Low-temperature solution-processable electronic materials are of considerable interest for large-area, low-cost electronics, thermoelectrics and photovoltaics. To this end, the formulation of a suitable semiconductor ink is essential. Here we report the two-dimensional (2D) colloidal nanoplates as a new ink material for the assembly of high performance electronic thin films. We show that Bi2Se3 and Bi2Te3 2D nanoplates, with well-controlled thickness (6-15 nm) and lateral dimension (0.5-3 µm), represent an ideal geometry for the assembly of highly uniform continuous thin films with greatly reduced grain boundaries and a full surface coverage, and thus enable solution-processed electronic thin films with unprecedented performance including a room temperature carrier mobility &gt;100 cm2 v-1 s-1. Besides, we demonstrate a co-solvent approach using binary mixture solvent of amine and thiol , which is much safer than hydrazine, for effective dispersion and dissolution of a large number of inorganic semiconductors including Cu2S, Cu2Se, In2S3, In2Se3, CdS, SnSe and others. Such ink material can be readily processed into high performance semiconducting thin films (Cu2S and Cu2Se) with the highest room temperature conductivity among all solution-based materials. The low-temperature solution processed Cu2S and Cu2Se thin films exhibit comparable thermoelectric performance with that obtained from high tempature method. In the other hand, we demonstrate the first solution-phase symmetry-mismatched epitaxial growth of square PbSe (001) on hexagonal (0001) plane of Bi2Se3 nanocrystal in a mild condition (&lt; 200 oC). Furthermore, the prepared PbSe/Bi2Se3 heterostructure exhibits a remarkably reduced thermal conductivity and an improved figure-of-merit compared with pristine Bi2Se3 nanoplate, majorly resulting from the efficient phonon scattering on the interface. Our study demonstrates a new epitaxy mode by an affordable approach and offers alternative means to engineer the interface within composite materials to enable high-performance thermoelectric devices.

Solution-processed semiconductor materials for electronic and thermoelectric devices

251st National Meeting (2016)

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