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Bi1−xSbx crystal is one of the best n-type thermoelectric materials below 200 K, but its weak mechanical strength hinders practical applications for deep refrigeration. Herein, we adopted the mechanical enhancement method of hot extrusion to investigate the comprehensive mechanical and thermoelectric properties of Bi0.905Sb0.095. It revealed that reducing the grain size of the matrix and increasing the extrusion ratio can improve the gain size uniformity and mechanical properties. Meanwhile, the thermoelectric performance depends on the texture, grain size, and local composition. The extruded sample prepared by ingot with the high extrusion ratio of 9:1 generated uniform small grains, which resulted in the high bending strength of Bi1−xSbx~130 Mpa and a high power factor of ~68 μW·cm−1·K−2@173 K, as well as the relatively high figure of merit of 0.25@173K. This work highlights the importance of the uniform distribution of the grain size and the compositions for Bi1−xSbx, as well as the required universal key parameter for the hot extrusion method. [ABSTRACT FROM AUTHOR]

At present, the weak thermoelectric and mechanical performance of zone‐melting bismuth telluride alloys cannot support the further improvement of cooling and processing performance of semiconductor refrigeration devices. Here, MnO2 is added into high‐strength Bi0.4Sb1.6Te3 prepared by ball milling method to optimize its thermoelectric transport properties. Via in situ reaction, Sb2O3 nano‐precipitates are formed in the matrix, which also leads to the surplus of Te element. As results, the donor‐like effect is suppressed, thereby increasing carrier concentration and power factor. Besides, volatilization of Te‐rich phases during sintering leaves plentiful nanopores, which together with Sb2O3 nano‐precipitates significantly decrease the lattice thermal conductivity. Eventually, the maximum ZT reaches 1.43 at 75 °C for the Bi0.4Sb1.6Te3+0.01MnO2 sample. On this basis, a 31‐pairs module made of the material and commercial n‐type BiTeSe produces large temperature differences (ΔT) of 70.1, 80.8, and 89.4 K at the hot‐side temperature (Th) of 300, 325, and 350 K respectively, which are highly competitive. The maximum coefficient of performance of 8.6 and cooling capacity of 7 W are achieved when Th is set as 325 K. This excellent progress will promote the further development of bismuth telluride refrigeration modules. [ABSTRACT FROM AUTHOR]

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]

Although the CoSb3-based skutterudite thermoelectric devices have been highly expected for wide uses such as waste heat recovery and space power supply, the limited long-term service stability majorly determined by the degradation of electrode interface obstructs its applications. Here, we built up an effective criterion for screening barrier layer based on the combination of negative interfacial reaction energy and high activation energy barrier of Sb migration through the formed interfacial reaction layer. Accordingly, we predicted niobium as a promising barrier layer. The experimental results show the skutterudite/Nb joint has the slowest interfacial reaction layer growth rate and smallest interfacial electrical resistivity. The fabricated 8-pair skutterudite module using Nb as barrier layer achieves a recorded conversion efficiency of 10.2% at hot-side temperature of 872 K and shows excellent stability during long-time aging. This simple criterion provides an effective guidance on screening barrier layer with bonding-blocking-conducting synergetic functions for thermoelectric device integration. Long-term service stability of thermoelectric devices is one of the major obstacles for their application. Here, the authors combine interfacial reaction energy and Sb migration activation energy barrier as a criterion to determine the interfacial reliability for skutterudite thermoelectric devices. [ABSTRACT FROM AUTHOR]

GeTe-based compounds have been intensively studied recently due to their superior thermoelectric performance, but their real applications are still limited so far due to the drastic volume variation that occurs during the rhombohedral–cubic phase transition, which may break the material or the material/electrode interface during service. Here, superior performance and high service stability for GeTe-based thermoelectric compounds are achieved by co-doping Mg and Sb into GeTe. The linear coefficient of thermal expansion before phase transition is greatly improved to match that after phase transition, yielding smooth volume variation around the phase transition temperature. Likewise, co-doping (Mg, Sb) in GeTe successfully tunes the carrier concentration to the optimal range and effectively suppresses the lattice thermal conductivity. A peak zT of 1.84 at 800 K and an average zT of 1.2 in 300–800 K have been achieved in Ge0.85Mg0.05Sb0.1Te. Finally, a Ni/Ti/Ge0.85Mg0.05Sb0.1Te thermoelectric uni-leg is fabricated and tested, showing quite good service stability even after 450 thermal cycles between 473 K and 800 K. This study will accelerate the application of GeTe-based compounds for power generation in the mid-temperature range. [ABSTRACT FROM AUTHOR]

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]

• The power density is higher than other thin-film thermoelectric generator. • Substrate with unique structure resulted in increase of both output voltage and the maximum output power. • A comprehensive 3D simulation with variable parameter was developed. [Display omitted] Thermoelectric generators can be used as energy harvesting for power supply in Internet of Thing sensors. Here, material properties and geometry parameters were investigated to improve the annular thin-film thermoelectric generator (ATTEG) output performances. The as-deposited and annealed n-type Bi 2 Te 2.7 Se 0.3 and p-type Bi 0.5 Sb 1.5 Te 3 were deposited by radio frequency magnetron sputtering which resulted in higher Seebeck coefficient and electrical conductivity of annealed thin films. The temperature distributions and output performances in ATTEG were calculated using numerical simulation to identify the geometry parameters. The results showed that thinner substrate with higher output performances, larger legs number with higher output voltage, and a peak point in the maximum output power was observed for the effect of the angle ratio of p-type leg to n-type leg with optimal value of 1. We fabricated ATTEGs with different TE legs to identify the machining accuracy, and the ATTEG with 12 legs resulted in output voltage of 27.7 mV, the maximum output power of 169.0 nW and power density of 127.39 n W ∕ cm 2 at a temperature difference of 23 K. Hollowing and nicking on substrate were proposed as further improvement, and resulted in increasement of 6.6% in output voltage and 13.6% in the maximum output power. [ABSTRACT FROM AUTHOR]