We report on charge transport and density of trap states (trap DOS) in ambipolar diketopyrrolopyrrole–benzothiadiazole copolymer thin-film transistors. This semiconductor possesses high electron and hole field-effect mobilities of up to 0.6 cm2/V-s. Temperature and gate-bias dependent field-effect mobility measurements are employed to extract the activation energies and trap DOS to understand its unique high mobility balanced ambipolar charge transport properties. The symmetry between the electron and hole transport characteristics, parameters and activation energies is remarkable. We believe that our work is the first charge transport study of an ambipolar organic/polymer based field-effect transistor with room temperature mobility higher than 0.1 cm2/V-s in both electrons and holes.Graphical abstractHighlights► We report on charge transport of high mobility ambipolar transistors. ► The electron and hole mobilities both approach 0.6 cm2/V-s. ► The electron and hole transport properties including mobility, activation energy and trap distributions are very similar.

In this letter, the performance characteristics of single-gate and dual-gate thin-film transistors (TFTs) with amorphous indenofluorene–phenanthrene copolymer semiconductor active layers are reported. Optimized single-gate devices possess mobilities up to 0.15 cm2/V-s and width-normalized contact resistance of 1275 Ωcm. These results were obtained through the combination of a recessed source/drain structure and suitable surface treatments of source/drain contact electrodes. The characteristics of dual-gate indenofluorene–phenanthrene copolymer TFTs with polymer gate insulators are also reported. This structure exhibits increased on-current, reduced threshold voltage, improved sub-threshold swing and increased on–off current ratio compared to single-gate architectures.Graphical abstractHighlights► We report on the electrical characteristics of amorphous copolymer transistors. ► Mobility in excess of 0.1 cm2/V-s was obtained in amorphous organic semiconductor. ► Careful attention was paid to surface treatment of insulator and metal electrodes. ► Dual-gate architectures results in improved sub- and above-threshold characteristics.