Organic small-molecule semiconductors have been widely applied in organic field-effect transistors (OFETs) due to their tunable electronic structures and optoelectronic properties, excellent reproducibility, and facile functionalization. In this work, we designed and synthesized two dithienocoronene diimide (DTCDI)-based small-molecule derivatives—DTCDI-BTMI and its perfluorinated analogue DTCDI-BTMI4F, and systematically investigated the impact of fluorination on the energy levels, thin-film microstructure, and charge transport properties in OFETs. Density functional theory (DFT) calculations revealed that fluorination lowers the LUMO energy (−2.98 eV for DTCDI-BTMI vs. −3.09 eV for DTCDI-BTMI4F), enhancing electron affinity and ensuring favorable HOMO alignment with gold electrodes for efficient charge injection. Especially, the OFET devices based on these two molecules both exhibited ambipolar charge transport characteristics. Under ambient conditions, DTCDI-BTMI demonstrated hole-dominated ambipolar charge transport, with hole and electron mobilities of 1.09 × 10-3 and 2.11 × 10-4 cm2 V-1 s-1, respectively. In contrast, the fluorinated derivative DTCDI-BTMI4F exhibited remarkably enhanced ambipolar transport characteristics, achieving electron and hole mobilities of 1.29 × 10-2 and 2.44 × 10-2 cm2 V-1 s-1, an improvement of one to two orders of magnitude. Furthermore, the nearly balanced hole-to-electron mobility ratio (μh/μe ≈ 1.9) of DTCDI-BTMI4F indicates its highly balanced ambipolar charge transport character. This significant performance enhancement is attributed to the synergistic effects arising from fluorine incorporation, including its strong electron-withdrawing nature, promoted molecular ordering, improved crystallinity, and tighter π-π stacking. This work underscores the considerable potential of the fluorination strategy in designing high-performance ambipolar organic semiconductors.
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