Thermoelectric Characteristics Research Articles

Effect of functional on structural, elastic stability, optoelectronic and thermoelectric characteristics of semiconducting MgX2Se4 (X = Lu, Y) spinels

Effect of functional on structural, elastic stability, optoelectronic and thermoelectric characteristics of semiconducting MgX2Se4 (X = Lu, Y) spinels

Tuning the mechanical and thermoelectric properties of self‐standing stretchable PEDOT:PSS/SDBS films

AbstractPoly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has recently attracted significant attention as a potential candidate for small‐scale thermoelectric conversion because of its ease of doping, and solution processability. This study addressed the fabrication of self‐standing PEDOT:PSS films modified with sodium dodecylbenzene sulfonate (SDBS) surfactant, presuming different annealing temperatures. According to the investigation, optimizing the annealing temperature improves crystal quality and increases the efficiency of PEDOT:PSS films. The resulting PEDOT:PSS films showed the highest electrical conductivity of about 623.68 Scm−1 and maximum power factor of 25.87 μWm−1 K−2. In addition to confirming thermoelectric properties; SDBS surfactants are being investigated to plasticize PEDOT:PSS films at different concentrations and annealing temperatures. With an optimization in annealing temperature, the elongation at break value similarly improves; and the highest elongation at break was observed at 0.94 wt% SDBS concentration, reaching 32%. To completely understand the underlying reasons for this dependence, higher‐order structures and electronic states of polymer films have been examined using electronic reflectance spectroscopy and X‐ray diffraction analysis. Overall, the outcomes of this work show how important surfactants and their annealing temperature are for improving the mechanical and thermoelectric characteristics of self‐standing PEDOT:PSS films.

Optoelectronic and transport properties of Lead-Free halide based Na2AgTlZ6 (Z = Cl, Br, I) double perovskites for energy harvesting applications

The bandgap engineering and deliberate band edge manipulation of perovskites make them potential candidates for the photovoltaic industry. Here we theoretically investigate the structure, density of states, and photovoltaic and thermoelectric characteristics of Na2AgTlZ6 (Z = Cl, Br, I) using WIEN2k code. The incorporation of Br and I at the Cl site caused the increase in lattice constant which leads to the decrease in bulk modulus and Debye temperature. The computed values of Poisson (<0.26) and Pugh (<1.75) ratio verified their brittle nature. The bandgap analysis reveals direct bandgap nature and bandgap value lie in the visible region for parent composition and infrared and far infrared when Cl is replaced with Br and I. The density of state plots uncovers the shifting of energy states in valence and conduction bands towards the Fermi level with the increasing number of electrons in the halogens. The increase in the value of dielectric constant, refractive index, and shifting of peaks towards lower energy value is witnessed with atomic number of halogen atoms. The viability of these compositions for thermoelectric devices is further confirmed when electrical conductivity and Seebeck coefficient dependent Figure of merit and power factor are evaluated in the temperature range of 200–800 K. In addition, the anisotropic nature of studied compositions is explored through the computation of the modulus of elasticity including Young’s modulus, Shear modulus in addition to compressibility, and Poisson’s ratio.

First-principles screening of optoelectronics and thermoelectric response of XAcTe2 (X=K, Rb) full Heusler alloys: mBJ+SOC effect

Structural geometry, Electronic, optical, and thermoelectric attributes of XAcTe2 (X=K,Rb) full Heuser alloys were investigated theoretically via density functional theory (DFT). Structural optimization yielded optimized lattice parameters along with obtained negative formation energies (Ef) revealed the thermodynamically stable cubic geometries of alloys under investigation. For both alloys, the computed electronic band dispersions exhibit semiconductor behavior with a direct band gap. The band gap value of KAcTe2 is 1.59 eV, and 1.66 eV for RbAcTe2. The analysis of optical response shows maximum absorption α (ω) in the ultraviolet (UV) region, validating their quality for photovoltaic devices. The investigation of thermoelectric characteristics showed that both alloys display higher electrical conductivities and lower thermal conductivities.

Large Transverse Thermoelectric Power Factor in Topological Semimetal NbAs2

AbstractThe distinctive properties of topological semimetals, including linear band dispersion and compensated electron‐hole carriers, have positioned these materials at the forefront of research in power generation and solid‐state cooling due to their remarkable magneto‐thermoelectric performance. In this work, the transverse thermoelectric characteristics of the topological semimetal NbAs2 are studied. Specifically, under a magnetic field of 9 T, the Nernst coefficient displays a linear and unsaturated trend, reaching a peak of 600 µV K−1 at 35 K. Consequently, this engenders a substantial transverse power factor (tPF) of 850 µW cm−1 K−2 under a 5 T magnetic field. The exceptional attributes of NbAs2 driven by its remarkably high carrier mobility and compensated electron‐hole concentration near the Fermi level are revealed by band structure analysis based on theoretical calculations and quantum oscillations. This work not only underscores the immense potential of topological semimetals as transverse thermoelectric materials for niche applications where magnetic fields exist but also provides valuable guidance for the discovery and optimization of topological materials for promising thermoelectric performance.

Pressure influenced electronic phase transition, mechanical, optoelectronic, and transport characteristics of double perovskite Rb2AgSbCl6: A first-principles investigation

In this work, we used density functional theory (DFT) simulations to investigate the structural, elastic, electronic, optical, and transport characteristics of pressure-induced Rb2AgSbCl6. By calculating the octahedral and the tolerance factors, the phase stability has been verified. The calculated formation energy and Gibbs free energy values have demonstrated the thermodynamic stability of the material. The outcomes of the mechanical behavior analysis revealed that the pressure-driven Rb2AgSbCl6 is mechanically stable and sustains ductility as well as anisotropy. Additionally, as the pressure is increased from 0 GPa to 100 GPa, the band gap has been reduced from 2.64 eV to 0 eV. The hydrostatic pressure of 100 GPa was the critical pressure at which the material revealed a metallic nature. The optical properties such as absorbance and optical conductivity shift towards lower energy and comparatively higher at increased pressure with minimal energy loss. The thermoelectric characteristics are examined utilizing the BoltzTraP code at different pressures. The figure of merit (ZT) value was increased from 0.76 to 0.80 with the increase in pressure at room temperature. These characteristics render pressure-influenced Rb2AgSbCl6 favorable candidates for utilization in solar cells as well as thermoelectric devices.

Probing the electronic structure, optical, and transport nature of lanthanide-based ternary materials: A First-principles perspective

High thermal stability and adjustable optoelectronic properties are the unique characteristics of lanthanide-based materials. The complex interplay between unique electronic, optical, and thermoelectric characteristics of lanthanide-based ternary chalcogenides is investigated by first principles modeling. The cohesive energy values were anticipated to be −4.54 eV/atom for PrSF and −4.87 eV/atom for PrSBr suggesting PrSBr to have the greatest bonding properties and is the most stable material. The computed formation energies range from −1.3 to −3.0 (eV/f. u), demonstrating their stability. The inclusion of bromine, a more electronegative element than fluorine, produces unique hybridization patterns and spin polarization effects. Compared to PrSBr, PrSF bonding employs more effective orbital hybridization, resulting in a greater band gap. PrSF has a higher frequency dielectric constant compared to PrSBr. The absorption edges in the ε2(ω) result from optical transitions between the Pr-f, S-p, F-p, and Br-p states. As the temperature rises, the Seeback coefficients for PrSF and PrSBr decrease exponentially. The thermal conductivity spectra of PrSF and PrSBr materials exhibit a linear increase across the temperature range. As temperature rises, the concentration of carriers and mobility increases, resulting in increased electrical conductivity values.

Transport properties of mechanochemically synthesized copper (I) selenide for potential applications in energy conversion and storage

This work studied the thermal stability, electrical, and thermoelectrical properties of copper(I) selenide, Cu2Se synthesized by high-energy milling in a planetary ball mill. The phase composition was investigated by X-ray powder diffraction analysis and scanning electron microscopy. The conversion of the precursors during mechanochemical synthesis and the stability of the product was monitored by thermal analysis. The dependence of electrical properties on the product porosity was observed. For the densification of Cu2Se, the method of spark plasma sintering was applied to prepare suitable samples for thermoelectric characterization. High-temperature thermoelectric properties of synthetic Cu2Se were compared to its natural analogue-mineral berzelianite in terms of its potential application in energy conversion. Based on the results a relatively high figure-of-merit, ZT parameter (~ 1.15, T = 770 K) was obtained for undoped Cu2Se, prepared by rapid mechanochemical reaction (5 min). Cyclic voltammetry measurements of Na/NaClO4/Cu2Se cell implied that mechanochemically synthesized Cu2Se could be used as a promising intercalation electrode for sodium-ion batteries.

Interlayer coupling modulated for thermoelectric transport characterization of black arsenic nanoscale devices

Modulating interlayer coupling modes can effectively enhance the thermoelectric properties of nanomaterials or nanoscale devices. By using density functional theory combined with non-equilibrium Green’s function method, we investigate the thermoelectric properties of zigzag-type black arsenic nanoscale devices with varying interlayer coupling modes. Our results show that altering the interlayer coupling mode significantly modulates the thermoelectric properties of the system. Specifically, we consider four coupling modes with different strengths, by modulating different interlayer overlap patterns. Notably, in the weaker interlayer coupling mode, the system exhibits enhanced thermoelectric properties due to increased interface phonon scattering, for example, the M4 reaching a peak value of 2.23 at μ = −0.73 eV. Furthermore, we explore the temperature-dependent behavior of each coupling model. The results suggest that the thermoelectric characteristics are more sensitive to temperature variations in the weaker coupling modes. These insights provide valuable guidance for enhancing the thermoelectric performance of nanoscale devices through precise interlayer coupling modulation.

Experimental study on thermoelectric characteristics of intermediate fluid thermoelectric generator

Thermoelectric technology plays a crucial role in harnessing waste heat from automobile exhaust, and developing low-resistance and high-efficiency thermoelectric generator is currently a focal point of research. The intermediate fluid thermoelectric generator (IFTEG) introduces a structural modification to conventional designs by utilizing boiling-condensation heat transfer of the intermediate fluid to enhance power generation performance. In this study, we constructed an experimental system to investigate the thermoelectric characteristics of IFTEG. The results demonstrate that the IFTEG outperforms traditional thermoelectric generators, exhibiting a remarkable increase in total output power ranging from 171% to 283%, a reduction in pressure drop ranging from 23% to 42%, and a significant improvement in voltage distribution uniformity across the modules. Increasing the exhaust temperature and flow rate significantly enhances the net output power while minimally affecting the voltage distribution uniformity. The net output power of 10.17 W and the net thermoelectric conversion efficiency of 1.39% are achieved at 200 °C and 30 m3/h. Overall, this novel generator offers advantages such as low pressure loss, high efficiency, and high reliability. The findings of this study provide valuable guidance for the development of exhaust thermoelectric generators.

Study of mechanical, thermodynamic, thermoelectric, and optical properties of Cs2SbAuX6 (X = Cl, Br, I) for energy harvesting applications

The inorganic double perovskites (DPs) Cs2SbAuX6 (X = Cl, Br, I) are an emerging applicant for solar cells, optoelectronic, and thermoelectrics to acquire clean energy. Therefore, the present research thoroughly addresses the mechanical, thermodynamic, optical, and thermoelectric characteristics by modified Becke and Johnson potential of Trans and Balaha (TB-mBJ) and BoltzTraP code. The structural stability is narrated from the tolerance factor and thermodynamic stability by formation energy. Born criteria assure the mechanical existence of cubic structures. The Cs2SbAu(Cl/Br)6 is ductile, and Cs2SbAuI6 has brittle behavior with a metallic nature. The band structures analysis reports the narrow band gaps for Cl/Br and the zero band gap for I-based DPs. The optical properties are studied by dielectric constants, absorption bands, refractive index, and other dependent optical parameters. Lastly, thermoelectric characteristics regarding Seebeck coefficient, electrical conductivity, power factor, thermal conductivity, and figure of merit in the temperature range 200–600K are analyzed. ZT's significant value at room temperature makes them potential candidates for thermoelectric generators.

DFT study of optoelectronics and transport properties of double perovskites Cs2YCuX6 (X = Cl, Br, I) for energy conversion devices

Double perovskite halides (DPHs) hold great promise for applications in energy conversion. This article provides a comprehensive exploration of the elastic, thermoelectric and optoelectronic characteristics of Cs2YCuX6 (X = Cl, Br, I) DPHs. The elastic constants and phonon dispersion curves reveal ductile nature and mechanical and thermodynamic stability of the examined materials. The Born stability criteria ensures structural stability, while the formation energy ranging from −2.28 to −1.68 eV signifies thermodynamic viability. Furthermore, the thermodynamic stability of investigated double perovskites Cu2YCuX6 (X = Cl, Br, I) have been verified by performing ab-initio finite temperature molecular dynamics (MD) simulation. The examination of mechanical characteristics affirms the ductile nature of the material, and its substantial anisotropic factor enhance its significance for device fabrication. The band gaps calculated at 2.65 eV, 2.55 eV, and 2.45 eV from band structures, highlight the significance of the studied double perovskites (DPs) for optoelectronic applications. Optical parameters yield information on minimal dispersion and expansive absorption band. Additionally, transport characteristics are analyzed through parameters such as Seebeck coefficient, thermal conductivity, electrical conductivity, and the Figure of merit (ZT).

Physical properties of CoX'ZrGa (X' = V, Cr) quaternary-Heuslers: A first-principles investigation

The prime intention of this investigation is to examine the magnetic, thermoelectric, mechanical, electrical, structural, and thermodynamic characteristics of CoVZrGa and CoCrZrGa quaternary Heusler compounds. The FP-LAPW approach and Boltzmann transport equation are employed, utilizing classical Boltzmann approximations in the background of density functional theory (DFT) as implemented within WIEN2K software. The structure optimization employed the PBE approximations and the Murnaghan-Birch equation of state, leading to a stable phase for CoVZrGa and CoCrZrGa. The observed negative formation energy implies that the synthesis of CoVZrGa and CoCrZrGa is feasible. The Heusler compounds under investigation, which exhibit a narrow band gap in one spin direction and metallic behavior in the other, are classified as half-metallic (HM) based on the analysis of their electronic properties. The results for thermodynamic and elastic parameters confirm both alloys' thermal and mechanical stability. Critical analysis of thermoelectric properties demonstrates these compounds ssare feasible materials for thermoelectrical applications.

A pressure tunable optical and thermoelectric properties of Rb2CuSbX6 (X = cl, Br, and I) by FPLAPW+lo method

The pressure dependencies of the structural, electrical, elastic, optical, and thermoelectric characteristics of the Halide double perovskites (HDPs) Rb2CuSbX6 (X = Cl, Br, and I) compounds were computed using the FP-LAPW method within the density functional theory framework, under high pressure conditions. HDPs received a lot of attention due to their potential application in optoelectronic and thermoelectric devices. The Perdew-Burke-Ernzerhof (PBEsol-GGA) is used to investigate the structural properties of selected compounds, while the modified Becke-Johnson (mBJ) functional is used to obtain a better agreement between the calculated optoelectronic and electronic properties and experimental observations. The Born criteria and formation energy are explored for the stability of all selected HDPs. The elastic constants of cubic symmetry are investigated to determine the difference between ductile and brittle nature, anisotropy, and bulk modulus. The bandgaps for Rb2CuSbCl6, Rb2CuSbBr6, and Rb2CuSbI6 are 1.08 eV, 0.72 eV, and 0.33 eV, respectively. Decrease band gap with increase in pressure. The density of states plots under zero pressure exhibit a combination of ionic and covalent bonding, whereas an increase in pressure results in a reinforcement of covalent bonding. The absorption spectra are observed in the infrared region. All HDPs were further analyzed with respect to optical absorption, refractive index, and dielectric constants for the energy range 0–10 eV. Additionally, Boltzmann classical theory explains the lower lattice temperature, greater Seebeck coefficient, thermal conductivity, and electrical conductivity of HDPs, making them for thermoelectric applications.

On the Structural, Magnetic, Electronic, Optical, and Thermoelectric Characteristics of the Solar Perovskite CsCdI3: DFT and SCAPS-1D Studies

On the Structural, Magnetic, Electronic, Optical, and Thermoelectric Characteristics of the Solar Perovskite CsCdI3: DFT and SCAPS-1D Studies

Enhanced Heat Transfer in Thermoelectric Generator Heat Exchanger for Sustainable Cold Chain Logistics: Entropy and Exergy Analysis

This study investigates the application of thermoelectric power generation devices in conjunction with cold chain logistics transport vehicles, focusing on their efficiency and performance. Our experimental results highlight the impact of thermoelectric module characteristics, such as thermal conductivity and the filling thickness of copper foam, on the energy utilization efficiency of the system. The specific experimental setup involved a simulated logistics cold chain transport vehicle exhaust waste heat recovery thermoelectric power generation system, consisting of a high-temperature exhaust heat exchanger channel and two side cooling water tanks. Thermoelectric modules (TEMs) were installed between the heat exchanger and the water tanks to use the temperature difference and convert heat energy into electrical energy. The analysis demonstrates that using high-performance thermoelectric modules with a lower thermal conductivity results in better utilization of the temperature difference for power generation. Additionally, the insertion of porous metal copper foam within the heat exchanger channel enhances convective heat transfer, leading to an improved performance. Furthermore, the study examines the concepts of exergy and entropy generation, providing insights into the system energy conversion processes and efficiency. Overall, this research offers valuable insights for optimizing the design and operation of thermoelectric generators in cold chain logistics transport vehicles to enhance energy utilization and sustainability.

DFT study of mechanical, optoelectronic, and thermoelectric characteristics of double perovskites Li2CuTiZ6 (Z = Cl, Br, I) for energy harvesting technology

Recent studies have produced stable inorganic perovskites that contain no lead, replacing lead-containing perovskites' risky and unstable properties. The present investigation thoroughly examined the electrical behavior, elastic characteristics, optical features, and transport properties of Li2CuTlZ6 (Z = Cl, Br, I) halides in order to discover potential applications. The Wien2k code was utilized to apply density functional theory (DFT) in order to clarify these physical properties. Using the generalized gradient approximation (PBEsol-GGA), we determined structural parameters through the energy optimization procedure that corresponded with the available data. Additionally, elastic parameters as well as formation energies ranging between -2.33 to -1.39 eV were used to validate cubic durability for the two halides. Moreover, the modified Becke-Johnson (mBJ) potential successfully provided precise direct bandgap values for all halides. According to this study, the shift in anions from Cl to Br is responsible for the reduction in band gap within the infrared spectrum. Our computed optical parameter findings show that Li2CuTlCl6 and Li2CuTlBr6 halides demonstrate excellent optoelectronic efficiency with low reflection, strong optical absorption, and conductivity. The investigation clarifies that the temperature-dependent character of the materials electrical transport properties is due to their very small bandgap. These materials may find use in thermoelectric applications, as evidenced by the almost unity of the obtained figure of merit, which points to their semiconducting behaviour.

First-principle investigation of lead-free double perovskites Cs2MScCl6 (M = Na, K) for optoelectronic and thermoelectric applications

Double perovskite optoelectronic devices are gaining popularity due to their advantageous features, such as an efficient and easy-to-manage crystalline structure. In this study, we looked into the optoelectronic, mechanical, and thermoelectric attributes of Cs2MScCl6 (with M being Na or K) using density functional theory. The obtained results show that both compounds can exist stably in cubic double perovskite structure, space group Fm3¯m . The electronic band structures of Cs2NaScCl6 and Cs2KScCl6 demonstrate a direct semiconducting band gap of 3.829 eV and 3.996 eV, respectively. As the pressure rises up to 200 GPa, Cs2KScCl6 reveals extraordinary tunability along with an indirect band gap of 2.000 eV. Moreover, optical analysis—comprising dielectric constant calculations, absorption coefficient measurements, refractive indices checks, reflectivity assessments, energy loss estimations, and electrical conductivity appraisals—shows promising results too. Specifically, the absorption coefficient and conductivity predominantly fall within the ultraviolet range under normal atmospheric pressure. The thermoelectric characteristics suggest a noteworthy Seebeck coefficient, low thermal conductance and good figure of merit implying it could be used in the domain of sustainable energy.

Ab initio analysis of structural, optoelectronic, thermoelectric, and elastic characteristics of K2MBiBr6 (M = Na, Ag, and Cu) for green energy

Ab initio analysis of structural, optoelectronic, thermoelectric, and elastic characteristics of K2MBiBr6 (M = Na, Ag, and Cu) for green energy

Optoelectronic and thermoelectric properties of Cs2PtX6 (X=Cl, Br, I) for energy conversion applications: DFT calculations

This research employs density functional theory within the WIEN2k framework to simulate Cs2PtX6 (X = Cl, Br, I) perovskites. The study focuses on assessing the structural stability and thermodynamic properties through the computation of tolerance factor and formation energies, affirming the viability of the simulated materials. Notably, this investigation reveals a direct bandgap semiconducting character of these compounds, with specific values of the bandgap of 2.9, 2.15, and 1.08 eV for Cl, Br, and I-based compositions, respectively. The analysis of optical behavior demonstrates a redshift in absorption edge and an increase in optical conductivity, correlating with the enlarging halogen size within the series. The investigation into the thermoelectric characteristics of Cs2PtX6 perovskites, which include σ and κe as well as S, PF, and ZT, underscores the potential of Cs2PtX6 perovskites for deployment in thermal energy harvesting devices. Furthermore, the mechanical behavior assessment indicates the ductile nature of studied compounds, contributing to their overall mechanical stability. This study gives a comprehensive recognition of structural, electronic, mechanical, optical, and transport characteristics of Cs2PtX6 compounds, suggesting their promise for applications in advanced materials for optoelectronic and thermoelectric devices.