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@SiO2-FAPbX3 colloidal nanocolloids formed by depositing achiral formamidinium lead-halide perovskites (FAPbX3, 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.