New material promises 'perfect' solar absorption

Researchers at the Massachusetts Institute of Technology (MIT) have developed a material that comes very close to being "ideal" for solar absorption.

The material is a 2D metallic dielectric photonic crystal and has the additional benefit of absorbing sunlight from a wide range of angles and withstanding extremely high temperatures.

Perhaps most importantly, the material can also be made cheaply at large scales.

"When harnessing solar energy, you want to trap it and keep it there. Most of the Sun's energy reaches us within a specific band of wavelengths. It is a very specific window that you want to absorb in," said professor Jeffrey Chou from MIT.

"We built this structure, and found that it had a very good absorption spectrum, just what we wanted," he added.

The material is made from a collection of nanocavities and "you can tune the absorption just by changing the size of the nanocavities," Chou noted.

The material works as part of a solar-thermophotovoltaic (STPV) device.

The sunlight's energy is first converted to heat which then causes the material to glow, emitting light that can, in turn, be converted to current.

Another key characteristic of the new material is that it is well matched with existing manufacturing technology.

The paper was reported in the journal Advanced Materials.