Singlet exciton transfer and fullerene triplet formation in polymer-fullerene blend films

Photoluminescence and transient absorption measurements of poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) and 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C-61 (PCBM) blend films reveal that optical excitation of F8BT results in formation of the singlet and triplet excited states of PCBM. These observations are assigned to rapid (> 10(11) s(-1)) singlet energy transfer from F8BT to PCBM, followed by intersystem crossing to the PCBM triplet state. (c) 2006 American Institute of Physics.