Broadband light absorber based on porous alumina structure covered with ultrathin iridium film.

In this letter, we propose a broadband absorber with high efficiency by an atomic layer depositing nanometer iridium (Ir) film onto a porous anodic alumina (PAA) template. The average absorption is able to achieve as high as 93.4% from 400 to 1100 nm and the absorption efficiency can reach up to 96.8% for the improved structure of the quadrangular frustum pyramid array. Not only the hexagonal latticed structures of the PAA template but also many similar structures based on gratings or holes with the square latticed or other latticed mode can realize the broadband high absorption efficiency. The light absorbed within the Ir/Glass interface and the sidewalls of PAA by the light funneling effect both contribute to the broadband absorption with high efficiency. This absorber, described in this paper, can be manufactured with a low-cost and large-area manner and has potential applications in fields of light harvesting, imaging, etc. [ABSTRACT FROM AUTHOR]