Inkjet-printed thin-film transistors using surfactant-based transition-metal dichalcogenide nanocomposites suspended in polymeric semiconductors

Abstract

Ink formulations containing a suspension of single-crystalline molybdenum disulfide (MoS2) nanosheets suspended in the polymeric semiconductor poly(3-hexylthiophene-2,5-diyl) (P3HT) were inkjet printed for the fabrication of thin-film transistors. The MoS2 nanosheets were treated with the surfactant trichloro(dodecyl)silane (DDTS) to functionalize the MoS2 surface and created a more stable suspension, reducing the agglomeration of MoS2 suspended in the P3HT solution. This ink formulation was inkjet printed onto the surface of thermal oxide coated, p+-Si wafers to form common-gate thin-film transistor (TFT) device structures. The printed semiconductor formed the active region of a hybrid MoS2 suspension in P3HT of the TFTs. The field-effect mobility for the hybrid-ink TFTs was found to be three times (3×) higher compared to reference devices using pristine P3HT without the suspension. The functionalized MoS2 suspension was also found to form thinner nanosheet suspensions within the P3HT matrix that resulted in approximately 60% higher field-effect mobility compared to hybrid inks without the surfactant. The enhancement of the electrical properties of the TFTs was determined to be due to a structural change in the thin-film semiconductor. The observed current-voltage (I-V) changes were correlated to measurable structural alterations in the semiconductor thin film characterized by X-ray diffraction, atomic force microscopy, and UV-visible absorption spectroscopy.