Showing papers on "Thermoelectric effect published in 2007"
TL;DR: In this article, the ability to achieve a simultaneous increase in the power factor and a decrease in the thermal conductivity of the same nanocomposite sample and for transport in the same direction is discussed.
Abstract: Many of the recent advances in enhancing the thermoelectric figure of merit are linked to nanoscale phenomena found both in bulk samples containing nanoscale constituents and in nanoscale samples themselves. Prior theoretical and experimental proof-of-principle studies on quantum-well superlattice and quantum-wire samples have now evolved into studies on bulk samples containing nanostructured constituents prepared by chemical or physical approaches. In this Review, nanostructural composites are shown to exhibit nanostructures and properties that show promise for thermoelectric applications, thus bringing together low-dimensional and bulk materials for thermoelectric applications. Particular emphasis is given in this Review to the ability to achieve 1) a simultaneous increase in the power factor and a decrease in the thermal conductivity in the same nanocomposite sample and for transport in the same direction and 2) lower values of the thermal conductivity in these nanocomposites as compared to alloy samples of the same chemical composition. The outlook for future research directions for nanocomposite thermoelectric materials is also discussed.
3,562 citations
TL;DR: The present approach using a 2DEG provides a new route to realize practical thermoelectric materials without the use of toxic heavy elements and enhances the Seebeck coefficient without reducing the electrical conductivity.
Abstract: Enhancement of the Seebeck coefficient (S ) without reducing the electrical conductivity (sigma) is essential to realize practical thermoelectric materials exhibiting a dimensionless figure of merit (ZT=S2 x sigma x T x kappa-1) exceeding 2, where T is the absolute temperature and kappa is the thermal conductivity. Here, we demonstrate that a high-density two-dimensional electron gas (2DEG) confined within a unit cell layer thickness in SrTiO(3) yields unusually large |S|, approximately five times larger than that of SrTiO(3) bulks, while maintaining a high sigma2DEG. In the best case, we observe |S|=850 microV K-1 and sigma2DEG=1.4 x 10(3) S cm-1. In addition, by using the kappa of bulk single-crystal SrTiO(3) at room temperature, we estimate ZT approximately 2.4 for the 2DEG, corresponding to ZT approximately 0.24 for a complete device having the 2DEG as the active region. The present approach using a 2DEG provides a new route to realize practical thermoelectric materials without the use of toxic heavy elements.
850 citations
TL;DR: This perspective outlines a strategy to discover new high zT materials in Zintl phases, and presents results pointing towards the success of this approach.
Abstract: By converting waste heat into electricity and improving the efficiency of refrigeration systems, thermoelectric devices could play a significant role in solving today’s energy problems. Increasing the thermoelectric efficiency (as measured by the thermoelectric material’s figure-of-merit, zT )i s critical to the development of this technology. Complex Zintl phases, in particular, make ideal candidates for thermoelectric materials because the necessary “electron–crystal, phonon–glass” properties can be engineered with an understanding of the Zintl chemistry. A recent example is the discovery that Yb14MnSb11, a transition metal Zintl compound, has twice the zT as the material currently in use at NASA. This perspective outlines a strategy to discover new high zT materials in Zintl phases, and presents results pointing towards the success of this approach.
480 citations
TL;DR: This paper discusses a complementary approach to provide power autonomy to devices on a human body, i.e., thermoelectric conversion of human heat, based on custom-design small-size BiTe thermopiles.
Abstract: Solar cells are the most commonly used devices in customer products to achieve power autonomy. This paper discusses a complementary approach to provide power autonomy to devices on a human body, i.e., thermoelectric conversion of human heat. In indoor applications, thermoelectric converters on the skin can provide more power per square centimeter than solar cells, particularly in adverse illumination conditions. Moreover, they work day and night. The first sensor nodes powered by human heat have been demonstrated and tested on people in 2004-2005. They used the state-of-the-art 100-muW watch-size thermoelectric wrist generators fabricated at IMEC and based on custom-design small-size BiTe thermopiles. The sensor node is completed with a power conditioning module, a microcontroller, and a wireless transceiver mounted on a watchstrap
373 citations
TL;DR: In this article, high performance Bi2Te3 bulk materials with layered nanostructure have been prepared by combining melt spinning technique with spark plasma sintering, and their thermoelectric transport properties are investigated.
Abstract: High performance Bi2Te3 bulk materials with layered nanostructure have been prepared by combining melt spinning technique with spark plasma sintering, and their thermoelectric transport properties are investigated. The electrical conductivity increases greatly and the lattice thermal conductivity decreases significantly with the increase of the roller’s linear speed. These lead to a great improvement in the thermoelectric figure of merit (ZT). The maximum ZT value of 1.35 is obtained at 300K for the sample which is prepared by melt spinning with roller linear speed of 40m∕s. Compared with the zone melting sample, it increases by 73% at the same temperature.
351 citations
TL;DR: In this article, a SPICE compatible equivalent circuit of a thermoelectric module is developed for extracting the parameters of the proposed model from manufacturers' data of thermocoolers (TECs) and TEGs, which can be used to design feedback networks for temperature control applications.
Abstract: The objective of this paper is to develop a SPICE- compatible equivalent circuit of a thermoelectric module. A methodology is developed for extracting the parameters of the proposed model from manufacturers' data of thermoelectric coolers (TECs) and thermoelectric generators (TEGs). The model could be helpful in analyzing the drive requirements of TECs and loading effects of TEGs. The present model is compatible with PSPICE or other electric circuit simulators. An important feature of the model is its ability to generate small-signal transfer functions that can be used to design feedback networks for temperature control applications
337 citations
TL;DR: In this article, the authors calculate the electrical and thermal conductivities and the thermoelectric coefficient of a class of strongly interacting 2+1-dimensional conformal field theories with anti-de Sitter space duals.
Abstract: We calculate the electrical and thermal conductivities and the thermoelectric coefficient of a class of strongly interacting 2+1-dimensional conformal field theories with anti-de Sitter space duals. We obtain these transport coefficients as a function of charge density, background magnetic field, temperature, and frequency. We show that the thermal conductivity and thermoelectric coefficient are determined by the electrical conductivity alone. At small frequency, in the hydrodynamic limit, we are able to provide a number of analytic formulas for the electrical conductivity. A dominant feature of the conductivity is the presence of a cyclotron pole. We show how bulk electromagnetic duality acts on the transport coefficients.
325 citations
TL;DR: A survey of solar-based driven thermoelectric technologies and their applications is presented in this paper, where a brief analysis of the environmental problems related to the use of conventional technologies and energy sources is presented and the benefits of using renewable energy systems are outlined.
Abstract: In this paper a survey of solar-based driven thermoelectric technologies and their applications is presented. Initially, a brief analysis of the environmental problems related to the use of conventional technologies and energy sources is presented and the benefits offered by thermoelectric technologies and renewable energy systems are outlined. The development history of solar-based thermoelectric technologies is introduced together with the discussion of the existing drawbacks of current systems. Typical applications of the solar-driven thermoelectric refrigeration and the solar-driven thermoelectric power generation are presented in order to show to the reader the extent of their applicability. The application areas described in this paper show that solar-driven thermoelectric technologies could be used in a wide variety of fields. They are attractive technologies that not only can serve the needs for refrigeration, air-conditioning applications and power generation, but also can meet demand for energy conservation and environment protection.
272 citations
TL;DR: It is predicted that the magnetization direction of a ferromagnet can be reversed by the spin-transfer torque accompanying spin-polarized thermoelectric heat currents.
Abstract: We predict that the magnetization direction of a ferromagnet can be reversed by the spin-transfer torque accompanying spin-polarized thermoelectric heat currents. We illustrate the concept by applying a finite-element theory of thermoelectric transport in disordered magnetoelectronic circuits and devices to metallic spin valves. When thermalization is not complete, a spin heat accumulation vector is found in the normal-metal spacer, i.e., a directional imbalance in the temperature of majority and minority spins.
249 citations
TL;DR: In this article, the authors predicted a giant thermoelectric coefficient in a nanostructure consisting of metallic electrodes periodically patterned over graphene, which was deposited on a silicon dioxide substrate.
Abstract: The paper predicts a giant thermoelectric coefficient in a nanostructure consisting of metallic electrodes periodically patterned over graphene, which is deposited on a silicon dioxide substrate. The Seebeck coefficient in this device attains 30mV∕K, this value being among the largest reported ever. The calculations are based on a transfer matrix approach that takes a particular form for graphene-based devices. The results are important for future nanogenerators with applications in the area of sensors, energy harvesting, and scavenging.
243 citations
TL;DR: In this article, it was shown that strongly correlated semiconductor FeSb2 exhibits a colossal Seebeck coefficient of ~−45000μWK−2 cm−1 at 10 K and the thermoelectric power factor PF=S2·ρ−1, where ρ is the electrical resistivity, reaches a record high value of ~2300μWk−2
Abstract: For more than a decade strongly correlated semiconductors and Kondo insulators have been considered as potential thermoelectric materials Such materials have large d- or f-character of the electronic band structure close to the Fermi level that theoretically leads to Seebeck coefficients (S) with large magnitudes In this work it is shown for the first time that the strongly correlated semiconductor FeSb2 exhibits a colossal Seebeck coefficient of ~−45000 μVK−1 at 10 K The thermoelectric power factor PF=S2·ρ−1, where ρ is the electrical resistivity, reaches a record high value of ~2300 μWK−2 cm−1 at 12 K and is 65 times larger than that of the state-of-the-art Bi2Te3-based thermoelectric materials However, due to a large lattice thermal conductivity the dimensionless thermoelectric figure of merit is only 0005 at 12 K Nonetheless, the potential of FeSb2 as a future solid-state thermoelectric cooling device at cryogenic temperatures is underlined
TL;DR: The thermoelectric properties of Sb-doped Mg2Si have been characterized by Hall effect measurements at 300 K and by measurements of electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) between 300 and 900 K as mentioned in this paper.
TL;DR: In this paper, the role of Te substitution in enhancing thermoelectric properties is discussed in relation to the bipolar diffusion mechanism, and the forbidden energy gap is estimated to be 0.047 eV from the temperature corresponding to the occurrence of intrinsic excitation, which is in good agreement with Singh's theoretical calculation (0.05 eV) [D. J. Singh and W. E. Pickett, Phys. Rev.
Abstract: CoSb3-xTex(x=0.05−0.3) skutterudite polycrystals with an average grain size of 160 nm were fabricated by mechanical alloying combined with spark plasma sintering. The variation of lattice parameter with Te content indicates that the solution limit of Te was x=0.15, above which the impurity phases of Te, CoTe2, and CoSb2 appeared, and the matrix cracked above 500 °C. All samples behaved as degenerate semiconductors. The forbidden energy gap was estimated to be 0.047 eV from the temperature corresponding to the occurrence of intrinsic excitation, which is in good agreement with Singh’s theoretical calculation (0.05 eV) [D. J. Singh and W. E. Pickett, Phys. Rev. B 50, 11235 (1994)]. The CoSb2.85Te0.15 sample had the highest power factor and the lowest thermal conductivity, resulting in the highest thermoelectric figure of merit, ZT=0.93 at 547 °C. The role of Te substitution in enhancing thermoelectric properties is discussed in relation to the bipolar diffusion mechanism.
TL;DR: In this article, Bismuth-telluride-based alloy thin-film thermoelectric generators are fabricated by a flash evaporation method and the output voltage and the maximum output power near room temperature are estimated as a function of the temperature difference between hot and cold junctions of the thin-filtered generators.
Abstract: Bismuth–telluride-based alloy thin film thermoelectric generators are fabricated by a flash evaporation method. We prepare Bi 0.4 Te 3.0 Sb 1.6 (p-type) and Bi 2.0 Te 2.7 Se 0.3 (n-type) powders for the fabrication of the flash evaporated thin films. The overall size of the thin film thermoelectric generators, which consist of seven pairs of legs connected by aluminum electrodes, is 20 mm by 15 mm. Each leg is 15 mm long, 1 mm wide and 1 μm thick. We measure the output voltage and estimate the maximum output power near room temperature as a function of the temperature difference between hot and cold junctions of the thin film thermoelectric generators. In order to improve the performance of the generators, a hydrogen annealing process is carried out at several temperatures from 25 °C to 250 °C. The highest output voltage of 83.3 mV and estimated output power of 0.21 μW are obtained from a hydrogen annealing temperature of T a = 250 °C and a temperature difference of Δ T = 30 K. The hydrogen annealing temperature of T a = 250 °C also results in the best electrical performance for both p-type thin film (Seebeck coefficient = 254.4 μV/K, resistivity = 4.1 mΩ cm, power factor = 15.9 μW/cm K 2 ) and n-type thin film (−179.3 μV/K, 1.5 mΩ cm, 21.5 μW/cm K 2 ).
TL;DR: In this article, the effect of stretching treatment on the thermoelectric properties of copolymers was examined and the results showed that the stretch treatment significantly increased the electrical conductivity of the copolymer with the highest Seebeck coefficient.
TL;DR: In this article, the authors showed that low-dimensional reduction can increase boundary scattering of phonons and reduce lattice thermal conductivity, possibly without negatively affecting the electrical conductivity or Seebeck coefficient.
Abstract: Thermoelectricity is the phenomenon of conversion between thermal and electrical energy. Compared with other technologies, thermoelectric (TE) devices offer distinct advantages: they have no moving parts, contain no chlorofluorocarbons, and have a long lifetime of reliable operation. However, current TE materials have found limited commercial application due to their low efficiency. TE efficiency is related to a material-dependent coefficient, Z, and is often expressed as the dimensionless figure-of-merit, ZT, given by ZT= rS 2 T/j, where Tis the absolute temperature, r is the electrical conductivity, S is the Seebeck coefficient, and j is the total thermal conductivity. It becomes difficult to improve ZT beyond a certain point since the material properties S, r, and j are inter-dependent. [1] Presently, simple bulk materials have reached an upper limit of ZTat approximately 1. Hicks and Dresselhaus proposed that conversion of bulk materials to low dimensional materials might significantly enhance TE performance through phonon scattering and electron confinement effects. [2] Dimensional reduction has since been shown to increase boundary scattering of phonons and reduce lattice thermal conductivity, [3] possibly without negatively affecting the electrical conductivity or Seebeck coefficient. The positive effects of low-dimensionality on ZT have already been demonstrated through several theoretical [2,4–6] and experimental [7] investigations, a few of which were based on lead chalcogenide systems. [8,9] Harman et al. achieved an especially high ZTof 2.0 at 300 K with PbSeTe/PbTe quantum dot superlattices. [10] Bulk
TL;DR: In this article, a two-dimensional electron gas (2DEG) in SrTiO3 was used for thermoelectric energy conversion and achieved a Seebeck coefficient of 2.4.
TL;DR: In this paper, a layered microstructure of PbTe and Sb2Te3 in which the interlamellar spacing can be controlled by the temperature and time of the decomposition process is presented.
Abstract: Utilizing the decomposition of metastable Pb2Sb6Te11 into PbTe and Sb2Te3, we produced a layered (lamellar) microstructure of PbTe and Sb2Te3 in which the interlamellar spacing can be controlled by the temperature and time of the decomposition process. Adjacent PbTe and Sb2Te3 lamellae are crystallographically oriented, indicating high-quality epitaxy-like interfaces. Average lamellar spacings as small as 180 nm are observed, corresponding to a PbTe layer thickness of 40 nm. These nanoscale multilayers, formed by bulk processing, resemble thin-film superlattice thermoelectric materials, which have shown exceptionally high thermoelectric efficiency.
TL;DR: It is shown that combined Seebeck coefficient and electrical conductivity measurements provide an effective approach to probing the Fermi Level, carrier concentration and mobility in nanowires.
Abstract: The Seebeck coefficient, electrical conductivity, and thermal conductivity of individual chromium disilicide nanowires were characterized using a suspended microdevice and correlated with the crystal structure and growth direction obtained by transmission electron microscopy on the same nanowires. The obtained thermoelectric figure of merit of the nanowires was comparable to the bulk values. We show that combined Seebeck coefficient and electrical conductivity measurements provide an effective approach to probing the Fermi Level, carrier concentration and mobility in nanowires.
TL;DR: In this article, dense lead telluride (PbTe) nanocomposites were prepared from PbTe nanocrystals synthesized employing an aqueous solution-phase reaction.
Abstract: Dense lead telluride (PbTe) nanocomposites were prepared from PbTe nanocrystals synthesized employing an aqueous solution-phase reaction. This approach reproducibly synthesizes 100–150nm nanocrystals with a high yield of over 2g per batch. Densification using spark plasma sintering dimensionally integrated nanoscale grains within a bulk matrix, resulting in a uniform dispersion of nonconglomerated nanocrystals. Transport properties of PbTe nanocomposites were evaluated through temperature dependent resistivity, Hall, Seebeck coefficient, and thermal conductivity measurements. These nanocomposites show an enhancement in the thermoelectric properties compared to bulk polycrystalline PbTe with similar carrier concentrations. Our results also indicate a strong sensitivity to stoichiometry, surface oxygen adsorption, and porosity.
TL;DR: In this paper, the existence of a large thermoelectric figure of merit in (AgSbTe2)15(GeTe)85 has been known for many years.
Abstract: The existence of a large thermoelectric figure of merit in (AgSbTe2)15(GeTe)85 has been known for many years. However, the nature of the crystallographic transformation in these materials from a high-temperature cubic to a low-temperature rhombohedral polymorph and its effect on electrical transport has not been clearly established. Transmission electron microscopy studies were performed that show extensive twinning in the low-temperature structure, resulting from lattice strain during the dilation along the (111) crystallographic direction. Analysis of differential scanning calorimetric studies indicates that the transformation is of second order, so that the high-temperature cubic phase is nonquenchable. High-temperature x-ray diffraction was performed to establish the transformation temperature, which was found to be complete upon heating at a temperature of 510K. Results of electrical conductivity measurements as a function of temperature on as-cast samples are discussed in terms of the observed twinning.
TL;DR: A through-substrate hole under the suspended microdevice allows for transmission electron microscopy characterization of the nanofilm sample assembled on the device, which enables one to correlate the measured thermoelectric properties with the crystal structures of thenanofilms.
Abstract: Measuring in-plane thermoelectric properties of submicron thin films has remained a challenging task. Here we report a method based on a suspended microdevice for four-probe measurements of the Seebeck coefficient, thermal conductivity, electrical conductivity, and thermoelectric figure of merit of patterned indium arsenide (InAs) nanofilms assembled on the microdevice. The contact thermal resistance and intrinsic thermal resistance of the 40nm thick InAs nanofilm sample were measured by using the nanofilm itself as a differential thermocouple to determine the temperature drops at the contacts. The microdevice was also used to measure a 190nm thick silicon dioxide (SiO2) film and the results were compared with those reported in the literature. A through-substrate hole under the suspended microdevice allows for transmission electron microscopy characterization of the nanofilm sample assembled on the device. This capability enables one to correlate the measured thermoelectric properties with the crystal str...
TL;DR: In this article, the electrical conductivity, thermoelectric power, and metal-insulator−semiconductor diode properties of polyaniline prepared in ionic liquid (PANI) have been investigated.
Abstract: The electrical conductivity, thermoelectric power, and metal−insulator−semiconductor diode properties of polyaniline prepared in ionic liquid (PANI) have been investigated. The electrical conductivity of the polyaniline increases exponentially with increasing temperature. The electrical conductivity value at 28 °C is 0.21 S/cm. The Seebeck coefficient of the PANI decreases with increasing temperature. The electrical conductivity and thermoelectric power results suggest that the PANI is a p-type semiconductor polymer. The Al/PANI Schottky diode was fabricated and is a metal−insulator−semiconductor type device. The ideality factor n and barrier height φb values of the diode at 298 K were found to be 2.78 and 0.85 eV, respectively. The barrier inhomogeneities are a very important explanation of the higher values of the ideality factor. The Gaussian distribution function was suggested for describing barrier height inhomogeneities. The standard deviation of the barrier height distribution σo indicates the pres...
TL;DR: The best combination of Seebeck coefficient and conductivity was around 10-7 W m-1 K-2 with copolymers comprising thiophene units alternating with carbazole or indolocarbazole as mentioned in this paper.
Abstract: In a quest for thermoelectric polymeric materials novel polycarbazole and polyindolocarbazole derivatives were synthesized. Alkyl side chains on the carbazole cycle and different side chains (alkyl or benzoyl) on the nitrogen atom of the backbone unit were introduced. Optical, electrochemical, electrical, and thermoelectric properties were investigated on these polymers and on two poly(diindolocarbazole)s. Band structure calculations were used to predict which polymers might be promising as thermoelectric materials. The best combination of Seebeck coefficient and conductivity (power factor) was around 10-7 W m-1 K-2 with copolymers comprising thiophene units alternating with carbazole or indolocarbazole. This family of polymers possesses good Seebeck coefficients, but there is still a need to improve the electrical conductivity, to produce useful thermoelectric materials.
TL;DR: In this paper, the effect of Hf alloying on Ti site, Pt and Pd alloys on Ni site, and Sb doping on Sn site for the optimization of thermoelectric properties of TiNiSn-based compounds was investigated.
TL;DR: In this paper, a half-Heusler material with randomly distributed TiO2 particles has been synthesized by arc melting and annealing, and the temperature range of ∼300-850 K was measured.
Abstract: TiFexCo1−xSb half-Heusler materials with randomly distributed TiO2 particles have been synthesized by arc melting and annealing. Thermoelectric properties were measured in the temperature range of ∼300–850 K. TiCoSb shows n-type conduction, while TiFexCo1−xSb transfers to p-type conduction when x≥0.01. The electrical conductivity of p-type TiFexCo1−xSb increased with increasing Fe content. The maximum Seebeck coefficient reached about 300 μV/K at 850 K for x=0.15. Since Fe powder contained a trace of Fe2O3, a small amount of TiO2 particles formed during the synthesis process. The lattice thermal conductivity dramatically decreased with increasing Fe content, which was mostly caused by the introduction of in situ formed TiO2 particles, as well as the effects of mass fluctuation and strain field fluctuation due to the substitution of Fe to the Co site. The dimensionless figure of merit (ZT=S2σT/κ) was significantly improved over the whole temperature region, and a maximum ZT value of 0.45 has been obtained ...
TL;DR: In this article, the thermoelectric properties of nanostructured skutterudite CoSb3 have been investigated and shown to have n-type conduction and thermal conductivities are reduced compared with that of the sample prepared by the melt-annealing∕hot pressing method.
Abstract: Thermoelectric properties of nanostructured skutterudite CoSb3 have been reported. Nanosized CoSb3 powders were synthesized through a solvothermal route. The bulk materials with average grain sizes of 250 and 150nm were prepared by hot pressing and spark plasma sintering from the solvothermally synthesized CoSb3 powders. Both the samples show n-type conduction and the thermal conductivities are reduced compared with that of the sample prepared by the melt-annealing∕hot pressing method. A thermoelectric figure of merit of 0.61 has been obtained for the unfilled CoSb3 skutterudite by spark plasma sintering, which indicates that nanostructuring is an effective way to improve the thermoelectric properties of skutterudite compounds.
TL;DR: In this article, the effects of Si substitution on the temperature-dependent electrical resistivity, Seebeck coefficient, as well as thermal conductivity in the Heusler-type compound was investigated.
Abstract: We report the effects of Si substitution on the temperature-dependent electrical resistivity, Seebeck coefficient, as well as thermal conductivity in the Heusler-type compound ${\mathrm{Fe}}_{2}\mathrm{VAl}$ It is found that the substitution of Si onto the Al sites causes a significant decrease in the electrical resistivity and lattice thermal conductivity A theoretical analysis indicated that the reduction of lattice thermal conductivity arises mainly from point-defect scattering of the phonons With slight substitution, the Seebeck coefficient changes sign from positive to negative, accompanied by the appearance of a broad minimum at high temperatures These features are associated with the change in the electronic band structure, where the Fermi level shifts upwards from the center of the pseudogap due to electron-doping effect For $xg01$ in ${\mathrm{Fe}}_{2}{\mathrm{VAl}}_{1\ensuremath{-}x}{\mathrm{Si}}_{x}$, no broad minimum in the Seebeck coefficient appears, indicative of a dramatic modification in the band structure of these materials While the thermoelectric performance improves with increasing Si concentration, the largest figure-of-merit $ZT$ value among these alloys is still an order of magnitude lower than conventional thermoelectric materials
TL;DR: In this article, the variations in thermoelectric (TE) efficiencies ae of lead chalcogenide compounds (p-PbTe, n-PbbTe, p-pb0.55Te0.45, ppb1−xSnxTe1−y, pPbSe, and p-PbinS) at room temperature for the pressure P range of P∼0-10GPa are reported.
Abstract: The variations in thermoelectric (TE) efficiencies ae of lead chalcogenide compounds (p-PbTe, n-PbTe, p-Pb0.55Te0.45, p-Pb1−xSnxTe1−y, p-PbSe, and p-PbS) at room temperature for the pressure P range of P∼0–10GPa are reported. A colossal (∼100 times) pressure-tuned improvement of ae is found for PbTe-based crystals under application of P∼2–3GPa. The employed high-pressure cell with synthetic diamond anvils is a model of a simple and effective TE device.
TL;DR: In this paper, Bismuth sulfide thin films have been assembled by cross-linkage nanorods on surface-functionalized Si substrate with self-assembled monolayers.
Abstract: Bismuth sulfide thin films have been assembled by cross-linkage nanorods on surface-functionalized Si substrate with self-assembled monolayers. Results of transmission electron microscopy and electron diffraction revealed that highly crystalline Bi2S3 nanorods grow along c-axis direction. Electrical transport properties including resistivity (0.02Ωcm), thermopower (−755μVK−1), and carrier mobilities (1100cm2V−1s−1) of the Bi2S3 films at 300K are found superior to those of previously reported Bi2S3 samples. The Bi2S3 films exhibit a maximum thermoelectric power factor (3.97×10−3Wm−1K−2) at 450K. The enhancement of thermoelectric properties mainly originates from highly crystalline and oriented nanostructures embedded in the Bi2S3 films.