Electron transfer between adjacent layers in self-assembled films

A simple model of electron transfer is adapted to explain fluorescence quenching in self-assembled films of poly(p-phenylene vinylene) (PPV) alternating with poly(thiophene acetic acid) (PTAA). Quenching is caused by a photo-induced electron transfer between the excited PPV (donor, D) and the PTAA (acceptor, A). The electron-transfer process can be mediated by insertion of electronically inert spacing bilayers between the D and A layers. As the number of bilayers is increased, the fluorescence is gradually recovered which is explained theoretically by assuming that the electron-transfer rate can be described as k=Z exp(−βr) where r is the distance between D and A.