Steady state and time-resolved photoluminescence properties of alternating polyfluorene copolymers

We present the photoluminescence properties of two alternating copolymers combining 9,9-di(2'-ethylhexyl)fluorene with a phenylene or a thiophene comonomer, in cyclohexane solution. Their picosecond time-resolved fluorescence decay is fitted to three exponential components. We associate the faster component to a relaxation of the exciton electronic energy and the two slower components to exciton decay at two distinct sites, which we tentatively identify as the central parts of the polymer chains and the chain ends, in view of the relatively short chain lengths.