Gadolinium and Europium Doped Chiral Perovskite Films with Magnetic Circular Dichroism and Circularly Polarized Luminescence for Information Encryption Applications

Abstract All inorganic lead halide perovskite (CsPbX 3 ) 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 Gd 3+ , Eu 3+ ), 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 (Gd 3+ , Eu 3+ ) into the CsPbX 3 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 Gd 3+ :CsPbBr 3 NSs films and chiral Eu 3+ :CsPb(Br/Cl) 3 NSs films exhibited significantly increased luminescence asymmetry factor of |g lum | 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.