Bi2Te3热电材料研究现状

Bi2Te3热电材料是半导体材料,室温下具有良好的热电特性,能够实现热能和电能的相互转化,应用前景十分广阔。Bi2Te3热电材料的转换效率低是影响其应用的瓶颈之一,目前世界范围内的研究热点主要集中在如何提高热电材料的能量转换效率上。综述了热电材料的种类、国内外关于Bi2Te3热电薄膜的制备方法和性能研究,对多种典型制备方法进行分析对比,探讨了影响Bi2Te3热电薄膜质量的因素及机制。结合Bi2Te3热电薄膜在温差发电和热电制冷方面的应用,如果微型热电制冷器实现与大功率LED芯片集成封装,那么芯片级低温散热问题有望解决。     

电场激活压力辅助烧结对(Bi2Te3)0.2(Sb2Te3)0.8热电材料微观结构及热电性能的影响

采用电场激活压力辅助烧结（FAPAS）技术制备了(Bi2Te3)0.2(Sb2Te3)0.8热电材料,采用无电场、低电场强度和高电场强度三种烧结方式作为对比实验,研究了烧结过程中施加电场强度对(Bi2Te3)0.2(Sb2Te3)0.8热电材料微观结构和热电性能的影响。研究结果表明,在烧结过程中施加电场,可明显提高(Bi2Te3)0.2(Sb2Te3)0.8热电材料的电导率和Seebeck系数,从而提高其综合电功率因子;而采用大电场强度烧结则会使(Bi2Te3)0.2(Sb2Te3)0.8材料出现层状结构择优取向,在电性能相对较高的情况下亦使其热导率明显减低,从而获得较高ZT值。     

磁控溅射法制备Bi2Te3热电薄膜的研究

Bi2Te3薄膜是室温下热电性能最好的热电材料,利用磁控溅射在长有一薄层SiO2的n型硅样品上制备Bi/Te多层复合薄膜,经后续退火处理生成Bi2Te3。通过分析Bi2Te3薄膜的生长和退火工艺,探讨Bi/Te中Te的原子数分数对薄膜热电性能的影响。采用XRD和SEM对薄膜的结构、形貌和成分进行分析,并测量不同条件下的Seebeck系数。薄膜Seebeck系数均为负数,表明所制备样品是n型半导体薄膜,且最大值达到-76.81μV.K-1;电阻率ρ随Te的原子数分数增大而增大,其趋势先缓慢后迅速。Bi2Te3薄膜的热电性能良好,Te的原子数分数是60.52%时,功率因子最大,为1.765×10-4W.K-2.m-1。     

低维Bi_2Te_3热电材料的制备与性能研究

用溶剂热法制备了直径在100nm以内的一维针状及厚20～30nm、长几微米的二维花朵状Bi2Te3热电材料,分析了不同形貌产物的生长机理,并对其热电性能进行了比较。结果表明,添加剂的分子结构对产物形貌起决定性作用。不同形貌产物的热电性能随温度变化的机制不同,一维纳米结构Bi2Te3产物的功率因子随温度升高而增加,最大值为143.1μΩ·m–1K–2。而二维纳米结构的Bi2Te3产物虽然在室温附近有较大的Seebeck系数,约100μV/K,但由于其电导率较低,功率因子在较宽的温度范围内保持在23μΩ·m–1K–2左右。     

基于Bi_2Te_3合金材料的热发电模块研究

为了提高Bi2Te3热电材料的性能,采用Bi2Te3纳米粉体前驱物快速熔炼烧结法,制备了在室温条件下具有温度敏感性的Bi2Te3合金材料,在425K时此材料的热电优值达到0.548。在此基础上,研制了热电模块,并对其性能进行了测试。结果表明,以该Bi2Te3合金材料制备的热发电模块具有良好的伏安特性和稳定的内阻,当热冷端温度分别为140和60℃时,模块的最大输出功率可达到0.39W,显现出潜在的应用前景。     

制备工艺对新型热电材料制冷性能的影响

通过取点法得到了由Ingot法、BM法、S-MS法和Te-MS法制备的四种新型p型热电材料(Bi0.5Sb1.5)Te3的变物性参数拟合公式,分析了温度对不同方法制备的热电材料的影响,得到了热电材料无量纲优值与绝对温度的关系曲线.从热力学方面研究了制备工艺对基于新型热电材料的热电制冷器最大制冷系数的影响.结果表明:由Te-MS法制备的新型p型热电材料(Bi0.5Sb1.5)Te3具有最大的优值系数,基于该材料的热电制冷器最大制冷系数可达2.49,较其他三种方法制备的热电材料分别提升了 34.59％,37.57％和25.76％.     

热电材料的研究进展

随着热电材料与薄膜制备技术和性能研究手段的发展,具有高热电性能的热电薄膜和低维结构受到人们关注。目前,国内外研究主要集中在如何提高热电材料的能量转换率等核心技术问题上。介绍了热电材料的理论背景、材料分类、制备手段和热电性质的表征,其中,制备手段及热电性质表征主要以Bi2Te3基热电材料展开论述。最后,对热电材料的发展和未来研究方向进行总结。     

(Bi2Te3)0.90(Sb2Te3)0.05(Sb2Se3)0.05热压合金微观结构和电学性能相关性研究

通过熔炼,研磨制备N型(Bi2Te3)0．90(Sb2Te3)0．05(Sb2Se3)0．05热电材料的粉末,热压制备混合粉末热压合金。通过SEM和XRD研究热压合金的微观结构,在室温测量热压合金样品的电学性能。结果表明热压合金在微观结构和电学性能上存在各向异性,从而预示能够在增强材料机械强度的同时提高其热电性能。     

反应烧结压力对Bi_2Te_3半导体材料组织与性能的影响

以Bi和Te的单质为原料,用固相反应烧结法制备Bi2Te3P型半导体制冷材料.实验采用X射线衍射仪、莱卡光学显微镜分析压制工艺对材料组织性能的影响.实验结果表明:压力增加,塞贝克系数减少.压力较小时有BiTe存在,压力增加BiTe减少,Bi2Te3增加,300KN时基本为纯Bi2Te3     

Si-Bi2Te3光热耦合电源器件的结构设计与性能

空间近日等强辐照造成的高温严重影响光伏电池的转化效率,同时造成辐射能量的浪费.以单晶Si光伏电池和Bi2Te3热电电池为基本单元,构建Si-Bi2 Te3光热耦合电源器件模型.采用有限元分析法分析特定辐射条件下Si-Bi2Te3光热耦合电源器件的热分布情况,并结合光伏电池与热电电池的温度特性进一步计算了器件的转化效率.结果显示,Bi2Te3热电池的存在一定程度上降低了Si光伏电池的工作温度,在空间环境下Si-Bi2Te3光热耦合电源器件的转化效率相对于单一的Si光伏电池有2％ ～3％的提高.最后讨论了该器件Si光伏电池和Bi2Te3热电池的功率输出方式.     

The Surface Preparation of Thermoelectric Materials for Deposition of Thin-Film Contact Systems

Semiconductors - The method of mechanical treatment of thermoelectric materials Bi2Te2.8Se0.2 (0.14 wt % of CdCl2), Bi0.5Sb1.5Te3 (2 wt % of Te and 0.14 wt % of TeI4), PbTe (0.2 wt % of PbI2 and...     

Correlation between microstructure and drastically reduced lattice thermal conductivity in bismuth telluride/bismuth nanocomposites for high thermoelectric figure of merit

The concept of nanocomposite/nanostructuring in thermoelectric materials has been proven to be an effective paradigm for optimizing the high thermoelectric performance primarily by reducing the thermal conductivity. In this work, we have studied the microstructure details of nanocomposites derived by incorporating a semi-metallic Bi nanoparticle phase in Bi₂Te₃ matrix and its correlation mainly with the reduction in the lattice thermal conductivity. Incorporating Bi inclusion in Bi₂Te₃ bulk thermoelectric material results in a substantial increase in the power factor and simultaneous reduction in the thermal conductivity. The main focus of this work is the correlation of the microstructure of the composite with the reduction in thermal conductivity. Thermal conductivity of the matrix and nanocomposites was derived from the thermal diffusivity measurements performed from room temperature to 150 °C. Interestingly, significant reduction in total thermal conductivity of the nanocomposite was achieved as compared to that of the matrix. A detailed analysis of high-resolution transmission electron microscope images reveals that this reduction in the thermal conductivity can be ascribed to the enhanced phonon scattering by distinct microstructure features such as interfaces, grain boundaries, edge dislocations with dipoles, and strain field domains.     

Materials Based on Solid Solutions of Bismuth Chalcogenides of n-Type Conductivity Prepared by Melt Crystallization in a Liquid

Semiconductors - The microstructure, mechanical, and thermoelectric properties of samples of the n-type Bi2Te3–Bi2Se3 solid-solution samples containing 6, 8, and 10 mol % Bi2Se3, doped with...     

Effects of Heat Treatment on Thermoelectric and Infrared Properties of Bi2Te3 Films

In this work, Bi2Te3 films (250 nm) are fabricated on SiO2/Si substrates by radio frequency (RF) magnetron sputtering at room temperature, and the prepared films are annealed over the temperature range of 200 ℃ to 400 ℃. Crystallinity and electrical properties of the films can be tuned correspondingly. The power factors of Bi2Te3 films of 0.85 W/K2cm to 11.43 W/K2cm were achieved after annealing. The infrared reflectance measurements from 2.5 m to 5.0 m demonstrate that there is also a slight red-shift of the plasma oscillation frequency in the Bi2Te3 films. By means of plasmonic calculations, we attribute the red-shift of absorption peaks to the reduction of carrier concentration and the change of effective mass of Bi2Te3 films with the increased annealing temperature.     

Sequential Evaporation of Bi-Te Thin Films with Controllable Composition and Their Thermoelectric Transport Properties

We report a simplified sequential evaporation route that can deposit compositionally controllable Bi-Te thermoelectric (TE) thin films without the need for a highly controlled facility. Te and Bi granules were used as starting materials, with their ratio being adjusted to obtain Bi-Te films with different compositions and thicknesses. The as-evaporated and annealed films were subjected to structural and morphological analysis, and their transport properties were measured. X-Ray diffraction data revealed multiple phases for most films. Energy-dispersive x-ray spectroscopy showed that the film composition was Te-enriched due to the large vapor pressure difference of Te and Bi. A Bi₂Te₃ single phase was obtained in the annealed films, having nominal composition of BiTe_1.2. The existence of impurity phases, such as Bi₄Te₃ or elemental Te, was found in all the as-evaporated films and in the annealed films with other nominal Te/Bi ratios, which degraded the TE properties of the films by increasing their electrical conductivity and reducing their Seebeck coefficient. A pure Bi₂Te₃ film with nominal Te/Bi ratio of 1.2 exhibited a maximum power factor of 7.9 × 10^?4 W m^?1 K² after annealing at 200°C. This work demonstrated a simple, undemanding, reliable method to deposit Bi-Te-based TE thin films that can be utilized to fabricate low-cost TE microgenerators.     

Bismuth Doping–Induced Stable Seebeck Effect Based on MAPbI3 Polycrystalline Thin Films

In this article, the thermoelectric properties of a Bi‐doped CH₃NH₃PbI₃ (MAPbI₃) perovskite thin film are studied. Bi‐doped MAPbI₃ thin film samples are fabricated, and it is found that Bi doping could greatly enhance the stability and thermoelectric properties of MAPbI₃. The Bi dopant located at the grain boundaries to modify the carrier channel near grain boundaries, which is observed via scanning electron microscopy and atomic force microscopy, efficiently reduces ion migration and facilitates charge transport. In addition, the Bi dopant can also passivate the defects in bulk MAPbI₃, increasing the polarization effect of MAPbI₃ which is demonstrated by the capacitance‐frequency measurement, thus greatly enhancing the mobility of Bi‐doped MAPbI₃. In addition, Bi‐doped MAPbI₃ leads to grain size reduction; the small size effect not only effectively hinders the MAPbI₃'s crystal phase transition from the tetragonal phase to the cubic phase, but it could also make the structure of MAPbI₃ more stable. Especially, the Seebeck voltage variation of Bi‐doped perovskite was less than that of the undoped one, meaning Bi doping would lead to a much more stable state in MAPbI₃ thin films. The results show that Bi‐doped MAPbI₃ is a promising approach to develop high stable thermoelectric and photovoltaic properties in organic–inorganic hybrid perovskite materials.