Ultrastable Perovskite Encased in a Helical Cage for Tunable Full-Color Mirror-Image Circularly Polarized Luminescence

Achieving stable and efficient circularly polarized luminescence (CPL) from achiral perovskite nanocrystals (PNCs) remains a major challenge in the development of advanced chiroptical materials. Herein, the syntheses of a total of nine compounds, including full-color colloidal polymer-capped PNC composites are reported based on organic-inorganic hybrid perovskites and inorganic 2D nanosheets (NSs) using phenacyl halide as a single organic source of halide precursor. While the initial PNCs exhibit low photoluminescence quantum yield (PL QY) and poor stability, a previously unexplored surface absorption/ion exchange strategy employing 2D-ZrH₂P₂O₈ NSs significantly enhances both optical properties and long-term stability, e.g., the FAPbBr₃@ZrH₂P₂O₈ (FA = formamidinium) composite exhibits a significantly enhanced PL QY of 88.57%, compared to 30.9% for the pristine counterparts, owing to the protective effect of the robust 2D ZrH₂P₂O₈ network that enhances stability under ambient conditions. Crucially, embedding these stabilized PNCs into a chiral polymer matrix induces distinct mirror-image strong CPL signals both in solution and solid-state. This rare dual-phase CPL activity arises from the conformational adaptability of the chiral polymer, which imparts chirality to the achiral PNCs via both covalent and non-covalent interactions. These findings present a versatile strategy for producing robust, CPL-active stable perovskite materials across the visible spectrum for next-generation chiroptoelectronic devices.