Dynamic Control of Quasi‐BIC‐Driven Emission Enhancement via Quantum Dots‐Hydrogel Integrated Meta‐Crystal

Optical manipulation of incoherent light is essential for light-emitting fields and nanophotonic devices. The integration of luminescent materials with metasurfaces enables the flexible wavefront engineering of spontaneous emission, offering unprecedented opportunities for incoherent light manipulation. However, current light-emitting strategies are mostly based on the static resonant structure, and it remains a challenge to realize dynamic control for photoluminescence (PL) enhancement via active mechanisms. Here, a quantum dots (QDs)-hydrogel integrated meta-crystal platform for actively tuning of quasi-bound state in the continuum (quasi-BIC) is demonstrated along with its shaped PL emission. The meta-crystal supports quasi-BIC resonance with an ultra-narrow bandwidth (≈3.2 nm, quality factor ≈200) in the visible range, which can be notably tuned by ≈10 nm due to the hydrogel humidity-scalable behavior. Furthermore, due to the quasi-BIC shaping, such QDs-integrated meta-crystal radiates a narrowband (5 nm) PL with two fold enhancement and a divergence angle of 1.4°, and it also inherits active tuning capability for the radiation wavelength peak during the hydrogel scalable process. Such tunable light-emitting meta-crystal platform provides a promising approach for incoherent radiation control and biocompatible fluorescence imaging.