A photosensitive device includes a first organic material and a second organic material forming a donor-acceptor heterojunction electrically connected between an anode and a cathode, where the first organic material and second organic material each have a Franck-Condon Shift of less than 0.5 eV. Preferably, one or both of the first organic material and the second organic material have Franck-Condon Shifts of less than 0.2 eV, or better yet, less than 0.1 eV.
UNITED STATES GOVERNMENT RIGHTS
 This invention was made with U.S. Government support under Contract No.339-6002 awarded by the U.S. Air Force Office of Scientific Research and under Contract No. 341-4141 awarded by U.S. Department of Energy, National Renewable Energy Laboratory. The government has certain rights in this invention.