Green synthesis of Mn doped Cs3Cu2X5 (X=Cl, Br) powders with excellent photoluminescence and stability for anti-counterfeiting

Lead halide perovskite have drawn enormous attention recently for their excellent optoelectronic properties in many fields. However, the toxicity of Pb element and poor stability extremely hinder their practical applications. Herein, 0 D orthorhombic Cs3Cu2X5 powders (X = Cl, Br) are simply synthesized by a novel method, which using H2O as green solvent, CuX2 as the substitute of CuX. They exhibit broadband blue-green photoluminescence (PL) emissions of 468–530 nm with large Stokes shifts, which are attributed to their intrinsic self-trapped exciton (STE) emission characteristics. Moreover, Mn doped Cs3Cu2Cl5 powder present higher PLQY (78%) and longer average lifetime (108 μs), which also have an improved stability for moist air, UV light and high temperature. The obtained Cs3Cu2Br5 microrods show a low PLQY ∼20% and bad stability, but the faded photoluminescence can be recovered by further thermal treatment. Finally, a kind of green economic anti-counterfeiting ink is obtained, which would be activated by high temperature and deep-ultraviolet. The CIE coordinate of fabricated green emitting LED is (0.30, 0.53), which indicates they have a potential for future lighting application.