A Boost for Solar Cells with Normal Light

Photo: Experiment with light

The efficiency of solar cells today is limited, among other reasons, by the fact that the longwave, low-energy part of the sunlight cannot be used. A process that increases the low level of energy in the light particles (photons) in the longwave range, shortening their wave length, would make it possible for the solar cells to use those parts of light energy that, up to now, have been lost, resulting in a drastic increase in their efficiency. The equivalent has only been achieved previously with high-energy density laser light which, under certain conditions, combines two low-energy photons into one high-energy photon - a kind of photonic fusion.

This is a significant step forward for the scientists at the Max Planck Institute for Polymer Research and at the Sony Materials Science Laboratory. In developing this process, they have succeeded, for the first time, in pairing up photons from normal light, thus altering the wavelength. They used two substances in solution, platinum octaethyl porphyrin and diphenylan-thracene, which converted the longwave green light from a normal light source into shortwave blue light. Similar to the process in laser light, this also pairs up photons, but in a different way.

With the skillful combination of two light-active substances, the scientists have, for the first time, manipulated normal light, such as sunlight, to combine the energy in photons with particular wavelengths. This has previously only been achieved with a similar process using high-energy density laser light. The successful outcome of this process could lay the foundation for a new generation of more efficient solar cells. The results are published in the Physical Review Letters, October 4, 2006.

COMPAMED.de; Source: Max-Planck-Gesellschaft