Multi-Layer Metallization Structure Development for Highly Efficient Polycrystalline SnSe Thermoelectric Devices

Development of a numerical method for the performance analysis of thermoelectric generators with thermal and electric contact resistance

GeTe Thermoelectrics

The influence of electrical and thermal contact resistance on the efficiency of a segmented thermoelectric generator is investigated. We consider 12 different segmented $p$-legs and 12 different segmented $n$-legs, using 8 different $p$-type and 8 different $n$-type thermoelectric materials. For all systems a universal influence of both the electrical and thermal contact resistance is observed on the leg's efficiency, when the systems are analyzed in terms of the contribution of the contact resistance to the total resistance of the leg. The results are compared with the analytical model of Min and Rowe (1992). In order for the efficiency not to decrease more than 20%, the contact electrical resistance should be less than 30% of the total leg resistance for zero thermal contact resistance, while the thermal contact resistance should be less than 20% for zero electrical contact resistance. The universal behavior also allowed the maximum tolerable contact resistance for a segmented system to be found, i.e. the resistance at which a leg of only the high temperature thermoelectric material has the same efficiency as the segmented leg with a contact resistance at the interface. If e.g. segmentation increases the efficiency by 30% then an electrical contact resistance of 30% or a thermal contact resistance of 20% can be tolerated.

Behavior of a thermoelectric power generation device based on solar irradiation and the earth’s surface-air temperature difference

Thermoelectric materials are special types of semiconductors that function as “heat pumps” and as heat-to-electricity converters. Thermoelectric power generation allows for small size, high reliability, and quiet operation. Efficient thermoelectric-based heat-to-electricity converters require higher performance materials than are currently available. Direct conversion of heat to electricity could be achieved with solidstate devices based on thermoelectric materials. These devices could play an important role in future energy production, conversion, management, and utilization. When a temperature gradient is created across a thermoelectric module, a voltage is generated, owing to the Seebeck effect. This voltage can be used to drive an external load. Currently, there is a strong scientific and technological drive to identify new materials with enhanced thermoelectric figures of merit ZT= (sS/k)T (where s is the electrical conductivity, S the thermopower or Seebeck coefficient, k the thermal conductivity, and T the temperature). The numerator sS is called the power factor PF. Several classes of materials are currently under investigation, including complex chalcogenides, doped PbTe and its solid solutions, such as Pb1 xSnxTe, [5,6] superlattice thin films, and quantum-dot superlattices. Also of interest are skutterudites, metal oxides, and intermetallic clathrates. The superlattice thin-film structures of Bi2Te3/Sb2Te3 grown from chemical vapor deposition, and of PbSe0.98Te0.02/PbTe formed by molecular beam epitaxy (MBE) have figures of merit greater than ZT= 2 (at approximately 300 and 550 K, respectively). The MBE-grown thin films PbSe0.98Te0.02/PbTe are n-type materials and contain pyramid-shaped “nanodots” of PbSe of uniform size (approximately 20 nm), which form spontaneously inside a matrix of PbTe. Because energyconversion applications require materials in large quantities, we seek bulk analogues of these systems with similar figures of merit. A recent contribution to these efforts was the discovery of the n-type Ag-based tellurides AgSbTe2/PbTe, which can exhibit high figures of merit (ZT 1.7 at 700 K) when properly doped. To construct a fully functioning optimal thermoelectric device, both nand p-type materials are needed. To date, there is no p-type counterpart to AgSbTe2/ PbTe with similar performance. The highest figure of merit reported for p-type bulk materials (ZT 1.2 at 700 K) is exhibited by the so-called TAGS system (based on Te, Ag, Ge, and Sb: (GeTe)1 x((Ag2Te)1 y(Sb2Te3)y)x). [23] These Ge-containing materials, though more efficient than PbTe, have found limited use, owing to their high cost and to a lowtemperature phase transition. Recently, we described the ptype materials Ag(Pb1 ySny)mSbTe2+m, which show outstanding thermoelectric properties, reaching a maximum figure of merit of ZT 1.45 at 630 K. Herein, we report that the Ag-free system Na1 xPbmSbyTem+2, with appropriate combinations of m, y, and x, achieves record-high ZT values for a p-type bulk thermoelectric material. The effect of the composition on the thermoelectric properties is profound. We show that the high performance of these materials derives mainly from a low thermal conductivity. High-resolution transmission electron microscopy (HRTEM) demonstrates pervasive nanostructuring in Na1 xPbmSbyTem+2, which may be the root cause for the remarkably low thermal conductivity. The Na1 xPbmSbyTem+2 system was selected for study because it should be naturally prone to create Na,Sb-rich clusters in the lattice. The distribution of Na and Sb ions in the Pb sublattice cannot be random, as would be demanded by a solid solution, because Coulombic forces alone tend to drive the system to clustering at the nanoscale, thereby lowering the overall energy. The results described herein are in agreement with long-standing theoretical predictions that nanostructuring in semiconductors would lead to enhanced thermoelectric figures of merit. The Na1 xPbmSbyTem+2 materials could find applications in devices for power generation from a wide variety of hot sources, for example, vehicle exhausts, coal-burning installations, or electric power utilities. Na1 xPbmSbyTem+2 (y 1) samples (see Supporting Information for synthesis details) exhibit p-type conduction from 300 to 700 K. Ingots with the composition Na0.95Pb19SbTe21 (m= 19, x= 0.05, y= 1) exhibit an electrical conductivity of s= 1422 Scm 1 with a positive thermopower of S= 105 mVK 1 at room temperature. This leads to the relatively high power factor of PF= 15.6 mWcm K . The temperature dependence of the electrical conductivity and the thermopower of Na0.95Pb19SbTe21 are shown in Figure 1A. The conductivity decreases with increasing temperature, which is consistent with degenerate semiconductors, and reaches s= 150 Scm 1 at 700 K. However, the thermopower increases rapidly to S= 357.6 mVK 1 at 700 K, yielding a much higher power factor of PF= 19 mWcm K . For samples of composition Na0.95Pb20SbTe22 (m= 20, x= 0.05, y= 1), an electrical conductivity of s= 1541 Scm 1 and a [*] Dr. P. F. P. Poudeu, Prof. M. G. Kanatzidis Department of Chemistry Michigan State University East Lansing, MI 48824 (USA) Fax: (+1)517-353-1793 E-mail: kanatzid@cem.msu.edu

This paper reviews recent advancements in integrated thermoelectric power generation and water desalination technologies, driven by the increasing global demand for electricity and freshwater. The growing population and reliance on fossil fuels for electricity generation pose challenges related to environmental pollution and resource depletion, necessitating the exploration of alternative energy sources and desalination techniques. While thermoelectric generators are capable of converting low-temperature thermal energy into electricity and desalination processes that can utilize low-temperature thermal energy, their effective integration remains largely unexplored. Currently available hybrid power and water systems, such as those combining conventional heat engine cycles (e.g., the Rankine and Kalina cycles) with reverse osmosis, multi-effect distillation, and humidification–dehumidification, are limited in effectively utilizing low-grade thermal energy for simultaneous power generation and desalination, while solid-state heat-to-work conversion technology, such as thermoelectric generators, have low heat-to-work conversion efficiency. This paper identifies a key research gap in the limited effective integration of thermoelectric generators and desalination, despite their complementary characteristics. The study highlights the potential of hybrid systems, which leverage low-grade thermal energy for simultaneous power generation and desalination. The review also explores emerging material innovations in high figure of merit thermoelectric materials and advanced MD membranes, which could significantly enhance system performance. Furthermore, hybrid power–desalination systems incorporating thermoelectric generators with concentrated photovoltaic cells, solar thermal collectors, geothermal energy, and organic Rankine cycles (ORCs) are examined to highlight their potential for sustainable energy and water production. The findings underscore the importance of optimizing material properties, system configurations, and operating conditions to maximize efficiency and output while reducing economic and environmental costs.

Abstract

Advancements in thermoelectric materials and their performance for thermoelectric generators (TEGs): A short review

A large-sized thermoelectric module composed of cement-based composite blocks for pavement energy harvesting and surface temperature reducing

Development of a novel cascading TPV and TE power generation system

Thermoelectric generators (TEGs) can significantly improve the net power consumption and battery life of the low power mobile devices or high performance devices by generating power from their waste heat. Recent advancements also show that the ultrathin thermoelectric devices can be fabricated and integrated within a micro-electronic package. This work investigates the power generation by an ultrathin TEG embedded within a micro-electronic package considering several key parameters such as load resistance, chip heat flux, and proximity of the TEG to chip. The analysis shows that the power generation from TEGs increases with increasing background heat flux on chip or when TEGs are moved closer to the chip. An array of embedded TEGs is considered in order to analyze the influence of multiple TEGs on total power generation and conversion efficiency. Increasing the number of TEGs from one to nine increases the useful power generation from 72.9 mW to 378.4 mW but decreases the average conversion efficiency from 0.47% to 0.32%. The average power generated per TEG gradually decrease from 72.9 mW to 42.0 mW when number of TEGs is increased from one to nine, but the total useful power generated using nine TEGs is significant and emphasize the benefits of using embedded TEGs to reduce net power consumption in electronics packages.

Design and optimization of three segmented thermoelectric generator for nuclear reactor application

In the becoming years, energy demand is expected to grow faster than current needs. Thermoelectric technology works through conversion process from heat energy into electricity directly and vice versa. Thermoelectric device that use for energy conversion from heat into electrical is known as thermoelectric generator (TEG). TEG is made of Bismuth Telluride, Lead Telluride and Silicon Germanium compound which contains figure of merit (ZT). In term of applications, TEG is possible to be applied in extreme condition such as a power supply in the space mission, harvesting heat from transportation vehicle, and getting waste heat from industrial sector. Furthermore thermoelectric generation is possible also to be applied as a micro power generation system which is very useful for electrical source for residential installation. In this paper, a brief review of above applications is presented. Early developed research investigation is carried out for application of thermoelectric generator in residential installation by using biomass wooden-fuel stove. The early result shows that there are amount of heat emitted from the side cylinder cook stove as energy waste. There is a chance and possibility to harvest energy waste in the stove to become electric source and finally this related research effort will increase the efficiency of the electric stove in energy conversion.

Mg2Si thermoelectric (TE) elements and modules were fabricated using a commercial polycrystalline Mg2Si source. A monobloc plasma-activated sintering technique was used to fabricate the TE elements and Ni electrodes. The TE modules were composed of n-type Mg2Si, using pin–fin structure elements, in order to achieve simple assembly and to realize stable operation at a temperature of ~800 K. The dimensions of each pin–fin element were 4.2 mm × 4.2 mm × 9.8 mm, and the TE module comprised nine pin–fin elements connected in series. The output characteristics of the pin–fin elements and the TE module were evaluated at temperature differences, ΔT, ranging from 100 K to 500 K. The observed values of open-circuit voltage (V OC) and output power (P) of a single pin–fin element were 98.7 mV and 50.9 mW, respectively, at the maximum ΔT of 500 K. The maximum V OC and P values for the TE module were 588 mV and 174.3 mW, respectively, at ΔT = 500 K.

This study was conducted on design and preparation of the variable compositions bismuth antimony telluride (BiSbTe) alloys by mechanically alloying and the powders sintering to form the thermoelectric alloy materials. The powder of thermoelectric material is coldpressed under 766.4Mpa to make square thermoelectric pairs with size 8.2mm×8.2mm and thicknesses 0.8mm and 1.5mm. The zone melting method was used to acquire P-type thermoelectric material Bi0.4Sb1.6Te3 and N-type thermoelectric material Bi2Te2.55Se0.45. At temperature 381K, the measured Seebeck coefficient of Bi0.4Sb1.6Te3 is 223μV/K, and its thermoelectric figure of merit ZT is 1.36. At temperature 400K, the measured Seebeck coefficient of Bi2Te2.55Se0.45 is 206μV/K, and its thermoelectric figure of merit ZT is 1.03. Solder paste Sn42Bi58 and copper electrode plate are in series connection with 16 pieces of P/N thermoelectric material to form thermoelectric modules. The generating performance of a thermoelectric module is evaluated in terms of its voltage, current and output power of the thermoelectric modules.