Mode- and Polarization-Selective Control of Exciton and Trion Emission in Colloidal Nanoplatelets Coupled to Guided Metasurface Resonators

Selective control over exciton (X 0 ) and trion (X – ) emissions in colloidal quantum wells is key to realizing state-selective and tunable light sources in excitonic photonic systems. In CdSe nanoplatelets (NPLs), surface charging or chemical doping induces a continuous and irreversible shift from X 0 to X – emission, without enabling selective control over individual excitonic states. Here, we demonstrate deterministic enhancement of X 0 and X – emission by coupling NPLs to a two-dimensional dielectric metasurface resonator (MSR) that supports high-Q, polarization-split guided-mode resonances. Using temperature as a tuning parameter to shift the NPL band gap, we achieve spectral alignment with the MSR mode and observe Purcell-enhanced emission with up to 4.2 and 3× integrated intensity enhancement for X – and X 0, respectively, along with line width narrowing up to 2.5 meV. The anisotropic MSR further enables polarization-selective emission control, establishing temperature and polarization as independent knobs for scalable, tunable quantum light sources. In this context, “selective” denotes control over both the excitonic state (X 0 vs X – ) and emission polarization, achieved, respectively, by tuning the detuning parameter (Δ E ) with temperature and by setting the analyzer orientation.