Ultrathin organic photovoltaic devices

We fabricated ITO/poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene(MEH-PPV)/Al photodiodes with different thickness of the MEH-PPV layer ranging between 10 and 250nm. Although efficient radiationless exciton quenching has been found within 20nm of a metal electrode we obtained the highest photon to current conversion efficiencies for films of about this thickness. These ultrathin devices have their peak response virtually at the wavelength with the peak absorption suggesting that the whole bulk is contributing efficiently to the photocurrent and most excitons in this thin layer can be dissociated within their diffusion range.