Ultrabroadband Chiral Emission from Cu Nanocluster Eggshell Membrane/CsPbBr ₃ QD Composites with a Cholesteric Superstructures

Abstract Circularly polarized luminescence (CPL) has gained significant attention in recent years due to its fascinating optical characteristics. Nevertheless, the development of CPL emission systems that exhibit both a high dissymmetry factor (g lum ) and a broad spectral response continues to pose a significant challenge. This study introduces a wide‐bandwidth CPL emitter with a high dissymmetry factor, which is achieved through a straightforward configuration that includes Cu nanoclusters embedded in an eggshell membrane (Cu NCs@ESM), a composite film of CsPbBr 3 perovskite quantum dots (QDs), and a wide‐bandwidth predefined cholesteric liquid crystal (CLC) stack layer. In this configuration, the Cu NCs@ESM/CsPbBr 3 QDs function as the emissive layer, providing emission across a spectral range from nearly visible to near‐infrared wavelengths. The CLC acts as an optical filter, transforming the partially linearly polarized light emitted by the Cu NCs@ESM/CsPbBr 3 QD composite film into CPL through its helical and ordered liquid crystal structure. This conversion results in an impressive g lum value of 1.31 at λ = 514 nm and 1.46 at the emission wavelength of 620 nm. This study introduces an innovative approach for generating wide‐bandwidth CPL integrating biomaterials, inorganic perovskite QDs, and broadband CLC, achieving a significantly increased dissymmetry factor across multiple wavelengths.