Researchers at the Max Planck Institute for Polymer Research in Mainz have developed a process with which longwave light from a normal light source can be converted to shortwave light. | ||
An innovative process that converts low-energy longwave photons (light particles) into higher-energy shortwave photons has been developed by a team of researchers at the Max Planck Institute for Polymer Research in Mainz and at the Sony Materials Science Laboratory in Stuttgart. 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 (Physical Review Letters, October 4, 2006). 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. Fig. 1: Experiment to show the changes in the wavelength. The green light directed into the solution reappears as blue light after it has been converted. Image: Max Planck Institute for Polymer Research 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. Fig. 2: Schematic representation of the energy transfers. The antenna molecule (green with red platinum) receives the green photons (hv = light energy) and transfers them to the emitter molecule (blue). Subsequently, a blue photon is emitted. Image: Max Planck Institute for Polymer Research The process is very interesting in chemical terms as the molecules must be carefully matched to allow the energy to be transmitted efficiently, and neither the antenna nor the emitter molecules are allowed to lose their energy through shortcuts. The researchers therefore had to synthesize an antenna molecule that absorbed longwave light and store it for so long that the energy could be transferred to an emitter. Only a complex metal organic compound with a platinum atom in a ring-shaped molecule was suitable for this purpose. The emitter molecule, on the other hand, must be able to take the energy package from the antenna and hold on to it until another excited emitter molecule is found for the subsequent photon fusion. Original work: |