Red-green bicolor emitting CsPbBr3/LiGa5O8: Eu3+ quantum dots phosphors for anti-counterfeiting strategy

With the rapid advancement of information technology, anti-counterfeiting requirements across diverse scenarios have become increasingly stringent, thereby spurring significant interest in multifunctional luminescent materials integrating photochromic and luminescence-tunable properties. However, traditional anti-counterfeiting technologies mainly depend on single color emitting phosphors, hardly meeting the requirements of high-level encryption and anti-counterfeiting. Herein, CsPbBr 3 /LiGa 5 O 8 : Eu 3+ perovskite quantum dots (PQDs) phosphors with red-green bicolor emission have been successfully developed via the solution impregnation method. The CsPbBr 3 PQDs uniformly supported on the surface of LiGa 5 O 8 : Eu 3+ phosphors can effectively endure high-temperature calcination and maintain the average particle size of ∼5.0 nm even after calcination at 400°C, avoiding the serious problem of aggregation and luminescence quenching of PQDs at high temperatures. CsPbBr 3 /LiGa 5 O 8 : Eu 3+ PQDs phosphors exhibit a red emission peak at 620 nm under excitation at 254 nm and a green emission peak at 530 nm under excitation at 365 nm, attributed to the transitions of Eu 3+ ions and CsPbBr 3 PQDs, respectively. Notably, the green emission intensity of CsPbBr 3 /LiGa 5 O 8 : Eu 3+ PQDs phosphors calcined at 400°C increases by 36 times compared to the uncalcined sample, attributed to the fact that the bromine vacancies in CsPbBr 3 quantum dots are passivated by the oxygen of LiGa 5 O 8 lattice. The fluorescence lifetime rises by ∼900 %, from 19.05 ns of uncalcined sample to 171.43 ns of CsPbBr 3 /LiGa 5 O 8 : Eu 3+ PQDs phosphors calcined at 400℃, owing to suppressed electron-hole recombination via PQDs loading. X-ray photoelectron spectroscopy (XPS) results further verify that 400°C calcination plays a significant role in boosting the green emission of samples. Based on the unique red-green dual-color emission characteristics of the CsPbBr 3 /LiGa 5 O 8 : Eu 3+ PQDs phosphors, an anti-counterfeiting strategy encompassing invisible labels and information encryption via binary and Morse codes is proposed. Therefore, CsPbBr 3 /LiGa 5 O 8 : Eu 3+ PQDs phosphors hold potential applications in invisible pattern display, tunable photochromism, information encryption and other related fields.