摘要:
In this work, three diketopyrrolopyrrole-based conjugated small molecular semiconductors characterized by the combination of a diketopyrrolopyrrole (DPP) central core, thiazole pi-conjugated moiety, and dicyanovinyl end group with different alkyl side chain substituents, 2TzDPPA1-2DCV, 2TzDPPA2-2DCV, and 2TzDPPA3-2DCV were synthesized. These small molecules have a similar narrow band gap of about 1.50 eV and deep LUMO energy level at -4.30 eV. Under ambient conditions, electron mobilities of 0.28 cm(2) V-1 s(-1), 0.13 cm(2) V-1 s(-1), 0.25 cm(2) V s(-1) for solution processed thin films of 2TzDPPA1-2DCV, 2TzDPPA2.2DCV, and 2TzDPPA3-2DCV were obtained, due to high crystallinity and well-organized molecular stacking. Compared with the other two materials, thin films of 2TzDPPA1-2DCV enable the best OFET performance with desirable I-on/I-off rates exceeding of 10(7), attribute to the coefficient of smoother film morphology and stronger crystallinity. These results reveal that introducing the thiazole unit into the DPP-based conjugated skeleton is conducive to enhance the crystallinity and tailor LUMO energy levels which ensure good performance and excellent stability of these molecules as active materials for n-channel electronic devices.