Highly Efficient Thin-Film Transistor via Cross-Linking of 1T Edge Functional 2H Molybdenum Disulfides

Thin-film transistors (TFTs) have received great attention for their use in lightweight, large area, and wearable devices. However, low crystalline materials and inhomogeneous film formation limit the realization of high-quality electrical properties for channels in commercial TFTs, especially for flexible electronics. Here, we report a field-effect TFT fabricated via cross-linking of edge-1T basal-2H MoS₂ sheets that are prepared by edge functional exfoliation of bulk MoS₂ with soft organic exfoliation reagents. For edge functional exfoliation, the electrophilic 4-carboxy-benzenediazonium used as the soft organic reagent attacks the nucleophilic thiolates exposed at the edge of the bulk MoS₂ with the help of an amine catalyst, resulting in 1T edge-functional HOOC-benzene-2H basal MoS₂ nanosheets (e-MoS₂). The cross-linking via hydrogen bonding of the negatively charged HOOC of the e-MoS₂ sheets with the help of a cationic polymer, polydiallyldimethylammonium chloride, results in a good film formation for a channel of the solution processing TFT. The TFT exhibits an extremely high mobility of 170 cm²/(V s) at 1 V (on/off ratio of 10⁶) on SiO₂/Si substrate and also a high mobility of 36.34 cm²/(V s) (on/off ratio of 10³) on PDMS/PET substrate.