Papers by Keyword: Thermoelectric

Abstract: I report a first-principles investigation of nickel-doped magnetite as a candidate for thermoelectric applications. Substituting Ni at the octahedral Fe sites preserves the inverse spinel framework while introducing Ni 3d impurity levels near the Fermi energy. Using Boltzmann transport theory in the constant-relaxation-time approximation, I calculate temperature and carrier-concentration-dependent transport properties, namely, electrical conductivity, the Seebeck coefficient, the power factor, and electronic thermal conductivity for both n-type and p-type doping. I find that conductivity increases significantly with increasing doping level, while the Seebeck coefficient shows large peaks and even changes sign at moderate carrier densities. Notably, I observed a very large power factor that exceeds that of the commonly used thermoelectric materials at higher temperatures. However, the accompanying rise in electronic thermal conductivity highlights the need for phonon engineering to limit total heat transport. These results demonstrate that Ni substitution provides an effective route to tune the electronic structure and optimize the thermoelectric performance of magnetite under realistic operating conditions.

Abstract: Machine Learning (ML) approach seeks to open new frontiers in the search for novel thermoelectric materials that convert heat waste into useful electrical energy. Five regression-type ML algorithms Linear Regression, Random Forest, XGBoost, Bagging Regressor, and Gradient Boosting Regressor were employed in this study to forecast the thermoelectric figure of merit (ZT) of doped chalcogenide compounds. Gradient Boosting Regressor achieved the best baseline performance (R² = 94.5%, MAE = 0.073, RMSE = 0.128), further improved with hyperparameter tuning to R² = 95.8%, MAE = 0.065, and RMSE = 0.112. Compared to the baseline, tuning reduced RMSE by 12.6% and MAE by 10.8%. The optimized model reliably reproduced experimental ZT trends in doped Bi₂Te₂Se and Ag₂Te, validating its predictive capacity. Our findings show that hyperparameter tuning is greatly recommended for high-fidelity predictions in thermoelectrics.

Abstract: Tin Selenide, Lead Selenide, and Lead Telluride are known best thermoelectric materials for mid and high-temperature electric generation applications. The bilayer of these materials could enhance the quality of a thermoelectric generation. The present work deals with bilayer deposition of SnSe/PbTe and SnSe/PbSe in glass substrates using physical vapor deposition followed by annealing at 323K, 423K, and 523K. The structure and morphology of the films have been investigated by XRD, SEM, and FESEM studies. The thermoelectric pursuance of both bilayer thin films was studied with the temperature as a function in the range of 300K to 623K. Both films exhibit the maximum Seebeck coefficient. The electrical Conductivity and Power factor increased gradually for SnSe/PbTe thin films and SnSe/PbSe thin films for the samples annealed up to 573K and then decreases. The electronic thermal conductivity of both films was very low compared to the total thermal conductivity. The absolute thermal conductivity at room temperature was calculated by Transient Hot Wire (THW) method. The maximum Figure of Merit (ZT) value obtained for SnSe/PbTe and SnSe/PbSe at room temperature was 0.81 and 1.3 for 573K annealed thin films respectively.

Abstract: Thermoelectric-based on Thermoelectric Generator (TEG) is a method of converting heat energy into electrical energy directly if there is a temperature difference (∆T) between the hot side temperature (Th) and the cold side temperature (Tc) of the TEG. Compared to conventional energy conversions such as steam turbines, this thermoelectric technology has no moving parts, is compact, quiet, highly reliable, environmentally friendly, and operated for long periods with minimal maintenance. This study aims to develop TEG technology as a means of converting heat energy from geothermal sources, especially those with medium and low temperatures (< 180 °C). The method used in this research is to conduct experiments to obtain the ideal TEG characteristics for use in medium and low temperature geothermal conditions. To achieve this goal, a characteristic test was conducted for five types of TEG with criteria including a maximum operating temperature of 200 °C. The parameters that measured in this experiment are temperature T, voltage V, current I and electric power P. Based on data, the results is TEG1-241-1.4-1.2 is the most optimal power that produce output power 6.5 Watt at 150 °C.

Abstract: Heat transfer simulation in Bi₂Te₃, Ca₂FeMoO₆, and SrTiO₃ solid module single-leg had been investigated using COMSOL Multiphysics package. The software COMSOL Multiphysics was used to investigate the temperature distribution, electrical potential distribution, power output, and current vs temperature throughout the length of the sample for Bi₂Te₃, Ca₂FeMoO₆, and SrTiO₃ which one of these three materials was showing potential as TE materials. The simulation showed that the perovskite material Ca₂FeMoO₆ and SrTiO₃ had shown a net temperature difference across lengths of +191.943°C and +7.54°C while Bi₂Te₃ showed a net temperature difference of -60°C. Next, in electrical potential distribution across the length, Ca₂FeMoO₆ and SrTiO₃ produced a higher voltage of 170mV and 160mV, while Bi₂Te₃ produced 49mV. The values of the power output for the three materials were calculated with 0.7A input current. It was found that Ca₂FeMoO₆, SrTiO₃, and Bi₂Te₃ generated 119mW, 113mW, and 34mW in the simulation. The simulation results revealed that the Bi₂Te₃ is a p-type thermoelectric element and has the potential use in cooling due to Peltier cooling effect. However, Ca₂FeMoO₆ and SrTiO₃ are n-type thermoelectric elements with a heating effect. The simulation and investigation of TE material using COMSOL Multiphysics showed more potentials and helped to explore, predicted and evaluated the conditions for other new TE materials.

Abstract: Controlling the polymerization of polypyrrole (Ppy) in presence of Zr-based metal organic-framework (Zr-MOFs) using sodium dodecyl sulphonate (SDS) as a dopant, leads to the formation of a new class of thermoelectric materials based on conducting polymer and highly porous MOFs with enhanced properties for energy production applications. The polymerization of polypyrrole in the Zr-Fumerate pores leads to the formation of homogenously coated MOF-spheres with high crystalinity and a high degree of improvement in many electrical properties such as conductivity and carrier mobility. The figure shows the movement of the electrons from the hot to the cold side in the aligned polymer inside the MOF pores.

Abstract: In this study, SnO₂ nanoparticles of wt% 2, 4, 6, and 8 were uniformly composite in Bi₂Te₃ matrix. SnO₂ nanoparticle was synthesized using co-precipitation method. The result shows that based on XRD and EDS analysis the composites do not contain any impurities. The thermoelectric properties of the composites strongly depend on the Seebeck coefficient. The highest value of Seebeck coefficient of -177 µV/K is obtained at around 375 K for the 4% SnO₂/Bi₂Te₃ sample. This yields the highest value of the power factor of 4.0 × 10^-3 Wm^-1K^-1 compared to the pure Bi₂Te₃ synthesized using the same procedure by 14.3%. This result demonstrates that the thermoelectric properties of Bi₂Te₃ can be improved using oxide nanoparticles.

Abstract: In this work, we use first principles DFT calculations, anharmonic phonon scatter theory and Boltzmann transport method, to predict a comprehensive study on the thermoelectric properties as electronic and phonon transport of layered LaSe₂ crystal. The flat-and-dispersive type band structure of LaSe₂ crystal offers a high power factor. In the other hand, low lattice thermal conductivity is revealed in LaSe₂ semiconductor, combined with its high power factor, the LaSe₂ crystal is considered a promising thermoelectric material. It is demonstrated that p-type LaSe₂ could be optimized to exhibit outstanding thermoelectric performance with a maximum ZT value of 1.41 at 1100K. Explored by density functional theory calculations, the high ZT value is due to its high Seebeck coefficient S, high electrical conductivity, and low lattice thermal conductivity .

Abstract: The electronic structure and thermoelectric properties of CaMnO₃ doped with 8% and 17% f block element Sm using first principles calculations and semi-classic Boltzmann theory were presented in this paper. The G-type AFM phase is most stable among five phases for CaMnO₃, however, with 8% and 17% Sm doping, these compounds became nonmagnetic phases. CaMnO₃ calculated electronic band structure shows an indirect band gap of 0.523 eV, which is underestimated by the density functional theory (DFT) calculations but the band gap explains the semiconducting behavior. However, with 8% and 17% Sm doping, the electronic bandstructure of these compounds exhibit metallic behavior, with Sm and Mn 3d electrons contributing to conduction band, increasing the magnitude of conductivity for doped compounds. All temperature dependence Seebeck coefficient plots show n-typed conduction for all compound with reduced magnitude of Seebeck coefficient for doped compounds. The temperature dependence thermal conductivity plot shows overall thermal conductivity is reduced in Sm doped compound. CaMnO₃ with 17% Sm doping exhibit much higher ZT of 0.32 at 800 K showing enhanced thermoelectric properties at high temperature and suitability or high temperature energy conversion devices.

Abstract: The effects of Al doping to the thermoelectric properties of ZnO thin films fabricated through ink-jet printing were studied in this paper. Ink-jet printing was used to deposit the Al doped ZnO thin films. A minimum of 50 print cycles was required to obtain continuous film with approximately 9 μm thick thin films. It was possible to obtain high thermoelectric properties of ZnO by controlling the ratios of dopant added and the temperature of the heat treatments.The XRD traces of Al doped ZnO exhibit a polycrystalline hexagonal structure for the wurtzite phase of ZnO. There were no additional phase detected for Al doped ZnO thin films with increasing amount of Al dopants and heat treatment temperature. The results show Al doping had improved the thermoelectric properties of ZnO with an increased in electrical conductivity. The electrical conductivity of pure ZnO thin film (5 S/cm) was enhanced with increasing the dopant to 4wt% Al doped ZnO (114 S/cm). Negative Seebeck values were observed for all the samples that indicated n-type semiconductor. Pure ZnO samples have a measured Seebeck coefficient-17.63 μV/K decreased to-14.35 μV/K with 4 wt% Al doped.