π-Stacked polybenzofulvene derivatives as hosts for yellow and red emitting OLEDs

• the electroluminescence properties of new π-stacked polybenzofulvenes are studied
• polybenzofulvenes are compared to PVK as hosts in fully solution processed OLEDs
• one of the polymers shows peculiar ability to envelope the dyes in blends
• this polymer shows better performances with respect to PVK in OLEDs
• the good red and yellow OLED performances are due to low dye microaggregation

A new class of π-stacked polymers possessing interesting charge transport properties is represented by polydibenzofulvene derivatives. We study the electroluminescence properties of three π-stacked polybenzofulvene derivatives and compare them to those of the standard π-stacked poly(N-vinylcarbazole). Solution processable devices using one of these polymers as host with benzothiadiazole based dyes display performances overcoming those of the standard poly(N-vinylcarbazole) host. From a photophysical study, the superior performances of the polybenzofulvene containing a fluorene unit at the position 6 of the indene nucleus are explained to arise from its ability to self-assemble with the dyes in supramolecular organizations that reduce their microaggregation.