PHOSPHORESCENCE AND DELAYED FLUORESCENCE OF POLY(3-HEXYLTHIOPHENE) FILMS

We report the first observation of long-lived photoluminescence of thi n solid films of poly(3-hexylthiophene). One emission with lambda(max) approximately 826 nm is assigned to phosphorescence (PL(P)) and has a lifetime tau1/e approximately 15 mus; a second long-lived emission is attributed to delayed fluorescence (PL(DF)) since it has the same emi ssion profile as prompt fluorescence (PL(F)). PL(DF) decay is biexpone ntial with lifetimes tau approximately 10(-1) ms and approximately 10( -2) ms. Population of the triplet state via upper excited state transf er is demonstrated to be an efficient route to increasing the intensit y of PL(P) and PL(DF).