We report the synthesis and characterization of a cross-linkable, cinnamic acid functionalized, hole-transporting polyfluorene–triarylamine (PF–PTAA) copolymer. Irradiation with light induces [2 + 2] cycloaddition and renders thin films of this polymer insoluble. Spin-coated films of the polymer and their light-induced cross-linking were investigated by atomic force and electron microscopy. In a proof-of-principle multilayer OLED device the polymer was applied as hole-transport layer (HTL) with commercially available F8BT as emitting layer (EML). Compared to the reference device without HTL we observe a significant increase in OLED performance. These results promise progress in cost-effective large area fabrication of polymer-based multilayer OLEDs with superior performance.

The performance of polymer field-effect transistors (PFETs) based on short rigid rod semiconducting poly(2,5-didodecyloxy-p-phenyleneethynylene) (D-OPPE) is highlighted. The controlled heating and cooling of thin films of D-OPPE allows for a recrystallization from the melt, boosting the performance of D-OPPE-based transistors. The improved film properties induced by controlled annealing lead to a hole field-effect mobility around 0.014 cm V s , an on/off ratio of 10 , a sub-threshold swing of 3 V dec and a threshold voltage of -35 V, employing a poly(methyl methacrylate) (PMMA) gate dielectric. Thus, PFETs out of D-OPPE compete now with spin-coated, polycrystalline poly(3-hexylthiophene)-based PFETs.

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