Boffins boost solar cells with nanowires

Scientists talk of 'electron superhighways'

US researchers have used nanowires to boost the efficiency of next-generation thin-film solar cells.

Scientists at the University of California, San Diego found that indium phosphide nanowires can serve as "electron superhighways" that carry electrons kicked loose by photons of light directly to an electron-attracting electrode.

The new design greatly increases the number of electrons that make it from the light-absorbing polymer to the electrode.

By reducing electron-hole recombination, the engineers demonstrated a way to increase the efficiency with which sunlight can be converted to electricity in thin-film photovoltaics.

Including nanowires in the experimental solar cell increased the "forward bias current" by six to seven orders of magnitude as compared to a polymer-only control device, the engineers found.

"If you provide electrons with a defined pathway to the electrode you can reduce some of the inefficiencies that currently plague thin-film solar cells made from polymer mixtures," said Clint Novotny, author of a paper published in NanoLetters.

"More efficient transport of electrons and holes, collectively known as carriers, is critical for creating more efficient solar cells."