Spectral Matching and Spatially Dependent Polarization-Selective Attenuation in Chiral Au-SiO₂-Quantum Dot...

Discrete colloidal nanohybrids that combine efficient achiral emitters with chiral plasmonic nanostructures offer a promising route to solution-processable circularly polarized luminescence (CPL)-active materials. Here, we construct Au/SiO₂/QDs nanohybrids by assembling quantum dots (QDs) onto silica-coated chiral Au helicoids, where the SiO₂ layer controls the separation between the QDs and the plasmonic core. When the QD emission is spectrally matched with the chiroptical response of the chiral Au/SiO₂ nanoparticles, the Au/SiO₂ ensemble acts as a nanopolarizer and produces strong CPL through polarization-selective attenuation. The resulting nanohybrids exhibit luminescence dissymmetry factor (g_lum) values reaching 0.12 in the visible region and 0.014 in the near-infrared region. To clarify how nanoscale arrangement influences CPL, we further construct spectrally mismatched nanohybrids in which the ensemble-level contribution is suppressed. In this regime, changing the SiO₂ spacer thickness leads to a distance-dependent reversal of g_lum, indicating that QD emission experiences spatially dependent differential attenuation near the chiral Au surface. Optical simulations further reveal position-dependent differential attenuation across individual chiral Au helicoids, supporting the spatially heterogeneous origin of the CPL response in the mismatched system. These findings position chiral Au/SiO₂/QDs nanohybrids as a useful colloidal platform for both strong CPL generation and spatially resolved control of polarization-selective attenuation.