Nondilute 1,2-dichloroethane solution of poly(9,9-dioctylfluorene-2,7-diyl): A study on the aggregation process

Molecular aggregates in conjugated polymer (CP) solution can propagate into mesoscale morphology of the relevant film and further dominate the optoelectronic property. Herein, we probed the aggregation behavior of poly(9,9- dioctylfluorene-2,7-diyl) (PFO) and studied its influence on the photophysical property in 1,2-dichloroethane (DCE) solution, where the contents of β-phase or -aggregates increased with prolonged aging time. Thereinto, high quality β-film was fabricated from DCE solution with critical aggregate time of 6 min. The film exhibited excellent surface morphology and characteristic emission of β-phase. Meanwhile, films prepared from aged DCE solutions exhibited high crystallinity, which was promising to obtain higher photoluminance efficiency and charge transport ability simultaneously. Therefore, it is significant to get deep insight into the aggregation behavior of CP, which is involved not only with the solution-processing technology of plastic device, but also with the optoelectronic property of CP.