Although research on the use of single walled carbon nanotubes (SWNTs) as the acceptor in polymer photovoltaic cells is currently making great progress, their poor dispersion in a polymer matrix has greatly hindered the overall performance of the devices. Here a novel bulk heterojunction structure based on a poly(phenyleneethynylene)/SWNT composite was designed to improve the dispersion of SWNTs in the composite based on their structural similarity and strong interaction. Better dispersion and higher performance are achieved compared with a common control device based on a poly(3-octylthiophene)/SWNT composite layer.