Electronic and Thermoelectric Properties in SnS-Nanoribbon-Based Heterojunctions

Abstract

As an earth-abundant and environmentally friendly material, tin sulfide (SnS) is not only a high-performance photovoltaic material, but also a new promising thermoelectric material. Despite extensive research on the thermoelectric properties of this material in recent years, the room-temperature thermoelectric figure of merit (ZT) of SnS has not been broke through 2 [2022 Sci. China Mater.65 1143]. In this work, based on a combination of density functional theory and non-equilibrium Green’s function method, the electronic and thermoelectric properties in SnS-nanoribbon-based heterojunctions are studied. The results show that although SnS nanoribbons (SNSNRs) with zigzag edges (ZSNSNRs) and armchair edges (ASNSNRs) both have semiconductor properties, the bandgaps of ASNSNRs are much wider than those of ZSNSNRs, which induces much wider conductance gaps of N-ASNSNR (N is the number of tin-sulfide lines across the ribbon width)). In the positive energy region, the ZT peaks of L-SNS-Au are much larger than those of L-SNS-GNR (L represents the number of longitudinal repeating units of SNSNR in the scattering region). While in the positive energy region, the ZT peaks of L-SNS-GNR are larger than those of L-SNS-Au. Further calculations reveal that the figure of merit will be over 3.7 in L-SNS-Au and 2.2 in L-SNS-GNR at room temperature, and over 4 in L-SNS-Au and 2.6 in L-SNS-GNR at 500 K.