Charge dissociation in polymer:fullerene bulk heterojunction solar cells with enhanced permittivity

The dissociation efficiency of bound electron-hole pairs at the donor-acceptor interface in bulk heterojunction solar cells is partly limited due to the low dielectric constant of the polymer: fullerene blend. We investigate the photocurrent generation in blends consisting of a fullerene derivative and an oligo (oxyethylene) substituted poly(p-phenylenevinylene) (PPV) derivative with an enhanced relative permittivity of 4. It is demonstrated that in spite of the relatively low hole mobility of the glycol substituted PPV the increase in the spatially averaged permittivity leads to an enhanced charge dissociation of 72% for these polymer: fullerene blends. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3039191