With emerging flexible and wearable electronics for next-generation display, electronic paper, and health monitoring, high-performance macroelectronics (i.e. integrated electronics over large-area substrates) are required to be integrated on flexible plastic substrates with sufficient performance for necessary computation, storage and communication functions. Organic semiconductors may be readily processed in solution, but typically suffer from relatively low performance and insufficient stability in ambient conditions (heat, oxygen, moisture, etc.). Alternatively, solution-dispersible inorganic nanostructures (e.g., 0D quantum dots or 1D nanowires/nanotubes) have emerged as a unique class of materials that may be processed like organic materials in solution while simultaneously retaining the excellent electronic performance and structural stability of crystalline inorganic materials for high-performance electronics. However the conventional 0D and 1D nanostructures, unfortunately, are typically plagued by surface dangling bonds, chemical disorders, and associated trapping states at the interface, which remain severe challenges to high-performance thin-film electronics. We here define a new concept of van der Waals thin film assembled from solution-processable 2D nanosheets for the fabrication of high-performance large-area electronics. The clean van der Waals interfaces are free of unsaturated dangling bonds and the associated trapping states at grain boundaries that seriously plague the 0D quantum dot or 1D nanowire thin films, and thus promise excellent charge transport for thin-film electronics. In specific, we have successfully assembled van der Waals thin films with superior electronic performance from 2D Bi2Se3, MoS2, and others. For example, the solution-processable Bi2Se3 thin film exhibits an electrical conductivity approaching that in the high-temperature CVD grown sample. Besides, high-quality 2D MoS2 nanosheets based van der Waals thin films were readily processed into large-area TFT arrays with high carrier mobility (~ 10 cm2/(V s) and excellent on/off ratio (~ 106), and, for the first time, enable integrated computational circuits (logic gates and half adder).

Solution-processable van der Waals thin film electronics

2019 Fall National Meeting

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