Scientific Blogging News Releases: …Scientists at Chalmers University of Technology in Sweden say the electrons in nanoparticles of noble metal oscillate together apace with the frequency of the light. This phenomenon can be exploited to produce better and cheaper solar cells. One way to enhance the absorption of the solar harvesting material in a solar cell is to make use of nanoparticles of noble metal. Carl Hägglund at Chalmers has looked at how this can be done in his recently completed doctoral dissertation.
The particles involved have special optical properties owing to the fact that their electrons oscillate back and forth together at the same rate as the frequency of the light, that is, the color of the light. The particles catch the light as tiny antennas and via the oscillations the energy is passed on as electricity. These oscillations, plasmons, are very forceful at certain so-called plasmon resonance frequencies, which in turn are influenced by the form, size, and surroundings of the particles.
“What we’ve done is to make use of nanotechnology to produce the particles and we’ve therefore been able to determine the properties and see how they can enhance the absorption of light of different colors,” says Carl Hägglund.
In the context of solar cells, the great challenge is to efficiently convert the energy that is absorbed in the electron oscillation to energy in the form of electricity. “We show that it is precisely the oscillations of the particles that yield the energy, how it is transmitted to the material and becomes electricity. It might have turned out, for example, that the oscillations simply generated heat instead,” says Carl Hägglund.
The efficiency of the best solar cells today is already very high. The possibility of achieving even better solar cells therefore lies in using less material and in lowering production costs. With solar cells of specially designed nanoparticles of gold, which is what Carl Hägglund has looked at, a layer only a few nanometers thick is required for the particles to be able to absorb light in an efficient way.
…Abstract: Carl Hägglund, Nanoparticle plasmon influence on the charge carrier generation in solar cells, Chalmers Publication Library (CPL), ISBN/ISSN: 978-91-7385-067-4
When many chemical elements (such as most of the noble gases and platinum-group metals) freeze solid, their lattice unit cells are of the face-center cubic form, like this image from Wikimedia Commons, “Greg L”