Charge-transfer character of excitons in poly[2,7-(9,9-di-n-octylfluorene)(1-x)-co-4,7-(2,1,3-benzothiadiazole)(x)] - Winfield, JM; Van, Vooren A; Park, M-J; Hwang, D-H; Cornil, J; Kim, J-S; Friend, RH (JOURNAL OF CHEMICAL PHYSICS, 2009)