High-Mobility Flexible Transistors with Low-Temperature Solution-Processed Tungsten Dichalcogenides

[Image: see text] The investigation of high-mobility two-dimensional (2D) flakes beyond molybdenum disulfide (MoS(2)) will be necessary to create a library of high-mobility solution-processed networks that conform to substrates and remain functional over thousands of bending cycles. Here we report electrochemical exfoliation of large-aspect-ratio (>100) semiconducting flakes of tungsten diselenide (WSe(2)) and tungsten disulfide (WS(2)) as well as MoS(2) as a comparison. We use Langmuir–Schaefer coating to achieve highly aligned and conformal flake networks, with minimal mesoporosity (∼2–5%), at low processing temperatures (120 °C) and without acid treatments. This allows us to fabricate electrochemical transistors in ambient air, achieving average mobilities of μ(MoS(2)) ≈ 11 cm(2) V(–1) s(–1), μ(WS(2)) ≈ 9 cm(2) V(–1) s(–1), and μ(WSe(2)) ≈ 2 cm(2) V(–1) s(–1) with a current on/off ratios of I(on)/I(off) ≈ 2.6 × 10(3), 3.4 × 10(3), and 4.2 × 10(4) for MoS(2), WS(2), and WSe(2), respectively. Moreover, our transistors display threshold voltages near ∼0.4 V with subthreshold slopes as low as 182 mV/dec, which are essential factors in maintaining power efficiency and represent a 1 order of magnitude improvement in the state of the art. Furthermore, the performance of our WSe(2) transistors is maintained on polyethylene terephthalate (PET) even after 1000 bending cycles at 1% strain.