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

Solution-processed electronic inks with two-dimensional (2D) materials have the potential to enable the next generation of low-cost printed digital electronics. [1] Here we will present the advances in fabricating printed complementary inverters achieving a voltage gain |<i>A</i>_v| ≈ 0.1 with liquid phase exfoliated (LPE) flakes and discuss the limitations of the technology. [2] The electrochemical exfoliation of large-aspect-ratio (&gt;100) semiconducting flakes of tungsten diselenide (WSe₂) and tungsten disulfide (WS₂) as well as molybdenum disulfide (MoS₂) will be necessary to create a library of high-mobility solution-processed networks that conform to substrates, remain functional over thousands of bending cycles and can be utilised in complementary solution-processed circuits.<br/><br/>We will present the use of Langmuir–Schaefer coating to achieve highly aligned and conformal flake networks of flakes, with minimal mesoporosity (∼2–5%), at low processing temperatures (120 °C) and without acid treatments. [3] Our processing enables the fabrication of state-of-the-art flexible transistors in ambient air, achieving average mobilities μ &gt; 10 cm²V^–1 s^–1, with a current on/off ratio of I_on/I_off ≈ 10³ - 10⁴. [3] We will also demonstrate subthreshold slopes as low as 182 mV/dec, essential for maintaining power efficiency and examine the performance of our WSe₂ transistors after 1000 bending cycles at 1% strain.[3] Additionally, we will demonstrate air-stable, low voltage (&lt;5 V) operation of inkjet-printed CMOS with MoS₂, with a voltage gain above unity |<i>A</i>_v| ≈ 1.4. [4] The results represent a critical enabling step towards ubiquitous long-term stable, low-cost solution-processed digital integrated circuits.[4]<br/><br/>[1] Torrisi, F. & Carey, T. Graphene, related two-dimensional crystals and hybrid systems for printed and wearable electronics. <i>Nano Today</i> <b>23</b>, 73-96 (2018).<br/>[2] Carey, T. <i>et al</i>. Fully inkjet-printed two-dimensional material field-effect heterojunctions for wearable and textile electronics. <i>Nature Communications</i> <b>8</b>, 1202 (2017).<br/>[3] Carey, T. <i>et al</i>. High-Mobility Flexible Transistors with Low-Temperature Solution-Processed Tungsten Dichalcogenides, <i>ACS Nano</i>, 17, 3, 2912–2922 (2023).<br/>[4] Carey, T. <i>et al</i>. Inkjet Printed Circuits with 2D Semiconductor Inks for High-Performance Electronics. <i>Advanced Electronic Materials</i> <b>7</b>, 2100112 (2021).