Conjugated Organic Polymers: Effect of Morphology and Defects on the emission of Di-alkyl Polyfluorenes

摘要

Polyfluorenes (PFs) are a class of blue emitting conjugated polymers that have been popular for use in polymer light emitting devices (PLEDs). A general problem with this polymer comes from an undesirable green shift in its emission that often occurs upon use in a device. There are two general theories on the origin of this green emission. Early studies of polyfluorenes indicated that the green shift came from interactions between polymer chains within a film, possibly as a result of aggregates or excimers. Other research has shown that the source of the green emission is from carbonyl defects formed during synthesis of the polymer, or induced through photo-oxidation or thermal degradation. Many of these studies have claimed that green emission is caused solely by defects and not by interchain interaction. It is possible that the ordering of polymer chains within a film could enhance the amount of green emission by one of two mechanisms. Increasing order could lead to more efficient energy transfer to defect sites.