Abstract
? 2022 Elsevier B.V.Transition metal dichalcogenide monolayers have shown enormous potential in thermoelectric application in recent years. We now focus on the thermoelectric properties of WS2-WSe2 nanoribbons with superlattice (SL) and Janus (JA) structures using first-principles calculations. The WS2, WSe2, SL, and JA nanoribbons with the ribbon width from 5 to 7 have high structural stabilities. All nanoribbon electronic structures are semiconductors and the ribbon width will modify bandgaps. It can be also observed that WS2, SL, and JA nanoribbons with a ribbon width of 5 have the largest carrier mobilities (up to ~500–1400 cm2 V?1 s?1) and relaxation times (up to ~400–600 fs). We further calculate the electronic transport coefficients and discover that the SL and JA nanoribbons with a ribbon width of 5 exhibit the largest power factors as high as ~80 mW m?1 K?2. Afterwards, the minimum lattice thermal conductivities of SL and JA nanoribbons are 0.53 W m?1 K?1 and 0.61 W m?1 K?1, which are suppressed owing to the declining phonon group velocity and phonon lifetime. The maximum ZT values of SL and JA nanoribbons can reach 5.47 and 4.13. This investigation provides a solid evidence for the application of WS2-WSe2 nanoribbons as promising thermoelectric materials.
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