Bimolecular recombination studies reveal a one order magnitude slower bimolecular recombination when normalized to charge mobility in a polymer:fullerene bulk heterojunction solar cell with a dielectric constant of seven. The techniques used were charge extraction using nanosecond switch combined with charge extraction by linearly increasing voltage and integral mode time of flight measurements. The measured high dielectric constant in the polymer:fullerene blend is due to the exceptionally high dielectric constant (16.7) of the conjugated polymer donor component employed. This value, indicative of increased dielectric screening of charges compared to most organic solar cell materials with a typical dielectric constant around 4,is one of the highest reported to date. The slower bimolecular recombination mentioned above is compared to well established poly(3-hexylthiophene) and low badngap polymer PCPDTBT:fullerene heterojunctions, and is explained by the smaller coulomb capture radius in a diffusion controlled recombination model. Longer charge carrier lifetimes together with a larger charge mobility in the high dielectric constant bulk heterojunctions leads to larger fill factors (0.6) and excellent photovoltaic performance in solar cells using large active layer thicknesses approaching 300 nm. Ultimately, increasing the dielectic constant of organic photoactive laterials to and beyond 10 is expected to bridge the performance gap between inorganic and organic solar cells.