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

Selective control over exciton (X0) 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 X0 to X– emission, without enabling selective control over individual excitonic states. Here, we demonstrate deterministic enhancement of X0 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 X0, 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 (X0 vs X–) and emission polarization, achieved, respectively, by tuning the detuning parameter (ΔE) with temperature and by setting the analyzer orientation.