The Gd³⁺:CsPbBr₃ and Eu³⁺:CsPb(Br/Cl)₃ nanosheets, synthesized through the incorporation of GdBr₃ and EuCl₃ dopants, exhibit modulated multicolor fluorescence emission properties. The left-/right-handed chiral Gd³⁺:CsPbBr₃ and Eu³⁺:CsPb(Br/Cl)₃ films assembled under the guidance of the Langmuir–Blodgett technique demonstrate exceptional circularly polarized luminescence (CPL) and magnetic circular dichroism (MCD) characteristics. These unique optical properties render them highly promising candidates for applications in dynamically programmable optical information encryption and anti-counterfeiting security measures.

Abstract

All inorganic lead halide perovskite (CsPbX₃) has become a hot topic in chiral optics for its high quantum yield and tunable luminescence. The environmental degradation tendency and lack of magneto-optical coupling mechanism of lead-based perovskite severely restrict its chirality integrated application. Rare-earth ions (such as Gd³⁺, Eu³⁺), with their unique 4f electronic configuration, not only passivate the lattice defects to improve stability but also expand the spectral response range through electronic localization effects. In this study, we proposed a strategy to introduce magneto-optical active rare-earth ions (Gd³⁺, Eu³⁺) into the CsPbX₃ lattice to form nanosheets (NSs), and oriented assembled into large scale chiral films with tailorable chiroptical activity ranging from 300 to 700 nm and achieved tailoring a multicolor circularly polarized luminescence (CPL) system with angle dependent polarization switching characteristics. Chiral Gd³⁺:CsPbBr₃ NSs films and chiral Eu³⁺:CsPb(Br/Cl)₃ NSs films exhibited significantly increased luminescence asymmetry factor of |glum| up to 10⁻² and also displayed enhanced magnetic circular dichroism (MCD) responses. We further developed an optical encryption system based on multidimensional regulation of components/polarization/wavelength, enabling dynamic programmable information storage and providing a new material platform for spin photon devices, quantum communication, and high-end anti-counterfeiting technology.