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Low-temperature thermoelectric (TE) materials and devices are gaining traction in the field of heat management for optical communication chips and integrated circuits, owing to their exceptional qualities such as high response speed, precise temperature control, and absence of mechanical moving parts. However, despite several decades of research on TE materials, the focus has primarily been on temperatures above 300 K, and enhancing the performance of low-temperature TE materials remains a huge challenge. With the recent emergence of competitive low-temperature TE materials, such as SnSe, α -MgAgSb, Mg 3 Bi 2 , etc. , it has become imperative to extract universal strategies to improve the performance of TE materials at low temperatures. Consequently, this review aims to comprehensively summarize the working mechanisms of TE devices and uncover the common requirement of high electrical transport for TE material at low temperatures. Additionally, we introduce the fundamental theory and improvement strategies of low-temperature electrical properties. Furthermore, we overview the research progress of low-temperature thermoelectric materials and propose the potential research efforts of single crystal and polycrystal with high texture degree to further enhance their performance. [Display omitted] • Typical refrigeration, heating, and heat dissipation modes of thermoelectric device have been discussed in detail. • The strategies to improve the low-temperature electrical properties have been abstracted. • The research status of traditional and the new rising potential TEC materials based on different working modes are presented. [ABSTRACT FROM AUTHOR]

Lanthanum telluride (La 3- x Te 4) is one of the important candidates of thermoelectric (TE) materials working at high temperatures over 1000 K. However, the thermal stability and oxidation resistance of the TE materials become the crucial issue when they are working at so high temperatures. In this report, it is found that, although La 3- x Te 4 exhibits excellent thermal stability up to 1200 K under inert atmosphere, the existence of oxygen even in very low partial pressure causes serious oxidation and performance degradation at a temperature over 700 K. By introducing metallic nickel particles into La 2.74 Te 4 matrix forming La 2.74 Te 4 /Ni composites, the oxidation rate is greatly reduced both in air and low oxygen partial pressure (Po 2 = 10−3 MPa). The dense La 2 NiO 4 /Ni 2 Te 3 O 8 /NiO oxide composite layer formed during oxidation is in charge of "blocking" the diffusion of oxygen. Dispersing Ni particles gives indistinct influence on the thermoelectric properties leading to a good dimensionless thermoelectric figure of merit as 1.0 at 1273 K in the La 2.74 Te 4 /10 vol.% Ni composite. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Ab-initio calculations of the resonant modes and frequencies for a number of possible fillers in p-type RFe3CoSb12 and RFe4Sb12 were carried out. The results indicate that, although the exact values of fillers’ resonant frequencies in p-type skutterudites are somewhat different from those in n-type Co-based skutterudites, the Einstein-like resonant modes of the fillers are similar to those in n-type materials. Experimentally, several pairs of the fillers were selected and double-filled p-type skutterudite compounds RxMy Fe3CoSb12 (R, M = Ba, Ce, Nd, and Yb) were successfully synthesized. The reduction in the lattice thermal conductivity was realized by extending the range of resonant frequencies. As a result, enhanced ZT values above unity were achieved in these double-filled p-type skutterudites. [Copyright &y& Elsevier]

Thermoelectric transient pulse cooling can break through the limitations of thermoelectric material properties and achieve cooling performance beyond steady-state, which has great potential in active thermal management of high-power electronic devices. However, traditional control strategy for thermoelectric cooler (TEC) under steady cooling modes severely limits the widespread application of pulse cooling. This work focused on the key issue of precise temperature control under ultra-high thermal shock, and developed a novel control strategy composed of PID control, transient pulse control, and feed-forward control. By involving the thermoelectric transient pulse cooling effect, TEC can bear much high thermal load, and feed-forward control can further improve the temperature stability. As a result, the new strategy can bear extreme pulse thermal load as high as 4.59 times of the maximum cooling capacity of the TEC in steady-state within width of 20 ms, and the temperature fluctuation can be suppressed to 0.5 K from 7.58 K by using traditional control strategy based on maximum steady-state cooling capacity. This work demonstrates that the control strategy based on transient pulse cooling can greatly improve the capacity and response speed of thermoelectric cooling, providing important reference for precise temperature control of high-power electronic devices. • A novel control strategy was developed for the transient cooling mode in TEC. • Control strategy based on transient pulse effect realizes higher cooling capacity. • Feed-forward control can improve the temperature control precision. [ABSTRACT FROM AUTHOR]

• Influence of Peltier heat on test accuracy of Transient Electro-thermal is studied. • High accuracy test for thermal conductivity of TE films can be achieved in TPET. • The heat transfer model to measure double-layers film in TPET is established. Accurate and rapid measurement of thermal conductivity of thin films has been a challenge so far in the field of thermoelectric (TE) materials and devices. Herein, we proposed to use a transient photo-electro-thermal (TPET) technique to measure the thermal conductivity of TE thin-films with convenience. Combining theoretical and experimental methods, we found that the TPET technique using laser beam heating can significantly reduce the influence of Peltier effect and thus achieve high test accuracy. The measurement uncertainty of TPET technique for TE films can be depressed below 10%. Furthermore, this method is not only applicable for free-standing thin film, but also for thin film deposited on as-known substrates. Finally, thermal conductivity of several films including p -type Bi 0.5 Sb 1.5 Te 3 , n -type Ag 2 Se, and n -type Bi 2 Te 3 deposited on PI film at different temperature are accurately measured, which demonstrates the wide applicability of TPET technique on semiconductor films. [ABSTRACT FROM AUTHOR]

A novel hybrid film is designed and prepared by in situ growth of ZnO nanoribbons in the interstices of Zn 2 SnO 4 nanoplates network on the compacted woven metal wires through a simple process. The ZnO nanoribbons present in the ZnO/Zn 2 SnO 4 composite film can enhance light harvesting, accelerate electron transport and induce a negative shift in the flat-band potential. Benefiting from its advantageous structure and composition, the ZnO/Zn 2 SnO 4 film can be applied in many fields. For the flexible dye-sensitized solar cells (FDSSCs) employing optimized ZnO/Zn 2 SnO 4 as a photoanode, the conversion efficiency reaches 2.41% corresponding to ∼36.2% improvement relative to the Zn 2 SnO 4 nanoplates-based FDSSCs. Moreover, ZnO/Zn 2 SnO 4 -based FDSSC shows relatively good mechanical stability and long-term stability, retaining 95.1% and 93.3% of its initial efficiency after ten consecutive bending tests and after 15 days under sunlight, respectively; Additionally, the immobilized ZnO/Zn 2 SnO 4 on the metal wires exhibits 96.8% photocatalytic degradation efficiency against an organic dye under UV light, and the photocatalytic performance can be restored almost completely by a simple chemical treatment. More importantly, the in situ growth technique demonstrated in this work can be adopted to fabricate other composite oxides on flexible substrates with high curvature surfaces for additional practical applications in flexible devices. [ABSTRACT FROM AUTHOR]

For enhanced solar energy application, double-layered nitrogen-doped Zn 2 SnO 4 film consisting of bottom nanosheets and top nanoparticles is designed and synthesized on flexible woven metal wires. The effects of doping concentration of nitrogen element (N) and the amount of coating nanoparticles on electronic, optical properties and stability are investigated in detail by various testing techniques. The results show that in the double-layered structure, the nanosheets array can provide direct transport pathways for photoinduced electrons, while the nanoparticles can provide high surface area. On the other hand, doped N element is conducive not only to the absorption of visible light due to narrowed band gap, but also to suppression of charge recombination. With the optimized double-layered N-doped Zn 2 SnO 4 as photoanodes of flexible dye-sensitized solar cells, the corresponding photoelectric conversion efficiency is 2.302% compared to 1.332% and 1.826% in case of pure Zn 2 SnO 4 nanosheets and N-doped Zn 2 SnO 4 nanosheets; The double-layered N-doped Zn 2 SnO 4 is also determined to be high-performance immobilized photocatalyst with a better recyclability for the photodegradation of organic pollutant under sunlight irradiation; More importantly, the preparation methods is also applicable to fabricate other composite oxides on wire-shaped substrate for more practical applications in flexible devices. [ABSTRACT FROM AUTHOR]

Abstract: p-type Sn-doped CoSb3-based skutterudite compounds have been prepared using melting–quenching–annealing method and spark plasma sintering technique. Sn atoms in our samples are completely soluted on Sb-site with a fixed charge state and non-magnetic feature, providing a better choice to ascertain the effect of element doping at the [Co4Sb12] framework on the electrical and thermal transport properties in p-type skutterudites. Doping Sn at the framework introduces additional ionized impurity scattering to affect the electron transport greatly. Similar electrical transport properties between Ce0.2Co4Sb11.2Sn0.8 and Co4Sb11Sn0.6Te0.4 suggest that Ce fillers contribute little to the valence band edge. Filling Ce into the voids and doping Sn at the framework introduce additional phonon resonant and point defect scattering mechanisms, thereby reducing lattice thermal conductivity remarkably. Moreover, our data suggest that combining these two effects is more effective to suppress lattice thermal conductivity through scattering broad range of phonons with different frequencies. [ABSTRACT FROM AUTHOR]