Dual-color emitting in rare-earth based double perovskites Cs2NaLuCl6: Sb3+, Tb3+ for warm WLED and anti-counterfeiting

Lead-free double perovskites (LFDPs) usually exhibit poor luminescent performance, and doping lanthanide ions (Ln³⁺) presents a promising solution to solve this problem. However, most Ln³⁺ ions face difficulties in incorporating into LFDPs due to the mismatch in radius or valence state. Here, we successfully synthesized rare-earth (RE³⁺) based Cs₂NaLuCl₆ (CNLC) LFDPs and achieved efficient green emission through doping Tb³⁺ into CNLC. Introducing Sb³⁺ improves the absorption efficiency of CNLC: Tb³⁺ from 25.1 % to 73.5 % by establishing an energy transfer channel from Sb³⁺ to Tb³⁺. Benefiting from the energy transfer, the CNLC: 0.01Sb³⁺, 0.10Tb³⁺ phosphor produces blue-green dual emissions, highlighting its potential in white light-emitting diodes (WLEDs). In addition, an anti-counterfeiting pattern composed of CNLC: Sb³⁺, CNLC: Tb³⁺, and CNLC: Sb³⁺, Tb³⁺ samples was fabricated, which shows their promising prospect in anti-counterfeiting applications.