n-Type Ultrathin Few-Layer Nanosheets of Bi-Doped SnSe: Synthesis and Thermoelectric Properties AITranslate

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DOI：https://doi.org/10.1021/acsenergylett.8b00399

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SnSe, an environmentally friendly layered chalcogenide, has fostered immense attention in the thermoelectric community with its high thermoelectric figure of merit in single crystals. Although the stride toward developing superior p-type SnSe as a thermoelectric material is progressing rapidly, synthesis of n-type SnSe is somewhat overlooked. Here, we report the solution-phase synthesis and thermoelectric transport properties of two-dimensional (2D) ultrathin (1.2–3 nm thick) few-layer nanosheets (2–4 layers) of n-type SnSe. The n-type nature of the nanosheets initially originates from chlorination of the material during the synthesis. We could increase the carrier concentration of n-type SnSe significantly from 3.08 × 1017 to 1.97 × 1018 cm–3 via further Bi doping, which results in an increase of electrical conductivity and power factor. Furthermore, Bi-doped nanosheets exhibit ultralow lattice thermal conductivity (∼0.3 W/mK) throughout the temperature range of 300–720 K, which can be ascribed to the effective phonon scattering by an interface of SnSe layers, nanoscale grain boundaries, and point defects.