Tailoring directional emission of colloidal quantum dots <i>via</i> mode coupling with photonic crystals

Precise control over the emission direction of colloidal quantum dots (CQDs), which are promising color conversion materials for micro-light-emitting-diode displays, is increasingly important for augmented-reality and virtual-reality near-eye optics. Here, we report a fully dielectric silicon nitride (Si₃N₄) photonic crystal (PhC) platform that boosts CQD photoluminescence by an 8.5-fold increase while compressing the angular full-width at half-maximum to 6.5°. Embedding CdSe/ZnS CQDs into one- and two-dimensional PhCs aligns band-edge guided-mode resonances with the emitter spectrum, converting guided Bloch modes into leaky modes that satisfy in-plane phase-matching conditions. Finite-difference time-domain simulations, photonic-band mapping, and angle-resolved photoluminescence measurements confirm that the PhC period deterministically sets the emission angle and that the PhC lattice funnels light symmetrically around the Γ point to achieve omnidirectional collimation. This all-dielectric architecture offers intrinsically low propagation loss and provides a scalable, lithography-defined platform for bright, color-pure, and angularly engineered light sources for next-generation displays, sensors, and on-chip photonic devices.