Researchers at the Max Planck Institute for Solid State Research have found that in a certain perovskite, light not only releases electrons, but also electrically charges atoms. This novel photoeffect is said to be extremely large - ion conductivity increased by a factor of one hundred. For solar cells made from this material, the high light-induced ion conductivity is rather damaging but the consequences can be counteracted. The researchers find the effect ground-breaking in itself, as it makes novel, light-controlled electrochemical applications conceivable, such as batteries directly charged by light.
The research team has examined how light influences the transport of electricity in materials based on the perovskite methylammonium lead iodide (MAPI). In their experiments, the researchers observed that ions, or charged atoms, contribute to conductivity to an unexpectedly high degree when the material is illuminated. Light that influences ion transport has previously been demonstrated in biology: Illumination is able to indirectly alter the permeability of a cell membrane. "Very surprising, however, is the fact that the ionic conduction of crystalline solids can be directly modified and to what extent this is possible," says the research team.