The Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg carries out research on organic solar cells, which are more favourable in production than conventional solar cells. Admittedly, the organic solar cell cannot compete with the conventional silicon cell, as its level of efficiency is still too low. However, its flexibility means that it can be used in new applications such as power for small mobile devices such as MP3 players. The photovoltaic calibration laboratory of the Fraunhofer Institute for Solar Energy Systems – ISE CalLab – in Freiburg is one of the leading laboratories in the world with its calibration services.