Highly efficient pure blue electroluminescence from polyfluorene: Influence of the molecular weight distribution on the aggregation tendency

A dependency between the molecular weight distribution of polyfluorene (PFO) and its aggregation tendency on operation in organic light-emitting devices (OLED) is described. As a result of these findings, low molecular parts of the polymer could be made responsible for the aggregation in liquid crystalline PFO. Consequently, a procedure was developed which leads to PFO-based OLEDs which do not show aggregation on operation anymore but exhibit highly efficient and stable blue electroluminescence.