School of Physics, CRANN & AMBER Research Centres, Trinity College Dublin, Dublin D02 E8C0, Ireland.
ACS Nano. 2023 Feb 14;17(3):2912-2922. doi: 10.1021/acsnano.2c11319. Epub 2023 Jan 31.
The investigation of high-mobility two-dimensional (2D) flakes beyond molybdenum disulfide (MoS) 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) and tungsten disulfide (WS) as well as MoS 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 ≈ 11 cm V s, μ ≈ 9 cm V s, and μ ≈ 2 cm V s with a current on/off ratios of / ≈ 2.6 × 10, 3.4 × 10, and 4.2 × 10 for MoS, WS, and WSe, 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 transistors is maintained on polyethylene terephthalate (PET) even after 1000 bending cycles at 1% strain.
为了创建一个符合衬底且能在数千个弯曲循环中保持功能的高迁移率溶液处理网络库，除了二硫化钼（MoS）之外，对二维（2D）高迁移率薄片的研究将是必要的。在这里，我们报告了电化学剥离大纵横比（>100）的半导体二硒化钨（WSe）和二硫化钨（WS）以及 MoS 薄片，作为比较。我们使用 Langmuir-Schaefer 涂层来实现高度对齐和共形的薄片网络，在低处理温度（120°C）和无酸处理的情况下，具有最小的介孔率（约 2-5%）。这使我们能够在环境空气中制造电化学晶体管，实现平均迁移率μ≈11 cm V s，μ≈9 cm V s，μ≈2 cm V s，电流比为/≈2.6×10、3.4×10和 4.2×10，分别对应 MoS、WS 和 WSe。此外，我们的晶体管显示出接近约 0.4 V 的阈值电压，亚阈值斜率低至 182 mV/dec，这是保持功率效率的重要因素，代表了现有技术的一个数量级的改进。此外，我们的 WSe 晶体管在聚对苯二甲酸乙二醇酯（PET）上的性能在 1%应变下经过 1000 次弯曲循环后仍能保持。
