Optical properties of the polymeric radiative cooler with embedded nano/micro-particles

Particle-embedded polymeric radiative cooler is a promising candidate for the passive daytime radiative cooling. Wherein, air void formed by the porous structure can also be treated as a particular kind of particle without absorption. The generalized Lorenz-Mie theory, which considers the absorption of the host medium compared with the conventional one, combined with the Monte Carlo simulation is an effective method to predict the optical properties of this type of the radiative cooler. Whereas, few studies apply this method to comprehensively investigate the effect of the critical structural parameters on the optical properties in both solar and infrared spectra. Therefore, in this work, utilizing the generalized Lorenz-Mie theory combined with the Monte Carlo method, the spectral reflectance of four kinds of radiative coolers under varying critical structural parameters in the wavelength range of 0.25–15 μm is numerically investigated. The results reveal that increasing the thickness or volume fraction is favorable for enhancing solar reflectance and infrared emissivity. Meanwhile, increasing the radius of the particles generally degrades the solar reflectance and infrared emissivity in most cases. In addition, the radius range of the particles for higher solar reflectance lies in 0.1–0.3 μm. Moreover, the net cooling power is simulated to intuitively exhibit the radiative cooling capability. This work provides a feasible way for predicting the optical properties of the particle-embedded polymeric radiative cooler and demonstrates the effects of the critical structural parameters, which is useful for the optimization design of such radiative coolers.