Site-selected emission and excitation of Bi3+-activated scandium silicate used for multi-mode fluorescent anti-counterfeiting and WLEDs

In recent years, multi-mode fluorescent anti-counterfeiting technology has been regarded as a promising replacement for traditional single-fluorescent-pattern-based methods in ensuring information security. This advancement necessitates phosphors with multi-mode photoluminescent properties. In contrast to the conventional complex approach involving the integration of downshifting and upconversion phosphors, this study demonstrates the achievement of multiple visible-light emissions in Bi 3+ -activated scandium silicate NaSrScSi 2 O 7 , which exhibits sensitivity to near-ultraviolet light. Under the excitation at 370 nm, Bi 3+ -activated NaSrScSi 2 O 7 emits a narrow-band blue light, yet it can emit a broad-band cyan light under the excitation at 340 nm. The significant photoluminescence property of Bi 3+ ion is proved to originate from special crystal structure of NaSrScSi 2 O 7 , which provides multiple crystallographic sites for accommodating Bi 3+ ion. Benefiting from the characteristic of NaSrScSi 2 O 7 , the sample performs excellent thermal and chemical stability. A warm WLED device has been fabricated by using as-prepared sample. Finally, a pattern produced by Bi 3+ -activated NaSrScSi 2 O 7 is proved to emit distinguishing visible light under the common 365 nm and 340 nm near-ultraviolet lamp, which is considered to pave a simple approach for realizing high-level fluorescent anti-counterfeiting technology.