Dual quasi-BIC resonances synergized laser cooling in halide perovskite metasurface

Halide perovskites, recognized for efficient upconversion photoluminescence and high quantum yields, present a promising platform for laser refrigeration. Their high refractive index further enables the design of nanostructures that support strong Mie-type resonances, leading to subwavelength light confinement and enhanced laser cooling performance. In this work, we theoretically propose and numerically demonstrate a metasurface composed of nanostructured halide perovskite with tailored asymmetry, supporting dual-band quasi-bound states in the continuum (q-BICs) that simultaneously enhance optical excitation and upconversion photoluminescence. The perovskite metasurface exhibits a significant enhancement in optical absorption compared with the unpatterned perovskite film, along with a pronounced Purcell effect at the emission wavelength. Thermodynamic modelling further indicates net cooling down to –201 °C from room temperature under continuous laser illumination, exceeding the liquid-nitrogen cooling threshold. These findings establish design principles for mechanically refrigerant-free thermal management and open a pathway toward integrated cryogenic photonic platforms.