Energy transfer dynamics in polyfluorene-based polymer blends

The Forster energy transfer mechanisms in polyfluorene-based polymer blends have been investigated by picosecond time-resolved photoluminescence spect roscopy. Blends of poly(9,9-dioctylfluorene), (F8), and poly(9,9-dioctylflu oreneco-benzothiadiazole), (BT), ranging from 50% to 0.01% BT have been inv estigated from room temperature down to 12 K. In high concentration BT/F8 f ilms, nearest neighbour transfers from F8 to BT, characterised by an F8 flu orescence lifetime of 12 ps, totally dominate. In low concentration BT/E8 f ilms energy transfer between F8 and BT still occurs at nearest neighbour si tes, but exciton migration to these sites amongst F8 chain segments now als o contributes to the measured dynamics. (C) 2001 Elsevier Science B.V. All rights reserved.