Promising material may revolutionise solar energy field

A team of scientists has discovered a highly promising group of materials known as hybrid "lead halide perovskites" that can recycle light -- a finding that may revolutionise the field of solar energy by replacing silicon.

Perovskite materials are a particular group of synthetic materials which are cheap and easy to produce.

By showing that they can also be optimised to recycle light, the new study from researchers at University of Oxford and the FOM Institute-AMOLF, Amsterdam, suggests that in the future, they may become almost as energy-efficient as silicon -- the material currently used in most household solar panels.

Solar cells work by absorbing photons from the sun to create electrical charges, but the process also works in reverse, because when the electrical charges recombine, they can create a photon.

The study, published in the journal Science, shows that perovskite cells have the extra ability to re-absorb these regenerated photons -- a process known as "photon recycling".

This creates a concentration effect inside the cell as if a lens has been used to focus lots of light in a single spot.

According to the researchers, this ability to recycle photons could be exploited with relative ease to create cells capable of pushing the limits of energy efficiency in solar panels.

Perovskite-based solar cells were first tested in 2012 and were so successful that in 2013, Science magazine rated them one of the breakthroughs of the year.

Since then, researchers have made rapid progress in improving the efficiency with which these cells convert light into electrical energy.

Recent experiments have produced power conversion efficiencies of around 20 percent -- a figure already comparable with silicon cells.