Monday October 15, 2018

Researchers Develop New Manufacturing Process for 2D Nanosheets

Researchers from UCLA, UT Austin, and Hunan University developed a novel way for making semiconducting nanosheets. The approach involves "electrochemical intercalation of quaternary ammonium molecules into 2-D crystals, followed by a mild sonication and exfoliation process." Among other things, the researchers replaces small lithium ions with larger ions, such as quaternary ammonium, to mitigate undesirable electrical characteristics. The process can be applied to a range of 2D crystals, like MoS2, WSe2, In2Se3, and black phosphorus, while preserving their desirable properties. One major application seems to be the production of flexible displays and electronics, and the researchers say it could reduce the cost of displays in general. The full research paper is available here, for a fee.

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"The most interesting finding of our study is the development of a scalable and low-cost solution-based approach to fabricating high-performance, flexible thin-film transistors (TFTs) and electronic circuits based on 2-D semiconductor ink," Prof. Duan said. "The atomically thin and intrinsically flexible 2-D nanosheets represent attractive building blocks for flexible/wearable electronics, similar to pieces of paper that can be easily bent, folded and flattened." The TFTs that the researchers produced using their MoS2 2-D nanosheet ink showed greatly improved device performance over existing solution-processed MoS2 TFTs, with at least one order of magnitude increase in carrier mobility and three to four orders of magnitude increase in switching ratio. Their new approach is easily scalable with a high yield, enabling complex logic gates and computational circuits that were so far unattainable using other 2-D inks. "The solution-phase fabrication process of flexible TFTs and circuits is intrinsically scalable and cost-effective and can be readily made into the large scale (> m2) when combined with printing approach and industrial roll-to-roll productions," Prof. Duan explained. "TFTs are the fundamental building blocks for many large-area electronic applications, including the well-known TFT-LCD, a liquid-crystal display that uses TFT technology to improve image qualities such as addressability and contrast."

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