Thermoelectric (TE) materials have been considered as a strong candidate for recovering the waste heat from industry and vehicles due to the ability to convert heat directly into electricity. Recently, multinary diamond-like chalcogenides (MDLCs), such as CuInTe2, Cu2SnSe3, Cu3SbSe4, Cu2ZnSnSe4, etc., are eco-friendly Pb-free TE materials with relatively large Seebeck coefficient and low thermal conductivity and have aroused intensive research as a popular theme in the TE field. In this review, we summarize the TE performance and device development of MDLCs. The features of crystalline and electronic structure are first analyzed, and then the strategies that have emerged to enhance the TE figure of merits of these materials are illustrated in detail. The final part of this review describes the advance in TE device research for MDLCs. In the outlook, the challenges and future directions are also discussed to promote the further development of MDLCs TE materials.
Thermoelectric materials have aroused widespread concern due to their unique ability to directly convert heat to electricity without any moving parts or noxious emissions. Taking advantages of two-dimensional structures of thermoelectric films, the potential applications of thermoelectric materials are diversified, particularly in microdevices. Well-controlled nanostructures in thermoelectric films are effective to optimize the electrical and thermal transport, which can significantly improve the performance of thermoelectric materials. In this paper, various physical and chemical approaches to fabricate thermoelectric films, including inorganic, organic, and inorganic-organic composites, are summarized, where more attentions are paid on the inorganic thermoelectric films for their excellent thermoelectric responses. Additionally, strategies for enhancing the performance of thermoelectric films are also discussed.
The thermoelectric materials have been considered as a potential candidate for the new power generation technology based on their reversible heat and electricity conversion. Lead telluride (PbTe) is regarded as an excellent mid-temperature thermoelectric material due to its suitable intrinsic thermoelectric properties. So tremendous efforts have been done to improve the thermoelectric performance of PbTe, and figures of merit, zT > 2.0, have been reported. Main strategies for optimizing the thermoelectric performance have been focused as the main line of this review. The band engineering and phonon scattering engineering as two main effective strategies are systemically summarized here. The band engineering, like band convergence, resonant levels, and band flatting have been addressed in improving the power factor. Additionally, phonon scattering engineerings, such as atomic-scale, nano-scale, meso-scale, and multi-scale phonon scatterings have been applied to reduce the thermal conductivity. Besides, some successful synergistic effects based on band engineerings and phonon scatterings are illustrated as a simultaneous way to optimize both the power factor and thermal conductivity. Summarizing the above three main parts, we point out that the synergistic effects should be effectively exploited, and these may further boost the thermoelectric performance of PbTe alloys and can be extended to other thermoelectric materials.
Pb-based group-IV chalcogenides including PbTe and PbSe have been extensively studied as high performance thermoelectric materials during the past few decades. However, the toxicity of Pb inhibits their applications in vast fields due to the serious harm to the environment. Recently the Pb-free group-IV chalcogenides have become an extensive research subject as promising thermoelectric materials because of their unique thermal and electronic transport properties as well as the enviromentally friendly advantage. This paper briefly summarizes the recent research advances in Sn-, Ge-, and Si-chalcogenides thermoelectrics, showing the unexceptionally high thermoelectric performance in SnSe single crystal, and the significant improvement in thermoelectric performance for those polycrystalline materials by successfully modulating the electronic and thermal transport through using some well-developed strategies including band engineering, nanostructuring and defect engineering. In addition, some important issues for future device applications, including N-type doping and mechanical and chemical stabilities of the new thermoelectrics, are also discussed.
Thermoelectric materials, enabling the directing conversion between heat and electricity, are one of the promising candidates for overcoming environmental pollution and the upcoming energy shortage caused by the over-consumption of fossil fuels. Bi2Te3-based alloys are the classical thermoelectric materials working near room temperature. Due to the intensive theoretical investigations and experimental demonstrations, significant progress has been achieved to enhance the thermoelectric performance of Bi2Te3-based thermoelectric materials. In this review, we first explored the fundamentals of thermoelectric effect and derived the equations for thermoelectric properties. On this basis, we studied the effect of material parameters on thermoelectric properties. Then, we analyzed the features of Bi2Te3-based thermoelectric materials, including the lattice defects, anisotropic behavior and the strong bipolar conduction at relatively high temperature. Then we accordingly summarized the strategies for enhancing the thermoelectric performance, including point defect engineering, texture alignment, and band gap enlargement. Moreover, we highlighted the progress in decreasing thermal conductivity using nanostructures fabricated by solution grown method, ball milling, and melt spinning. Lastly, we employed modeling analysis to uncover the principles of anisotropy behavior and the achieved enhancement in Bi2Te3, which will enlighten the enhancement of thermoelectric performance in broader materials
