Description of exciton transport in a TiO2/MEH–PPV heterojunction photovoltaic material

A model for exciton transport in conjugated polymers has been developed taking into account inhomogeneous broadening of exciton energy level. Time-resolved photoluminescence data were used to determine the parameters of the model, such as exciton lifetime, effective number of exciton energy levels within inhomogeneously broadened density of states, hopping distance and hopping rate constants for excitons. Using the developed model a non-monoexponential decay of photoluminescence of the conjugated polymer deposited on TiO2 substrate was described, and the spectrum of internal quantum efficiency of the heterojunction photovoltaic device based on the conjugated polymer with a nanocrystalline TiO2 layer was predicted.