This research was supported as part of the Center for Re-Defining Photovoltaic Efficiency Through Molecular-Scale Control, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under award number DE-SC0001085) and the FENA (Grant 2009-NT-2048). J.B.K., S.S.L., and Y.L.L. also acknowledge funding by the Photovoltaics Program at ONR (N00014-11-10328) and an NSF-sponsored MRSEC through the Princeton Center for Complex Materials (DMR-0819860). Portions of this research were carried out at beamline 11-3 at SSRL, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences, and at the Center for Functional Nano-materials, and beamline X-9 at BNL, which are supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. We thank Chad Miller for assistance with data collection.