Weak interlayer interactions and nearly temperature independent electrical transport in p-type 1T′-MoTe2/Sb2Te3 superlattice-like films

Abstract

Thermoelectric superlattices (SLs) are one of the important focuses in the thermoelectric field due to their ordered stacking structure and the potential to obtain extremely high thermoelectric performance. To understand the critical effects of interlayer interactions, this work fabricates p-type (1T′-MoTe2)x(Sb2Te3)y SLs and investigates their electrical properties as functions of SL period and temperature. The results discovered that the weak interlayer interactions could be driven by both the small work function difference and temperature. This brings forth hole donation and energy filtering and leads to increased hole density and the carrier effective mass of (1T′-MoTe2)x(Sb2Te3)y SLs. Strikingly, the SL structure is beneficial for achieving temperature independent electrical properties, owing to the temperature driven interlayer interaction. Several SLs acquire the largest average power factor among all SLs, which is about 1.10 mWm−1K−2 within 300∼473 K, favorable for thermoelectric applications near room temperature. This work points out the beneficial effect of the SL structure on obtaining high thermoelectric properties in a wide temperature range.