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.