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1.
    
This study reports on the successful synthesis and on the properties of polycrystalline AgPbmSnSe2+m (m = ∞, 100, 50, 25) samples with a rock salt structure. Between ≈160 and ≈400 K, the dominant scattering process of the carriers in this system changes from acoustic phonon scattering in PbSe to ionized impurity scattering in AgPbmSnSe2+m, which synergistically optimizes electrical and thermal transport properties. Thanks to the faint amount of AgSnSe2, the Seebeck coefficient is enhanced by boosting the scattering factor, the electric conductivity is improved by the increase of the concentration of holes coupled to a limited degradation of their mobility, and the total thermal conductivity is reduced by suppressing bipolar thermal conductivity. Therefore, ZT of AgPbmSnSe2+m (m = 50) reaches 1.3 at 889 K. The mechanism suggested in this study opens new paths to improve the thermoelectric performances of other families of materials.  相似文献   

2.
    
The beneficial effect of impurity scattering on thermoelectric properties has long been disregarded even though possible improvements in power factor have been suggested by Ioffe more than a half century ago. Here it is theoretically and experimentally demonstrated that proper intensification of ionized impurity scattering to charge carriers can benefit the thermoelectric figure of merit (ZT) by increasing the Seebeck coefficient and decreasing the electronic thermal conductivity. The optimal strength of ionized impurity scattering for maximum ZT depends on the Fermi level and the density of states effective mass. Cr‐doping in CeyCo4Sb12 progressively increases the strength of ionized impurity scattering, and significantly improves the Seebeck coefficient, resulting in high power factors of 45 μW cm?1 K?2 with relatively low electrical conductivity. This effect, combined with the increased Ce‐filling fraction and thus decreased lattice thermal conductivity by charge compensation of Cr‐dopant, gives rise to a maximum ZT of 1.3 at 800 K and a large average ZT of 1.1 between 500 and 850 K, ≈30% and ≈20% enhancements as compared with those of Cr‐free sample, respectively. Furthermore, this study also reveals that carrier scattering parameter can be another fundamental degree of freedom to optimize electrical properties and improve thermal‐to‐electricity conversion efficiencies of thermoelectric materials.  相似文献   

3.
    
Se‐doped Mg3.2Sb1.5Bi0.5‐based thermoelectric materials are revisited in this study. An increased ZT value ≈ 1.4 at about 723 K is obtained in Mg3.2Sb1.5Bi0.49Se0.01 with optimized carrier concentration ≈ 1.9 × 1019 cm?3. Based on this composition, Co and Mn are incorporated for the manipulation of the carrier scattering mechanism, which are beneficial to the dramatically enhanced electrical conductivity and power factor around room temperature range. Combined with the lowered lattice thermal conductivity due to the introduction of effective phonon scattering centers in Se&Mn‐codoped sample, a highest room temperature ZT value ≈ 0.63 and a peak ZT value ≈ 1.70 at 623 K are achieved for Mg3.15Mn0.05Sb1.5Bi0.49Se0.01, leading to a high average ZT ≈ 1.33 from 323 to 673 K. In particular, a remarkable average ZT ≈ 1.18 between the temperature of 323 and 523 K is achieved, suggesting the competitive substitution for the commercialized n‐type Bi2Te3‐based thermoelectric materials.  相似文献   

4.
    
p‐Type elemental tellurium (Te) has been found to be a promising thermoelectric (TE) material due to its high band degeneracy near the valence band maximum, and has exhibited a high zT ≈ 1.0 above 600 K. However, when forming Te1−xSex solid solutions, the maximal zTs are reduced because of the severely decreased carrier concentration. It is demonstrated that Se alloying is beneficial for enhancing TE performance of elemental Te provided the carrier concentration is optimized. Through Se alloying, the lattice thermal conductivity is remarkably suppressed by the induced large mass and strain field fluctuation, while the power factor can be maintained at a relatively high value as a result of the moderate alloying scattering potential, the unchanged density‐of‐state effective mass, and the optimized carrier concentration in Te1−xSex alloys. Notably, a positive temperature dependence of carrier mobility is observed near room temperature in Te1−xSex, which is proven to be caused by grain boundary scattering. A maximal zT ≈ 1.05 at 625 K is realized in Te0.93Se0.04As0.03 alloys, about 9% higher than the Se‐free Te. The conversion efficiency between 300 and 625 K is also improved ≈18% via Se alloying.  相似文献   

5.
    
n-type Mg3(Sb, Bi)2 has excellent room temperature thermoelectric performance, which is, however, severely restricted by the negatively charged Mg vacancies that significantly deteriorate the carrier mobility. Herein, by manipulating the threshold solubility and defect formation energy of Mn, multivalent Mn is selectively introduced that synergistically promotes the carrier conduction according to different Mg chemical potentials; In Mg-rich areas, interstitial Mn dominates which effectively reduces the migration and accumulation of Mg vacancies, while in Mg poor areas, interstitial Mn switches to substitutional sites that directly compensate for the negative charge. All the Mn centers possess Jahn–Teller inactive positions, leading to an ultra-stable room temperature thermoelectric performance with a leading ZT up to 0.97. This work reveals the critical effect of multivalent and multifunctional transition metal incorporation in Mg3(Sb, Bi)2-based alloys toward high room-temperature thermoelectric performance.  相似文献   

6.
    
Bi2Te3-based devices have long dominated the commercial market for thermoelectric cooling applications, but their narrow operating temperature range and high cost have limited their possible applications for conversion of low-grade heat into electric power. The recently developed n-type Mg3Sb2-based compounds exhibit excellent transport properties across a wide temperature range, have low material costs, and are nontoxic, so it would be possible to substitute the conventional Bi2Te3 module with a reliable and low-cost all-Mg3Sb2-based thermoelectric device if a good p-type Mg3Sb2 material can be obtained to match its n-type counterpart. In this study, by comprehensively regulating the carrier concentration, carrier mobility, and lattice thermal conductivity, the thermoelectric performance of p-type Mg3Sb2 is significantly improved through Na and Yb doping in Mg1.8Zn1.2Sb2. Moreover, p- and n-type Mg3Sb2 are similar in terms of their coefficients of thermal expansion and their good performance stability, thus allowing the construction of a reliable all-Mg3Sb2-based unicouple. The decent conversion efficiency (≈5.5% at the hot-side temperature of 573 K), good performance stability, and low cost of this unicouple effectively promote the practical application of Mg3Sb2-based thermoelectric generators for low-grade heat recovery.  相似文献   

7.
    
Strain engineering is demonstrated to effectively regulate the functionality of materials, such as thermoelectric, ferroelectric, and photovoltaic properties. As the straightforward approach of strain engineering, epitaxial strain is usually proposed for rationally manipulating the electronic structure and performances of thermoelectric materials, but has rarely been verified experimentally. In this study, tunable and large epitaxial strains are demonstrated, as well as the resulting valence band convergence can be achieved in the Mg3Sb2 epi-films with the choice of substrates. The large epitaxial strains up to 8% in Mg3Sb2 films represent one of the most striking results in strain engineering. The angle-resolved photoemission spectroscopy measurements and the theoretical calculations reveal the vital role of epitaxial strain in tuning the crystal field splitting and the band structure of Mg3Sb2. Benefiting from the appropriate manipulation of the crystal field effect via in-plane compressive strain, the valence band convergence is unambiguously discovered in the strained Mg3Sb2 film grown on InP(111) substrate. As a result, a state-of-the-art thermoelectric power factor of 0.94 mWm−1K−2 is achieved in the strain-engineered Mg3Sb2 film, well exceeding that of the strain-relaxed Mg3Sb2. The work paves the way for effectively manipulating epitaxial strain and band convergence for Mg3Sb2 and other thermoelectric films.  相似文献   

8.
Sb2Te3基半导体合金是目前性能较好的热电半导体材料.将材料低维化处理可以获得较块状材料更大的热电优值.通过磁控溅射工艺制备低维Sb2Te3薄膜,并通过AFM、XRD和XPS测试方法对薄膜的成分、薄膜表面以及原子偏析进行表征.通过退火工艺去除薄膜应力,观察退火工艺前后薄膜表面形貌的变化以及退火温度对薄膜表面质量的影响.试验结果表明通过磁控溅射工艺所制备出的Sb2Te3薄膜为非晶态,随着溅射功率增大,薄膜的表面粗糙度增大.退火可使薄膜变为晶态,但是表面粗糙度增大.较大或较小溅射功率下所制备的薄膜其合金成分与合金靶材有较大偏差.  相似文献   

9.
    
The main bottleneck in obtaining high-performance thermoelectric (TE) materials is identified as how to decouple the strong interrelationship between electrical and thermal parameters. Herein, a precise interface modification approach based on the powder atomic layer deposition (ALD) technology is presented to enhance the performance of CuNi alloys. ZnO and Al2O3 layers as well as their combinations are deposited on the surface of powders, typically in 10–100 ALD cycles, and their effects on the TE performance of bulks is thoroughly investigated. The enhancement of the Seebeck coefficient, caused by the energy filtering effect, compensates for the electrical conductivity deterioration due to the low electrical conductivity of oxide layers. Furthermore, the oxide layers may significantly increase the phonon scattering. Therefore, to reduce the resistivity of coating layer, a multilayer structure is deposited on the surface of powders by inserting Al2O3 into ZnO. The accurate microstructure characterization shows that the Al atoms diffused into ZnO and realized the doping effect after pressing. Al diffusion has the potential to increase the electrical conductivity and complexity of coating layers. Compared to pure CuNi, zT increases by 128% due to the decrease in resistivity and stronger phonon scattering in phase boundaries.  相似文献   

10.
    
Deep-level defects in semiconductor materials usually induce carrier trapping and non-radiative recombination. However, defects caused by unintentional contaminants in antimony selenide (Sb2Se3) solar cells have rarely been reported. Herein, the correlation between defect properties and unintentional impurities in the Sb2Se3 absorber is investigated, which is prepared by injection vapor deposition with Sb2Se3 source purities ranging from 99.9% to 99.9999%. The analysis of deep-level transient spectra reveals that an increase in impurity concentration does not result in new defect types. Nevertheless, the higher impurity level causes an increase in both the defect density and the capture cross section of the original defect. To address this challenge, defect engineering is developed to regulate the growth of the Sb2Se3 absorber. This strategy completely suppresses deepest defect states E3, a mixture of intrinsic defect (SbSe) and impurity Si related defect. As a result, the carrier lifetime increases significantly from 0.37 to 3.4 ps. This enables to fabricate Sb2Se3 solar cells with a power conversion efficiency of 10.41%. This work uncovers the characteristics of unintentional contaminant-related defects, and provides a strategy for fabricating highly efficient Sb2Se3 solar cells with low-purity source materials.  相似文献   

11.
    
Thermoelectric cooling materials based on Bi2Te3 have a long history of unsurpassed performance near room temperature. Recently, research into price-competitive Mg3(Bi, Sb)2-based materials are focused on replacing traditional cooling materials. Here, the thermoelectric properties of Mg3.2Bi1.998−xSbxTe0.002Cu0.005 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) polycrystalline compounds are investigated. In all temperature regions, electrical resistivity and Seebeck coefficient are increased with Sb concentration. The electronic transport properties of Sb-alloyed compounds are maximized by synergistically combined band engineering approaches such as band structure change caused by lattice strain, increased electronic density of states, and chemical potential shift, leading to exceptionally high-power factor values of over 3.0 mW m−1 K−2 at room temperature. Furthermore, with increasing Sb content, thermal conductivity values are systematically reduced due to the promotion of alloy scattering of phonons and suppression of the bipolar contribution. Consequently, these multiple approaches significantly enhance thermoelectric performance, resulting in an enhancement of thermoelectric figure-of-merit zT above 1.1 at 348–423 K. Additionally, a zTavg of 1.1 is recorded at 300–450 K, making it an unrivaled value among the reported n-type Mg3Bi2-based thermoelectric materials. Overall, this work demonstrates that Mg3Bi2-based materials are more promising for thermoelectric cooling applications compared to Bi2Te3-based materials.  相似文献   

12.
Sb2O3掺杂对ZnO薄膜光吸收性能的影响   总被引：1，自引：0，他引：1  
采用RF磁控溅射技术制备了Sb2O3掺杂ZnO薄膜,通过X射线光电子能谱仪（XPS）、X射线衍射仪（XRD）和紫外-可见光（UV-Vis）分光光度计研究了Sb2O3对ZnO薄膜结构和光吸收性能的影响。结果表明：Sb2O2的掺杂影响了ZnO的原子和电子状态、晶粒的生长方式和光吸收性能。薄膜中Sb以多种形态存在：替位原子和化合物（Sb2O3、Zn,Sb2O14）等,ZnO呈混晶方式生长;随着Sb含量的增加,其引起的晶格畸变和次晶相的含量逐渐增加;掺杂薄膜在远紫外（UVA）波段的吸收显著增强,UV吸收峰变窄,强度增大,吸收边变得陡峭且向短波方向移动达5nm,在Vis波段的吸收有所增强。  相似文献   

13.
    
ZnO is identified as a potentially attractive n-type oxide thermoelectric material due to its abundance, nontoxicity, and a high degree of stability. However, working with ZnO is challenging due to its high thermal conductivity from its strong ionic bonds and low electrical conductivity due to its low charge concentrations. Here, it is demonstrated that the electrical and thermal transport properties of ZnO can be simultaneously improved via the successful doping of Al and ZnS coating. The ZnS coating in Al-doped ZnO is observed and analyzed through microstructure and spectroscopic studies. The power factor for 1% ZnS-coated Zn0.98Al0.02O is increased to ≈0.75 mW m−1 K−2 at 1073 K, 161% higher than pure ZnO. This enhancement in the power factor can be explained by the aliovalent Al3+ doping and modifications in intrinsic defects, leading to an increased carrier concentration. Interestingly, ZnS coating significantly reduces lattice thermal conductivity to ≈2.31 W m−1 K−1 at 1073 K for 2% ZnS-coated Zn0.98Al0.02O, a 62% decrease over pure ZnO. This large reduction in lattice thermal conductivity can be elucidated based on coherent phonon scattering via Callaway's model. Overall, the figure of merit, zT, increases to 0.2 in 2% ZnS-coated Zn0.98Al0.02O, which is 272% higher than pure ZnO at 1073 K.  相似文献   

14.
    
In recent decades, improvements in thermoelectric material performance have made it more practical to generate electricity from waste heat and to use solid-state devices for refrigeration. However, despite the development of successful strategies to enhance the figure-of-merit zT, optimizing devices for large-scale applications remains challenging. High zT values do not guarantee excellent device performance, and maintaining high zT over a wide temperature range is difficult. Thus, device-level structural optimization is crucial for maximizing overall energy conversion efficiency. Proper interfacial and structure design strategies, including contact layer selection, multi-stage optimization, and size matching for the n- and p-type thermoelectric legs, are necessary for advancing device performance. Additionally, thermal stability issues, device assembly techniques, mechanical properties, and manufacturing costs are crucial considerations for large-scale applications. To achieve actual applications, the thermoelectric community must look beyond simply aiming for high zT values. This article focuses on modules based on n-type Mg3(Sb, Bi)2, one of the most promising commercially available thermoelectric materials, and discusses the influence of various parameters on the modules and on the corresponding device-level optimization strategies.  相似文献   

15.
    
To bring current thermoelectric (TE) materials achievement into a device for power generation, a full understanding of their dynamic behavior under operating conditions is needed. Here, an in operando study is conducted on the high‐performance TE material β‐Zn4Sb3 under large temperature gradient and thermal cycling via a new approach using in situ transmission electron microscopy combined with characterization of the TE properties. It is found that after 30 thermal cycles in a low‐pressure helium atmosphere the TE performance of β‐Zn4Sb3 is maintained with the figure of merit, zT , value of 1.4 at 718 K. Under a temperature gradient of 380 K (T hot = 673 K and T cold = 293 K) operating for only 30 h, zinc whiskers gradually precipitate on the cold side of the β‐Zn4Sb3 leg. The dynamical evolution of Zn in the matrix of β‐Zn4Sb3 is found to be the source that leads to a high zT value by lowering of the thermal conductivity and electrical resistivity, but it is also the failure mechanism for the leg under these conditions. The in operando study brings deep insight into the dynamic behavior of nanostructured TE materials for tailoring future TE materials and devices with higher efficiency and longer durability.  相似文献   

16.
钛酸钡陶瓷中,高温下晶格失氧使晶粒内部氧匮乏。在氧化气氛中烧成,晶界则是富氧环境。缺陷或杂 质在晶界上进一步氧化,产生晶粒中并不存在的缺陷种类。杂质和缺陷在晶界上与晶粒内部有不同的行为。某些在 晶界上被氧化成高价态的缺陷和杂质,在晶粒中不能存在,而在晶界上以亚稳态形式存在。它们在铁电相变点跃迁 回低价稳态,产生电子陷阱,使材料电阻率迅速增大,形成ＰＴＣＲ效应。  相似文献   

17.
    
Antimony sulfide (Sb2S3) has attracted extensive attention due to its excellent photoelectric characteristics, including a high absorption coefficient (α > 104 cm−1) and a suitable bandgap (≈1.7 eV). However, due to its Q1D (quasi-1D) structure, numerous deep-level defects are identified in the Sb2S3 film, limiting the device's performance, and necessitating more efforts to overcome this situation. In this context, an ethanol solvent-assisted chemical bath deposition (S-CBD) strategy, a novel high-quality thin film manufacturing technique is presented that modifies the supersaturation of the precursor solution by varying the boiling point and solvent polarity. This approach enables the effective regulation of the correlation between the crystal nucleation and growth rates, resulting in Sb2S3 films with large grains (≈4.25 µm, 37.5% ethanol), excellent crystallinity, well-oriented structures (TC(211)/TC(020) = 2.39), low defect density, and prolonged carrier lifetimes (τAve ≈ 12.1 ns). Consequently, the final Sb2S3-based solar device (FTO/CdS/Sb2S3/Spiro-OMeTAD/Au) shows significant improvements in both FF (61.63%) and JSC (17.61 mA cm−2), yielding an excellent power conversion efficiency (PCE) of 7.84%. This research gives particular insights into the growth mechanism of high-quality Sb2S3 thin films by CBD method as well as a potential route for enhancing Sb2S3 solar cell performance.  相似文献   

18.
王梦魁  王峻岳 《微纳电子技术》2006,43(4):177-180,189
重点研究了由CdO-SnO2-WO3系列(简称Cd-Sn-W)和CdO-Sb2O3-WO3系列(简称Cd-Sb-W)及由它们共同组成的双基体三相(Cd2Sb2O7,CdSnO3,CdWO4)结构线性敏感陶瓷的制备方法。给出了上述半导体陶瓷的电子转移式;分析了半导相Cd2Sb2O7和CdSnO3的导电机理和电阻-温度(R-T)曲线呈线性的机理,并对其他相关特性进行了分析和研究。独立地设计了用化学共沉淀方法制备上述NTC(负温度系数)陶瓷微粉的化学反应方程式,并对聚乙二醇和无水乙醇在制备纳米微粉时所起的防止颗粒发生团聚现象的作用进行了分析。由于大分子量的聚乙二醇几乎是无毒的,对人体基本无毒害作用,因而有广泛的推广价值。  相似文献   

19.
    
The increase of the band gap in Zn1‐xMgxO alloys with added Mg facilitates tunable control of the conduction band alignment and the Fermi‐level position in oxide‐heterostructures. However, the maximal conductivity achievable by doping decreases considerably at higher Mg compositions, which limits practical application as a wide‐gap transparent conductive oxide. In this work, first‐principles calculations and material synthesis and characterization are combined to show that the leading cause of the conductivity decrease is the increased formation of acceptor‐like compensating intrinsic defects, such as zinc vacancies (VZn), which reduce the free electron concentration and decrease the mobility through ionized impurity scattering. Following the expectation that non‐equilibrium deposition techniques should create a more random distribution of oppositely charged dopants and defects compared to the thermodynamic limit, the paring between dopant GaZn and intrinsic defects VZn is studied as a means to reduce the ionized impurity scattering. Indeed, the post‐deposition annealing of Ga‐doped Zn0.7Mg0.3O films grown by pulsed laser deposition increases the mobility by 50% resulting in a conductivity as high as σ = 475 S cm‐1.  相似文献   

20.
    
Bismuth sulfide (Bi2S3) is a promising thermoelectric material with earth-abundant, low-cost, and environment-friendly constituents. However, it shows poor thermoelectric performance due to its extremely low electrical conductivity derived from the low electron concentration. Here, a high-performance Bi2S3-based material is reported to benefit from the Fermi level tuning by Ag and Cl co-doping and defect engineering by introducing dense low-angle grain boundaries. Both Ag and Cl act as donors in Bi2S3, upshifting the Fermi level. This increases the electron concentration without degrading the electron mobility, thereby obtaining improved electrical conductivity. The electron localization function (ELF) contour map indicates that interstitial Ag causes electron delocalization, showing higher electron mobility in Bi2S3. More importantly, dense low-angle grain boundaries block phonon propagation, yielding an ultralow lattice thermal conductivity of 0.30 W m−1 K−1. Consequently, a record ZT value of ≈0.9 at 676 K is achieved in the Bi2Ag0.01S3-0.5%BiCl3 sample.  相似文献   

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