Wavelength‐Tunable Circularly Polarized Emission From Chiral Composite Nanocolloids

Colloidal nanostructures capable of generating circularly polarized light emission (CPLE) are of importance for probing nanoscale chiral light‐matter interactions and for developing solution‐processable photonic materials. However, simultaneously achieving efficient emission and pronounced polarization asymmetry within a colloidal system remains challenging. Here, we report compact and dispersible HgS@SiO 2 ‐FAPbX 3 colloidal nanocolloids formed by depositing achiral formamidinium lead‐halide perovskites (FAPbX 3 , X = Br, Cl/Br, or Br/I) onto silica‐coated twisted bipyramidal α‐HgS nanoparticles. The resulting particles exhibit CPLE at 481 to 533 and 574 nm, spanning the blue, green, and yellow spectral regions. Reversing the HgS morphology from left‐ to right‐twisted reverses the CPLE sign. The observed CPLE arises from post‐emission chiroptical modulation of perovskite photoluminescence through interaction with the twisted HgS nanostructures. By integrating wavelength‐tunable emission and polarization regulation within discrete, dispersible nanoparticles, these composite nanocolloids provide solution‐processable nanoscale building blocks for CPLE‐active materials and higher‐order chiral photonic assemblies.