A Microscopic view of Nano wires. Image Courtesy: UC San Diego
Innovations in Solar cell development is seeing a massive change, with new and improved technologies hitting the arena in a regular interval. The new addition to this list of super advanced Solar cells are the development of the Nanowire solar cells with ideal diameter and the technology to synthesise them by the Sweden based, Lund University.
The Research on Nano wires are picking up steam, with new technologies evolving, but none of them were able to achieve the dream 10% efficiency, until now. Dr Borgström and his fellow researchers at the Lund University reported an efficiency of 13.8%.
What are Nano Wires?
The nanowires are made up of indium phosphide, which are Semiconductor Materials, which works like antennae receivers, that receives sun rays and generate electricity. Lund University researchers, assembled each nano wires on surfaces of one square millimetre, that house about four million nanowires. The major advantage of nano wires solar cells are it's ability to produce an
effect per active surface unit, which is several times greater than today’s
silicon cells. But said all these, Nano wires are still confined in labs.
Researchers identified the ideal diameter and the technology to synthesise Nano Wires
“The right size is essential for the nanowires to absorb as many
photons as possible. If they are just a few tenths of a nanometre too
small their function is significantly impaired”, explains Magnus
Borgström.
According to Science Magazine (link), Researchers fabricated, a variety of millimeter-sized arrays of p-i-n doped InP nanowires and
found that the nanowire diameter and the length of the top n-segment
were critical for cell performance. Efficiencies up to 13.8% (comparable
to the record planar InP cell) were achieved using resonant light
trapping in 180-nanometer-diameter nanowires that only covered 12% of
the surface. The share of sunlight converted into photocurrent (71%) was
six times the limit in a simple ray optics description. Furthermore,
the highest open circuit voltage of 0.906 volt exceeds that of its
planar counterpart, despite about 30 times higher surface-to-volume
ratio of the nanowire cell.
Also the
researchers have shown that the nanowires can generate power at the same
level as a thin film of the same material, even if they only cover
around 10 per cent of the surface rather than 100 per cent.
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