Suppresing the energy transfer in polymers blends films upon addition of a co-solvent
Materials Letters Vol. 175, Nº -, pp. 248 - 251, July, 2016.
ISSN (print): 0167-577X
Journal Impact Factor: 2,437 (in 2015)
Digital Object Identifier: 10.1016/j.matlet.2016.04.047
Download Full text PDF ( 1 MB)
Energy transfer in conjugated polymer blends is an important process in optoelectronics, with its efficiency very sensitive to the details of phase separation in films. Modification of the relative composition of the blend has been the usual strategy to tune the energy transfer efficiency. In this letter we report on a new approach to switch-off that process: the use of a co-solvent. In particular, we find that the addition of 1,8-diiodooctane to xylene solutions of poly(9,9-dioctylfluorene): poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PFO:F8BT), blends, 99:1 by weight, suppresses the energy transfer in films. This leads to a change from green light-emitting diodes into whitish emitting diodes. This energy transfer suppression is attributed to a stronger phase segregation, with the concomitant formation of larger domains of the two polymers, thereby increasing the distance between energy donor (PFO) and acceptor (F8BT) sites.