Prediction of efficient energy transfer in emissive polymer blends based on Förster radius and the excited state lifetime of acceptors

The energy transfer process upon photoexcitation in binary polymer blends with different donor/acceptor pairs were investigated with the aid of the steady-state and time-resolved photoluminescence methods. The observed differences in the energy transfer efficiency are not fully explained by the Förster radius, deduced from the spectral overlap calculation. The order of energy transfer efficiencies for different donor/acceptor pairs does not follow the sequence of Förster radius, particularly for the acceptors having relatively long PL lifetimes. Hence, an alternative simple model is proposed to account for the order of energy transfer efficiency, which is to include the effect of the acceptor PL lifetime, specifically in the presence of excess donor. Such is the case with usual polymer LED devices.