Tailoring directional emission of colloidal quantum dots via 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.