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The unique layered structure and intrinsically low lattice thermal conductivity of ternary compound PbBi 4 Te 7 have rendered it a promising thermoelectric material. However, the bipolar diffusion effect induced by inherent excitation results in deteriorated Seebeck coefficients and amplified thermal conductivity. In this study, the bipolar diffusion effect of PbBi 4 Te 7 is effectively suppressed through enlarging the bandgap via Se alloying, thereby facilitating its potential application as a complementary counterpart to p-type materials. A maximum ZT value of ∼0.67 is achieved in PbBi 4 (Te 0.7 Se 0.3) 7 at 723 K, signifying an impressive improvement of 121 % compared to pure PbBi 4 Te 7. This study provides a novel insight into enhancing the thermoelectric performance of ternary materials. [ABSTRACT FROM AUTHOR]

PbS has attracted much attention as an excellent thermoelectric material with high development space at middle temperature scope. The thermoelectric performance for n -type PbS was boosted by the cooperative effects of resonance level and Cu dynamic doping in our research. In the first place, In doping improved the electrical transport performance of n -type PbS effectively on account of optimal carrier concentration and resonant level effects, and reduced the lattice thermal conductivity by reason of heightened phonon scattering through impurity atoms scattering simultaneously. Secondly, Cu dynamic doping further increased average power factor to ~18.8 μW cm−1 K−2 at 423 K- 823 K of Pb 0.995 In 0.005 S+3%Cu owing to higher Seebeck coefficients and suppressed electronic thermal transports at vast temperature span. In result, the best thermoelectric figure of merit (ZT) of Pb 0.995 In 0.005 S+3%Cu at 723 K reached ~1.1 and a record large average ZT (ZT ave) of Pb 0.995 In 0.005 S+3%Cu was achieved ~ 0.8 at 423 K-823 K, which is vital in the implementation of thermoelectric technology. Thermoelectric performance of n -type PbS was improved through synergistically integrating In resonant level and Cu dynamic doping. Image 1 • In boosted PF and decreased κ lat due to resonant level and phonon scattering. • Cu suppressed the κ ele effectively and increased average power factor. • High average ZT (ZT ave) ~ 0.8 of Pb 0.995 In 0.005 S+3%Cu at 423 K-823 K was achieved. [ABSTRACT FROM AUTHOR]

N -type PbS have been studied widely for purpose of substituting PbTe attributed to the low price and high earth abundance of sulfur element and it is significant to research the strategy of boosting the thermoelectric performance of PbS through adjusting carrier and phonon transports synergistically. Here, the thermoelectric performance of n -type PbS is enhanced effectively by introducing CaS/SrS. CaS/SrS alloying could simultaneously enhance Seebeck coefficients and reduce lattice thermal transport properties over broad temperature range. As a consequence, the maximum thermoelectric figure of merit (ZT) ~ 1.2 at 930 K and high average ZT (ZT ave) ~0.8 at 423 K–930 K are obtained for n -type PbS+3%CaS/SrS+1%PbCl 2 based materials. These results indicate that the methods of CaS/SrS alloying have great prospect in improving thermoelectric performance of n -type PbS. In this work, the thermoelectric performance of n -type PbS is enhanced effectively by introducing CaS/SrS, which is attributed to high electrical transport properties and the reduced lattice thermal conductivity. The maximum thermoelectric figure of merit ZT ~1.2 at 930 K and high average ZT (ZT ave) ~0.8 at 423 K–930 K can be achieved in n -type PbS+3%CaS/SrS+1%PbCl 2. Image 1 • Alloying CaS/SrS enhanced the power factor of n -type PbS effectively. • The lattice thermal conductivity was reduced remarkably by introducing CaS/SrS. • A high ZT ~1.2 at 930 K was achieved in n -type PbS+3%CaS/SrS+1%PbCl 2. [ABSTRACT FROM AUTHOR]

In this work we investigated the thermoelectric transport behaviors of p -type PbS and n -type PbS with an emphasis on its contrasting electronic band structures. We found that the Seebeck coefficients of p -type PbS increased faster with rising temperature than that of n -type PbS with the same carrier concentration. The Density functional theory (DFT) calculation of the energy band structure of PbS as a function of temperature illustrates a significant contribution from multiple valence bands in K-doped p -type PbS. This work revealed one important information that manipulating electronic bands is also suitable in developing high-performance PbS thermoelectric systems. PbS possesses both multiple conduction bands and multiple valence bands. With rising temperature, valence bands illustrate a more pronounced converging trend than conduction bands, which results in higher Seebeck coefficients in p -type PbS at 523–823 K than that of n -type PbS with the same carrier concentration. Image, graphical abstract [ABSTRACT FROM AUTHOR]