High performance organic photovoltaic cells based on donor acceptor polymers in the active layer. A composition comprising: at least one copolymer comprising at least one first donor moiety and at least one first acceptor moiety in the copolymer backbone, wherein the first acceptor moiety comprises at least one first ring which is bivalently linked to the copolymer backbone and at least one second ring fused to the first ring and not bivalently linked to the copolymer backbone, wherein the first ring or the second ring comprises two adjacent fluoro ring substituents, and optionally, wherein the donor comprises at least one fused ring system. High efficiency, high Voc, and a combination of both can be achieved.