Two furan-flanked polymers poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-thienylenevinylene} (PDVFs), with a highly -extended diketopyrrolopyrrole backbone, are developed for solution-processed high-performance polymer field-effect transistors (FETs). Atomic force microscopy and grazing incidence X-ray scattering analyses indicate that PDVF-8 and PDVF-10 films exhibit a similar nodular morphology with the ultrasmall lamellar distances of 16.84 and 18.98 angstrom, respectively. When compared with the reported polymers with the same alkyl substitutes, this is the smallest d-spacing value observed to date. This closed lamellar crystallinity facilitates charge carrier transport. Therefore, polymer thin-film transistors fabricated from as-spun PDVF-8 films exhibit a high hole mobility exceeding 1.0 cm2 V-1 s-1 with a current on/off ratio above 106. After annealing treatment at 100 degrees C in air, the highest hole mobility of PDVF-8-based FETs was significantly improved to 1.90 cm2 V-1 s-1, which is among the highest values of the reported FET devices fabricated from polymer thin films based on this mild annealing temperature. In contrast, long alkyl-substituted PDVF-10 exhibited a relatively low hole mobility of 1.65 cm2 V-1 s-1 mainly resulting from low molecular weight. This work demonstrated that PDVFs would be promising semiconductors for developing cost-effective and large-scale production of flexible organic electronics. (c) 2014 Wiley Periodicals, Inc.