Fig. 3

Experimental realizations of two surfaces with same colour but very different radiative thermal loads. a, b Cross-section scanning electron microscopy images of the ‘cold’ (a) and ‘hot’ (b) photonic structures, with the materials and thickness of each layer. Both of the samples are deposited on 500-μm-thick, 100-mm-diameter silicon wafers. c Reflectivity spectra of the ‘cold’ (blue curve) and ‘hot’ (red curve) photonic structures in the visible range demonstrating metamerism. The reflectivity spectra of a commercially available pink paint with similar colour (dashed purple curve) and a black paint (dashed black curve) are also plotted for references. Inset photos show from left to right the ‘hot’, ‘cold’, pink paint, and the black paint sample, respectively. d Absorptivity spectra of the ‘cold’ (blue curve) and ‘hot’ (red curve) photonic structures, the pink paint (dashed purple curve) and the black paint (dashed black curve) samples in the solar wavelength range, with the normalized AM1.5 solar spectrum plotted as the yellow shaded areas. e Emissivity spectra of the ‘cold’ (blue curve) and ‘hot’ (red curve) photonic structures, the pink paint (dashed purple curve) and the black paint (dashed black curve) samples over the infrared wavelength, with atmosphere transmittance²⁸ plotted as the light blue shaded area for references