yb 3+ , Er 3+ , Mn 2+ were discussed. • Potential application as anti-counterfeiting materials was evaluated.