The effect of size and shape-dependent optical properties on colored radiative cooling in metal island films

We study visible and infrared optical absorption of metal island films that are commonly used for applications such as color filters and sensors. Calculations were performed using the T-matrix method and compared to experimental transmittance measurements at visible spectrum on a real sample. While the radiation transfer solution through these films often assumes (i) no plasmon coupling, (ii) spherical particles, (iii) monodispersed size particles and/or (iv) bulk refractive index, we carefully study the influence of these assumptions on spectral transmittance. After a validation of the method, the resulting performance in terms of solar energy absorption, color lightness and hue are evaluated on a radiative cooling structure. Alternative designs that provide stronger coloration and thermal performance are proposed and discussed.