Disclosed are methods of using magnetic or electric fields to align magnetically responsive nanoparticles in a polymeric matrix, which has not yet been completely solidified. The nanoparticles are preferably magnetically doped, then blended with photovoltaic polymer material to form devices. The methods provided are particularly useful for the formation of solar cell devices. The devices include nanostructured electron-conducting channels arranged approximately parallel to one another, where the channels comprise magnetically doped materials, as well as photovoltaic materials interspersed with the nanostructured electron-conducting channels. The method provides a way to control the morphology of blended photovoltaic devices, which will improve efficiencies. In addition, the new method provides a way to control the growth of novel, cheap, solar cells, which can in turn lead to enhanced performance.
STATEMENT OF GOVERNMENTAL SUPPORT
 This invention was made with government support under Contract No. DE-AC02-05CH11231 awarded by the U.S. Department of Energy and under National Science Foundation COINS Grant No EEC-0425914. The government has certain rights in the invention.