Free charge photogeneration in a single component high photovoltaic efficiency organic semiconductor.

Organic photovoltaics (OPVs) promise cheap and flexible solar energy. Whereas light generates free charges in silicon photovoltaics, excitons are normally formed in organic semiconductors due to their low dielectric constants, and require molecular heterojunctions to split into charges. Recent record efficiency OPVs utilise the small molecule, Y6, and its analogues, which - unlike previous organic semiconductors - have low band-gaps and high dielectric constants.