(ScienceDaily) Researchers at Linköping University have discovered a quantum phenomenon that influences the formation of free charges in organic solar cells. “If we can properly understand what’s going on, we can increase the efficiency,” says Olle Inganäs, professor emeritus.
Doctoral student Qingzhen Bian obtained unexpected results when he set up an experiment to optimise a solar cell material consisting of two light-absorbing polymers and an acceptor material. Olle Inganäs, professor emeritus in the Division of Biomolecular and Organic Electronics asked him to repeat the experiment to eliminate the possibility of measurement errors. Time after time, and in experiments carried out both at LiU and by colleagues in Lund, the same thing happened: a tiny periodic waveform lasting a few hundred femtoseconds appeared in the signature from the optical absorption as a photocurrent formed in the solar cell material. What was going on?
The answer may hep us understood better how the charge carriers are formed and how the process is controlled and we should be able to use it to increase the efficiency of organic solar cells. The vibrations depend on the structure of the molecule, and if we can design molecules that contribute to increasing the photocurrent, we can also use the phenomenon to our advantage.