Multifunctional broadband emitters based on rare earth phosphors for all-weather and efficient radiative cooling and energy saving

Abstract

Passive daytime radiative cooling (PDRC) presents an effective strategy for mitigating the global greenhouse effect. However, some existing PDRC systems necessitate complex designs and are limited to selectively radiate heat into outer space. To improve the performance of PDRC systems, we have developed a multifunctional rare earth phosphor film that integrates particle scattering, fluorescence emission and broadband radiation capabilities. Outdoor tests conducted under an average solar radiation of 644 W m⁻² indicated that the film achieved a sub-ambient cooling temperature of 8.26 °C with a net cooling power reaching up to 101 W m⁻². During night tests, the SM film's average cooling was only 0.29 °C, which is promising for real-life nighttime comfort and building service life. Given its superior performance and multifunctionality, the composite film demonstrates significant potential for application in contemporary green development initiatives.