High Coefficient of Performance Quantum Well Thermoelectric Nano Cooler

2007 ◽  
Author(s):  
Velimir Jovanovic ◽  
Saeid Ghamaty ◽  
Daniel Krommenhoek ◽  
John C. Bass
Keyword(s):  
Thin Film ◽  
Quantum Well ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Room Temperature ◽  
Single Stage ◽  
Coefficient Of Performance ◽  
High Coefficient ◽  
Temperature Detector ◽  
Good Agreement

Nanotechnology quantum well thermoelectric materials have been developed that have high Figures of Merit and that can attain very high coefficients of performance (COP) to satisfy the requirements for cooling room temperature detectors. Hi-Z Technology, Inc. (Hi-Z) has developed Si/SiGe solid state quantum well (QW) thermoelectric (TE) materials that have demonstrated a Seebeck coefficient and thermoelectric properties that provide >4X higher conversion efficiencies than the current bulk TE materials. With the new Si/SiGe QW materials, cooling systems can be designed that are much smaller, quieter, lighter weight, and that have much reduced power requirements than current TE materials or presently used vapor-compression systems. On-going development for these new QW TE materials has demonstrated high-efficiency TE materials for power generation applications ranging from providing power for wireless sensors to converting waste heat from diesel engine exhaust directly to electricity and thus reducing the load on the alternator and reducing fuel consumption. Now, cooling devices with a high coefficient of performance (COP) are feasible and are being designed for room temperature detector cooling applications. Multi-layer nanocomposite QW films (each 10 nm thick) were fabricated to demonstrate that Si/SiGe QW materials can be deposited on a low thermal conductivity substrate and provide at least the desired COP over the required temperature range of 250K to 350K in a single-stage nano cooler. These QW thermoelectric materials can also be implemented into commercial equipment in the air conditioning and refrigeration applications, thus eliminating fluids, ozone-impacting refrigerants and compressors. Thermoelectric properties of QW thin-film materials have been measured at Hi-Z, several universities and national labs. The conversion efficiency of QW materials has been measured at Hi-Z in two different test couples and in a two-couple device. In all cases, good agreement was obtained between the measurements and prior analytical predictions. Cooling performance was measured in a test with one QW TE element and good agreement was obtained between measurements and analytical predictions. TE properties of the Si/SiGe QW material used in the analysis and design of the subject TE nano cooler were recently independently verified at University of California San Diego (UCSD) and the U.S. National Institute of Standards and Technology (NIST). This paper deals with the analysis of a high COP QW TE single-stage nano cooler for room temperature detectors and with the improved TE properties obtained with the QW thin-film materials resulting in such high COP designs.

scholarly journals Key properties of inorganic thermoelectric materials – tables (version 1)

2022 ◽  
Author(s):  
Robert Freer ◽  
Dursun Ekren ◽  
Tanmoy Ghosh ◽  
Kanishka Biswas ◽  
Pengfei Qiu ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Conversion Efficiency ◽  
Thermoelectric Materials ◽  
Room Temperature ◽  
Temperature Data ◽  
Inorganic Materials ◽  
Peak Performance ◽  
Thermoelectric Conversion ◽  
Wide Range ◽  
Higher Temperature

Abstract This paper presents tables of key thermoelectric properties, which define thermoelectric conversion efficiency, for a wide range of inorganic materials. The 12 families of materials included in these tables are primarily selected on the basis of well established, internationally-recognised performance and their promise for current and future applications: Tellurides, Skutterudites, Half Heuslers, Zintls, Mg-Sb Antimonides, Clathrates, FeGa3–type materials, Actinides and Lanthanides, Oxides, Sulfides, Selenides, Silicides, Borides and Carbides. As thermoelectric properties vary with temperature, data are presented at room temperature to enable ready comparison, and also at a higher temperature appropriate to peak performance. An individual table of data and commentary are provided for each family of materials plus source references for all the data.

scholarly journals Transport properties in nanostructured thermoelectric materials and single crystal perovskites

2021 ◽  
Author(s):  
◽  
Michael Ng
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Single Crystal ◽  
Single Crystals ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Ligand Exchange ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Surface Degradation

<p>Energy consumption worldwide is constantly increasing, bringing with it the demand for low cost, environmentally friendly and efficient energy technologies. One of these promising technologies is thermoelectrics in which electric power is harvested from waste heat energy. The efficiency of a thermoelectric device is determined by the dimensionless figure of merit ZT = σS²T/k where σ is the electrical conductivity, S is the thermopower, k is the thermal conductivity, and T is the average temperature. In this thesis we investigate the use of nanostructuring, which has been known to lead to significant reduction in the lattice thermal conductivity to maximise the figure of merit.  One of the most successful bulk thermoelectric materials is Bi₂Te₃, with a ZT of unity at room temperature. Here we investigate the effects of nanostructuring on the thermoelectric properties of Bi₂Te₃. Sub-100 nm ₂Te₃ nanoparticles were successfully synthesized and the figure of merit was found to be ZT ~ 5X10⁻⁵ at room temperature. The effect of a ligand exchange treatment to replace the long chain organic ligand on the as-synthesized nanoparticles with a short chain alkyl ligand was explored. After ligand exchange treatment with hydrazine the figure of merit of sub-100 nm Bi₂Te₃ was found to increase by two fold to ZT ~ 1X10⁻⁴ at room temperature. Overall the figure of merit is low compared to other nanostructured Bi₂Te₃, this was attributed to the extremely low electrical conductivity. The thermopower and thermal conductivity were found to be ~96 μVK⁻¹ and ~0.38 Wm⁻¹ K⁻¹ at 300 K respectively, which show improvements over other nanostructured Bi₂Te₃.  Further optimisation of the figure of merit was also investigated by incorporating Cu, Ni and Co dopants. The most successful of these attempts was Co in which 14.5% Co relative to Bi was successfully incorporated into sub-100 nm Bi₂Te₃. The figure of merit of nanostructured Bi₁.₇₁Co₀.₂₉Te₁.₇₁ alloy was found to increase by 40% to a ZT ~ 1.4X10⁻⁴ at room temperature. Although overall the figure of merit is low, the effect of Co alloying and hydrazine treatment shows potential as a route to optimise the figure of merit.  A potential novel material for thermoelectrics applications is inorganicorganic perovskite single crystals. Here we report a synthetic strategy to successfully grow large millimetre scale single crystals of MAPbBr₃₋xClx, FAPbBr₃₋xClx, and MAPb₁-xSnxBr₃ (MA = methylammonium and FA = formamidinium) using inverse temperature crystallisation (ITC) in a matter of days. This is the first reported case of mixed Br/Cl single crystals with a FA cation and mixed Pb/Sn based perovskites grown using ITC. The bandgap of these single crystals was successfully tuned by altering the halide and metal site composition. It was found that single crystals of FAPbBr₃₋xClx were prone to surface degradation with increased synthesis time. This surface degradation was observed to be reversible by placing the single crystals in an antisolvent such as chloroform.  A tentative model was proposed to analyse the IV characteristics of the single crystal perovskites in order to extract mobilities and diffusion lengths. The MAPbBr₃ and MAPbBr₂.₅Cl₀.₅ single crystal mobilities were found to be between 30-390 cm² V⁻¹ s⁻¹ and 10-100 cm² V⁻¹ s⁻¹ respectively, the diffusion lengths were found to be between 2-8 μm and 1-4 μm respectively. This is an improvement over polycrystalline thin film perovskites and comparable to other single crystal perovskites. The conductance of MAPb₁-xSnxBr₃ based perovskites was found to increase by 2 orders of magnitude even with just 1% of Sn incorporated. The thermal conductivity of MAPbBr₃ single crystals was found to be ~1.12 Wm⁻¹ K⁻¹ at room temperature which is reasonable low for single crystals, however no other thermoelectric properties could be measured due to the self cleaving nature of the single crystals with decreasing temperature and the high resistivity of the material.</p>

Enhancement of Thermoelectric Properties of P3HT by Addition of Carbon Nanotubes

2019 ◽  
pp. 59-77
Author(s):  
Arif ◽  
Muhammad Tahir ◽  
Hijaz Ahmad
Keyword(s):  
Thin Film ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Renewable Energy ◽  
Thermoelectric Properties ◽  
Material Characterization ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Casting Technique ◽  
Semiconducting Material

In this paper, the enhancement in the thermoelectric properties of the organic semiconducting material, poly(3-hexylthiophene) (P3HT) by addition of carbon nanotubes (CNTs), have been studied for applications in the renewable energy. For this purpose, the thin film of P3HT: CNTs blend has been deposited on the glass substrate by drop casting technique. The blend is prepared by the ratio of 10: 0.5 mg of P3HT: CNTs at room temperature in chloroform. The thickness of P3HT: CNTs nanocomposite found by ellipsometer was 2570 nm. The Seebeck coefficient of the film is measured to be 58.18 mV/K and the electrical conductivity of nanocomposite was 254 S/cm found by four probe method. The bandgap of P3HT: CNTs nanocomposite was 1.4 eV measured by UV-Vis spectrometer. In this blend, the CNTs are used for enhancement of the thermoelectric properties of the film. The films are also characterized by different material characterization techniques. These characterizations are correlated with the thermoelectric properties of the material. The optimized value of the figure of merit (ZT) for the thin film has been achieved ZT = 0.14 for the P3HT: CNTs nanocomposites.

Lanthanide Based Ternary Intermetallics as Advanced Thermoelectric Materials

2006 ◽  
Vol 980 ◽  
Author(s):  
Ken Kurosaki ◽  
Takeyuki Sekimoto ◽  
Kenta Kawano ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Power Factor ◽  
Thermoelectric Materials ◽  
Room Temperature ◽  
Single Phase ◽  
Type Structure ◽  
Large Power

AbstractPolycrystalline ingots of the lanthanide based ternary intermetallics: LaNiSb, GdNiSb, ErNiSb and ErPdSb were prepared and characterized. The thermoelectric properties of ErNiSb and ErPdSb were measured at high temperatures. We succeeded in preparing the single phase ingots of ErNiSb and ErPdSb, while the ingots of LaNiSb and GdNiSb contain appreciable quantities of the impurity phases. ErNiSb and ErPdSb crystallize the MgAgAs-type structure (half-Heusler structure). ErNiSb and ErPdSb indicate positive values of the Seebeck coefficient. The values at room temperature are 36 and 240 micro VK-1 for ErNiSb and ErPdSb, respectively. The electrical resistivity of ErNiSb and ErPdSb decreases with temperature, indicating semiconductor-like behavior. ErPdSb exhibits a relatively large power factor 1.5x10-3 Wm-1K-2 at around 700 K, which is approximately two times larger than that of ErNiSb.

Extremely Low Thermal Conductivity Substances as Novel Thermoelectric Materials

2005 ◽  
Vol 886 ◽  
Author(s):  
Shinsuke Yamanaka ◽  
Ken Kurosaki ◽  
Atsuko Kosuga ◽  
Keita Goto ◽  
Hiroaki Muta
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Room Temperature ◽  
State Of The Art ◽  
Thermoelectric Figure ◽  
Low Thermal Conductivity ◽  
Thallium Compounds ◽  
Thallium Tellurides

ABSTRACTWe have prepared polycrystalline bulk samples of various thallium compounds and measured their thermoelectric properties. The most remarkable point of the thermoelectric properties of the thallium compounds is the extremely low thermal conductivity. The state-of-the-art thermoelectric materials such as Bi2Te3 and TAGS materials indicate relatively low the thermal conductivity, around 1.5 W/m/K. However, the thermal conductivity of the thallium compounds is below 0.5 W/m/K; especially that of silver thallium tellurides is around 0.25 W/m/K at room temperature. This extremely low thermal conductivity leads a great advantage for an enhancement of the thermoelectric performance. In this paper, we report on the properties of some thallium compounds selected for study as novel thermoelectric materials. One of these compounds seems to have a thermoelectric figure of merit comparable to those of state-of-the-art materials.

Fabrication of Bi2Te3 Nanowires Applied in Thermoelectric Generators

2014 ◽  
Vol 609-610 ◽  
pp. 306-310
Author(s):  
Da Hai Ren ◽  
Zhen Heng Yang ◽  
Yi Na Chang ◽  
Zhen Yu Dai ◽  
Zheng You
Keyword(s):  
Thin Film ◽  
Quantum Well ◽  
Aluminum Oxide ◽  
Thermoelectric Properties ◽  
Anodic Aluminum Oxide ◽  
Thermoelectric Generators ◽  
Chemistry Method ◽  
Anodic Aluminum

Compared with block and quantum well thin-film materials, nanowire materials can have better thermoelectric properties and higher merit of ZT values. Electro-chemistry method was used to deposit nanowires in the highly ordered holes of AAO (Anodic Aluminum Oxide). Several conditions were discussed and experimented to determine an appropriate condition for the co-deposition of Bi and Te. Some optimization measures are proposed to obtain more stable fabrication results. Analysis demonstrates that the nanowire grew along the pores from the bottom to the top.

Effects of Al-Doping on the Thermoelectric Properties of ZnO:Al Thin Films

2014 ◽  
Vol 1033-1034 ◽  
pp. 110-113 ◽  
Author(s):  
Jing Ting Luo ◽  
Mao Dong Zhu ◽  
Di Gu ◽  
Liu Yang Wang ◽  
Qing Yun Lin ◽  
...  
Keyword(s):  
Thin Film ◽  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
Zno Films ◽  
Al Alloy ◽  
Al Doping ◽  
Glass Substrates ◽  
Maximum Value ◽  
Alloy Target

Zn1-xAlxO (AZO,x=0, 1.2, 2.1, 2.8 and 3.8 at.%) films were deposited on glass substrates at room-temperature by magnetron sputtering using Zn-Al alloy target. The influence of Al-doping on the thermoelectric properties of AZO films was systematically investigated. It was found that the electrical conductivity at room temperature increased from ~450 S/m (undoped ZnO) to 5.7×104S/m (Zn0.979Al0.021O). The Seebeck coefficient of Zn0.972Al0.028O and Zn0.979Al0.021O film increased stably with the increase of temperature from room temperature up to 300 °C. The power factor of Zn0.972Al0.028O thin film increased significantly with increasing of temperature and reached a maximum value of 17.9×10-5Wm-1K-2at 300 °C, which was about three times larger than that of undoped ZnO films.

A Transient Technique to Measure the Temperature Coefficient of Resistance for Thin Film Resistors

1989 ◽  
Vol 111 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Bahgat Sammakia ◽  
Phillip Vadala ◽  
Thomas Homa
Keyword(s):  
Thin Film ◽  
Temperature Coefficient ◽  
Room Temperature ◽  
Conventional Technique ◽  
Temperature Coefficient Of Resistance ◽  
Moderate Amount ◽  
Transient Technique ◽  
Thin Film Resistors ◽  
Higher Temperature ◽  
Good Agreement

The temperature coefficient of resistance (TCR) is defined as: TCR=(R2−R1)R1×1(t2−t1) where R2 and R1 are the resistances measured at temperatures t1 and t2, respectively. The conventional TCR measurement method consists of measuring resistance at room temperature, then heating the resistor to a known higher temperature, then measuring the resistance again. This technique is very accurate and repeatable, however it is slow and cumbersome because it takes a moderate amount of time for the sample to reach steady state in an oven before the resistance can be measured. The present study proposes a new transient technique for measuring TCR. Thin film resistors are heated by passing a constant electric current through them. At an arbitrarily set time, the resistor temperature is estimated from the known transient conduction solution for a uniform flux surface imbedded in a semi-infinite medium. Measurements of the resistance at that time, along with the resistance at the initial (usually room) temperature will now permit the calculation of TCR. The method was found to be very fast, repeatable, and in good agreement with the conventional technique.

scholarly journals Transport properties in nanostructured thermoelectric materials and single crystal perovskites

2021 ◽  
Author(s):  
◽  
Michael Ng
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Single Crystal ◽  
Single Crystals ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Ligand Exchange ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Surface Degradation

<p>Energy consumption worldwide is constantly increasing, bringing with it the demand for low cost, environmentally friendly and efficient energy technologies. One of these promising technologies is thermoelectrics in which electric power is harvested from waste heat energy. The efficiency of a thermoelectric device is determined by the dimensionless figure of merit ZT = σS²T/k where σ is the electrical conductivity, S is the thermopower, k is the thermal conductivity, and T is the average temperature. In this thesis we investigate the use of nanostructuring, which has been known to lead to significant reduction in the lattice thermal conductivity to maximise the figure of merit.  One of the most successful bulk thermoelectric materials is Bi₂Te₃, with a ZT of unity at room temperature. Here we investigate the effects of nanostructuring on the thermoelectric properties of Bi₂Te₃. Sub-100 nm ₂Te₃ nanoparticles were successfully synthesized and the figure of merit was found to be ZT ~ 5X10⁻⁵ at room temperature. The effect of a ligand exchange treatment to replace the long chain organic ligand on the as-synthesized nanoparticles with a short chain alkyl ligand was explored. After ligand exchange treatment with hydrazine the figure of merit of sub-100 nm Bi₂Te₃ was found to increase by two fold to ZT ~ 1X10⁻⁴ at room temperature. Overall the figure of merit is low compared to other nanostructured Bi₂Te₃, this was attributed to the extremely low electrical conductivity. The thermopower and thermal conductivity were found to be ~96 μVK⁻¹ and ~0.38 Wm⁻¹ K⁻¹ at 300 K respectively, which show improvements over other nanostructured Bi₂Te₃.  Further optimisation of the figure of merit was also investigated by incorporating Cu, Ni and Co dopants. The most successful of these attempts was Co in which 14.5% Co relative to Bi was successfully incorporated into sub-100 nm Bi₂Te₃. The figure of merit of nanostructured Bi₁.₇₁Co₀.₂₉Te₁.₇₁ alloy was found to increase by 40% to a ZT ~ 1.4X10⁻⁴ at room temperature. Although overall the figure of merit is low, the effect of Co alloying and hydrazine treatment shows potential as a route to optimise the figure of merit.  A potential novel material for thermoelectrics applications is inorganicorganic perovskite single crystals. Here we report a synthetic strategy to successfully grow large millimetre scale single crystals of MAPbBr₃₋xClx, FAPbBr₃₋xClx, and MAPb₁-xSnxBr₃ (MA = methylammonium and FA = formamidinium) using inverse temperature crystallisation (ITC) in a matter of days. This is the first reported case of mixed Br/Cl single crystals with a FA cation and mixed Pb/Sn based perovskites grown using ITC. The bandgap of these single crystals was successfully tuned by altering the halide and metal site composition. It was found that single crystals of FAPbBr₃₋xClx were prone to surface degradation with increased synthesis time. This surface degradation was observed to be reversible by placing the single crystals in an antisolvent such as chloroform.  A tentative model was proposed to analyse the IV characteristics of the single crystal perovskites in order to extract mobilities and diffusion lengths. The MAPbBr₃ and MAPbBr₂.₅Cl₀.₅ single crystal mobilities were found to be between 30-390 cm² V⁻¹ s⁻¹ and 10-100 cm² V⁻¹ s⁻¹ respectively, the diffusion lengths were found to be between 2-8 μm and 1-4 μm respectively. This is an improvement over polycrystalline thin film perovskites and comparable to other single crystal perovskites. The conductance of MAPb₁-xSnxBr₃ based perovskites was found to increase by 2 orders of magnitude even with just 1% of Sn incorporated. The thermal conductivity of MAPbBr₃ single crystals was found to be ~1.12 Wm⁻¹ K⁻¹ at room temperature which is reasonable low for single crystals, however no other thermoelectric properties could be measured due to the self cleaving nature of the single crystals with decreasing temperature and the high resistivity of the material.</p>

Attenuated Total Reflection Studies of Honeycomb Nanoporous GaN Thin Films

2015 ◽  
Vol 1108 ◽  
pp. 9-14
Author(s):  
Sook Fong Cheah ◽  
Sai Cheong Lee ◽  
Sha Shiong Ng ◽  
Fong Kwong Yam ◽  
Abu Hassan Haslan ◽  
...  
Keyword(s):  
Thin Film ◽  
Room Temperature ◽  
Guided Waves ◽  
Honeycomb Structure ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Effective Medium Model ◽  
Surface Phonon Polariton ◽  
Atr Spectroscopy ◽  
Good Agreement

In this work, room temperature polarized infrared attenuated total reflection (ATR) spectroscopy was employed to characterize a nanoporous GaN thin film with honeycomb structure. Prominent ATR dips due to the surface phonon polariton (SPP) and guided waves of nanoporous GaN thin film were observed. Both SPP resonance and guided waves were detected in the p-polarized ATR spectrum while only guided waves were detected in the s-polarized ATR spectrum. The ATR results were compared with the theoretical spectra generated by means of effective medium model. Good agreement was achieved between the measured and theoretical spectra. Finally, the thickness and porosity of porous layer were determined unambiguously.

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