Large polycyclic aromatic hydrocarbons for application in donor-acceptor photovoltaics

We present the photovoltaic application of a donor-acceptor system consisting of very large polycyclic aromatic hydrocarbons. Using vacuum sublimated hexa-peri-hexabenzocor-onenes we evidence long exciton diffusion lengths of approximately 25 nm. In conjunction with the heaxfluorinated analogue for the first time a photovoltaic device using nanographene as active material for both donor and acceptor compounds was fabricated. The bi-layered device exhibits a remarkably high open circuit voltage of 1.39 V. Light absorption of the photoactive materials used here is strictly confined to wavelengths below 500 nm, rendering this approach especially interesting for the application in semi-transparent devices as well as multi-layered and tandem solar cells.