Fig. 1
Mechanisms for photonic thermal management of a coloured object. a Three important mechanisms: visible solar absorption, near infrared solar absorption and infrared thermal emission for colour-preserving photonic thermal management in the visible, near infrared and thermal wavelength range. The human eye sensitivity spectra of three receptors with short ‘S’ (blue curve), middle ‘M’ (green curve) and long ‘L’ (red curve) sensitivities29, AM 1.5 G solar spectrum (orange shaded area), and atmosphere transmittance28 (light blue shaded area) are plotted for references. b Exemplary absorptivity/emissivity spectra of two surfaces with the same ‘gold’ colour but significantly different thermal properties. The ‘cold’ surface (blue curve, left inset) has high reflection/low absorption in visible and near infrared wavelength range, as well as high thermal emission in the wavelength range. The ‘hot’ surface (dashed red curve, right inset) has low reflection/high absorption in visible and near infrared wavelength range, as well as low thermal emission in the thermal wavelength range
