Air-stable Organic Field-Effect Transistors based on a Heterotriangulene Polymer
Kerstin Schmoltner
Schmoltner,1 Florian Schlütter,2 Milan Kivala,2 Martin Baumgarten,2 Stefanie Winkler,3,4 Roman Trattnig,1 Norbert Koch,3,4 Andreas Klug,1 Emil J. W. List1,5 and
15:20 - 17:30 Thursday 24 October 2013 Foyer Alte Technik The fast progress in research on novel small molecule and π-conjugated polymer based organic semiconductors contributed to successful realizations of simple electronic circuits for low-cost radiofrequency identification tags, flexible large-area displays, as well as for sensor applications. In particular, π-conjugated polymers with their outstanding solution-processability proved to be suitable candidates with good electric properties in organic field-effect transistors, i.e. high charge carrier mobilities, high on/off ratios and low threshold voltages, enabling cost-effective, simple large-scale production. Since most of these large-scale roll-to-roll printing techniques are applied under ambient conditions, air-stability of organic semiconductors is required as well.
In this context we report on a novel air-stable heterotriangulene polymer (PTA) as an active layer in bottom-gate/bottom-contact p-channel organic field-effect transistors (OFETs). The newly synthesized amorphous organic semiconductor was thoroughly characterized concerning morphological, optical, electrical and interface related properties by x-ray diffraction, atomic force microscopy, UV/Vis-absorption, photoluminescence as well as ultraviolet photoelectron spectroscopy. This novel bridged triarylamines with its amorphous microstructure exhibited a saturation mobility of ~4.2 x10-3 cm2V-1s-1 and an on/off current ratio of ~105. The influence of several surface treatments was studied in order to optimize the performance on silicon dioxide substrates. Moreover, we show that the utilization of chloroform as solvent leads to a protonation of the nitrogen atom on the PTA polymer, which has a significant influence on the electrical characteristics of OFETs. Finally, the ambient stability of PTA OFETs over months is benchmarked against P3HT OFETs.
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