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 (Vth) 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.