Synthesis and characterization of phenanthrocarbazole-diketopyrrolopyrrole copolymer for high-performance field-effect transistors.

In this study, we successfully designed and synthesized a novel phenanthro[1,10,9,8- c,d,e,f,g]carbazole ( PCZ)-based copolymer poly[ N-(2-octyldodecyl)-4,8-phenanthro[1,10,9,8- c,d,e,f,g]carbazole- alt-2,5-dihexadecyl-3,6-di(thiophen-2-yl)pyrrolo[3,4- c]pyrrole-1,4(2 H,5 H)-dione] ( PPDPP) with an extended π-conjugation along the vertical orientation of polymer main chain. This polymer exhibited excellent solubility in common solvent and high thermal stability, owning good properties for solution-processed field-effect transistors (FETs). Besides, absorption spectra demonstrated that annealing PPDPP thin films led to obviously red-shifted maxima, indicating the formations of aggregation or orderly π-π stacking in their solid-state films. X-ray diffraction measurements indicated the crystallinity of PPDPP thin films was enhanced after high temperature annealing, which was favorable for charge transport. The solution-processed PPDPP-based FET devices were fabricated with a bottom-gate/bottom-contact geometry. A high hole mobility of up to 0.30 cm2/Vs and a current on/off ratio above 105 had been demonstrated. These results indicated that the copolymers constructed by this kind of ladder-type cores could be promising organic semiconductors for high-performance FET applications. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]