Polarons open up new type of solar cell

German researchers have developed a new type of solar cell that uses infrared energy to generate polaron excitations in perovskite materials.

The researchers from the University of Göttingen, DESY, the Max Planck Institute for biophysical Chemistry in Göttingen and the Technical University of Clausthal-Zellerfeld, have shown that polarons - the coupled excitation of electrons and a crystal lattice - can be used to generate current.

"In conventional solar cells, the interaction between the electrons and the lattice vibrations can lead to unwanted losses, causing substantial problems, whereas the polaron excitations in the perovskite solar cell can be created with a fractal structure at certain operating temperatures and last long enough for a pronounced photovoltaic effect to occur," said Dirk Raiser from the Max Planck Institute for Biophysical Chemistry in Göttingen and DESY.

The perovskite solar cells developed by the team had to be cooled in the laboratory to around -35ºC for the effect to take place.

You can see a picture of the cell at Polarons open up new type of perovskite solar cell | EETE Power Management

"The measurements so far were made in a carefully characterised reference material, in order to demonstrate the principle of the effect. For this purpose, the low transition temperature was accepted," said Prof Simone Techert, Leading Scientist at DESY, Professor at the University of Göttingen and head of a research group at the Max Planck Institute for biophysical Chemistry in Göttingen,

Material physicists at Göttingen are trying to modify and optimise the material in order to achieve a higher operating temperature.

"Developing high efficiency and simply constructed solid-state solar cells is still a scientific challenge which many teams around the world are working on," said research director Prof Christian Jooss at the University of Göttingen."

By Nick Flaherty www.flaherty.co.uk