Realizing ranged performance in SnTe through integrating bands convergence and DOS distortion

Abstract

As a typical IV-VI compound, SnTe has aroused widely attentions in the thermoelectric community due its similar crystal and band structures with PbTe. However, both the large number of inherent Sn vacancies and high thermal conductivity result in inferior thermoelectric performance in intrinsic SnTe over a broad temperature. In this work, we successfully improved those disadvantages of SnTe via stepwisely Pb heavily alloying and then In doping. A significantly wide fraction of Pb into SnTe (0–50%) achieves multiple effects: (a) the carrier concentration of SnTe is reduced through decreasing Sn vacancies via alloying high solution Pb atoms in the matrix; (b) the band structure is optimized through promoting the convergence of the two valence bands, simultaneously enhancing the Seebeck coefficient; (c) HAADF-STEM coupled with EDS results illustrate that guest Pb atoms randomly and uniformly occupied Sn atomic sites in the matrix, concurrently strengthening the phonon scattering. Furthermore, we introduced indium into Sn0.6Pb0.4Te system to create resonant states further enlarging the power factors at low-medium temperature. The integration of bands convergence and DOS distortion achieves a considerably high ZTave of ∼0.67 over the wide temperature range of 300–823 K in (Sn0.6Pb0.4)0.995In0.005Te sample.