Monolayer MoS2 field-effect transistors patterned by photolithography for active matrix pixels in organic light-emitting diodes

Abstract

Two-dimensional molybdenum disulfide (MoS₂) has substantial potential as a semiconducting material for devices. However, it is commonly prepared by mechanical exfoliation, which limits flake size to only a few micrometers, which is not sufficient for processes such as photolithography and circuit patterning. Chemical vapor deposition (CVD) has thus become a mainstream fabrication technique to achieve large-area MoS₂. However, reports of conventional photolithographic patterning of large-area 2D MoS₂-based devices with high mobilities and low switching voltages are rare. Here we fabricate CVD-grown large-area MoS₂ field-effect transistors (FETs) by photolithography and demonstrate their potential as switching and driving FETs for pixels in analog organic light-emitting diode (OLED) displays. We spin-coat an ultrathin hydrophobic polystyrene layer on an Al₂O₃ dielectric, so that the uniformity of threshold voltage (V_th) of the FETs might be improved. Our MoS₂ FETs show a high linear mobility of approximately 10 cm² V⁻¹ s⁻¹, due to a large grain size around 60 μm, and a high ON/OFF current ratio of 10⁸. Dynamic switching of blue and green OLED pixels is shown at ~5 V, demonstrating their application potential.