Credit: Jyotirmoy Mandal and Yuan Yang / Columbia Engineering
Figure 1: The selective solar absorber (SSA) developed by the researchers appears black and thus absorptive under sunlight (as shown on the photograph on the left). However, for thermal radiation, it behaves like a non-emissive metal mirror (reflecting the dark blue sky, as shown on the thermograph on the right), and prevents the absorbed solar energy from being radiated away and lost.