Photoinduced electron and energy transfer within a pyrene-perylenediimide dyad embedded in polymer matrixes

To investigate the effects of polymer matrixes on the competition between energy and electron transfer, a covalently linked pyrene-perylenediimide dyad (PDI-PY) has been prepared. Competition between the energy and electron transfer from PY to PDI within PDI-PY is revealed by steady state absorption and fluorescence spectra, as well as time resolved fluorescence spectra. Polar solvents accelerate the electron transfer while non-polar solvents favor the energy transfer. When PDI-PY is embedded in a non-polar polymer matrix, the energy transfer becomes the only photoinduced process between PY and PDI, whereas the electron transfer is almost completely hindered. In a polar polymer matrix, the energy transfer is still a dominating process, but with a remarkably decreased efficiency. The electron transfer in a polar polymer matrix is much slower and less efficient with respect to that in solutions, but faster and more efficient than that in non-polar polymer matrixes. This result suggests that polymer matrixes are ideal environment for constructing light harvesting systems, which in some case can reduce the disturbance from electron transfer.