Seebeck Coefficient Measurements Research Articles

Effect of Thickness Variation on the Measured Seebeck Coefficient and Power Factor in ITO–NiCr Thin‐Film Thermocouples

Herein, the electrical resistivity, Seebeck coefficient, and power factor of an indium tin oxide (ITO) and nickel‐chromium (NiCr) thermocouple are investigated. The thicknesses of the ITO and NiCr are varied between 10 and 430 nm. Seebeck coefficients between 12.8 and (21.4 ± 1.5) μV K−1 are measured, respectively. The results indicate that a reduction in thickness generally leads to an increase in the Seebeck coefficient until a maximum value is reached. Among the measured samples, the optimal Seebeck coefficients are found with an ITO thickness of (111 ± 4) nm and NiCr thickness of (18 ± 2) nm. Finally, the power factor of the thermocouples is determined, with a maximum power factor of (84 ± 7) μW m−1 K−2 for the ITO thickness of (111 ± 4) nm and nickel‐chromium thickness of (42 ± 5) nm.

Magnetic and transport properties in metallic and disordered Ru2VAl and Ru2VGa

In this work, we report an elaborate study on the structural, magnetic and thermoelectric properties of two Ru-based Heusler alloys, viz., Ru2VAl and Ru2VGa, having valence electron count 24. While Ru2VGa exhibits a nonmagnetic ground state, in Ru2VAl a short range ferromagnetic interaction is developed below 10 K due to the structural antisite defects and disorder, that also manifests its signature in the specific heat and electrical resistivity measurements at low temperatures. Both the Seebeck coefficient (S) and Hall measurements suggest the dominance of hole-type carrier for electronic transport in Ru2VAl whereas Ru2VGa is found to be a n-type material. The linear nature and small absolute values of S, as well as non-zero values of electronic contribution to specific heat γS (γSRu2VAl = 4.9 mJ/mol-K2 and γSRu2VGa = 5.5 mJ/mol-K2) point towards a metallic ground state for both these alloys. Both the compounds exhibit lower thermal conductivity at room temperature in comparison to Fe-based Heusler alloys due to the presence of heavier element Ru.

Surface Chemistry and Band Engineering in AgSbSe2: Toward High Thermoelectric Performance.

AgSbSe2 is a promising thermoelectric (TE) p-type material for applications in the middle-temperature range. AgSbSe2 is characterized by relatively low thermal conductivities and high Seebeck coefficients, but its main limitation is moderate electrical conductivity. Herein, we detail an efficient and scalable hot-injection synthesis route to produce AgSbSe2 nanocrystals (NCs). To increase the carrier concentration and improve the electrical conductivity, these NCs are doped with Sn2+ on Sb3+ sites. Upon processing, the Sn2+ chemical state is conserved using a reducing NaBH4 solution to displace the organic ligand and anneal the material under a forming gas flow. The TE properties of the dense materials obtained from the consolidation of the NCs using a hot pressing are then characterized. The presence of Sn2+ ions replacing Sb3+ significantly increases the charge carrier concentration and, consequently, the electrical conductivity. Opportunely, the measured Seebeck coefficient varied within a small range upon Sn doping. The excellent performance obtained when Sn2+ ions are prevented from oxidation is rationalized by modeling the system. Calculated band structures disclosed that Sn doping induces convergence of the AgSbSe2 valence bands, accounting for an enhanced electronic effective mass. The dramatically enhanced carrier transport leads to a maximized power factor for AgSb0.98Sn0.02Se2 of 0.63 mW m-1 K-2 at 640 K. Thermally, phonon scattering is significantly enhanced in the NC-based materials, yielding an ultralow thermal conductivity of 0.3 W mK-1 at 666 K. Overall, a record-high figure of merit (zT) is obtained at 666 K for AgSb0.98Sn0.02Se2 at zT = 1.37, well above the values obtained for undoped AgSbSe2, at zT = 0.58 and state-of-art Pb- and Te-free materials, which makes AgSb0.98Sn0.02Se2 an excellent p-type candidate for medium-temperature TE applications.

Physical properties of the full Heusler-type Ru2-Fe NbAl (x = 0.00–0.50) alloys

We report the physical properties of a series of full Heusler-type Ru2-xFexNbAl (x = 0.00–0.50) alloys using magnetization, electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) measurements. Structure and phase analysis via x-ray diffraction and scanning electron microscopy indicate that Fe replaces the Ru in Ru2NbAl, and the antisite disorders reduce. The dc magnetization shows predominantly paramagnetic behavior for all Fe-doped samples, as in the pristine Ru2NbAl sample. Interestingly, the electrical resistivity measurements reveal that the conduction behavior of Ru2NbAl alloy changes from semiconducting-like to metal-like with Fe substitution. In addition, a minimum in resistivity at low temperatures is observed in the Fe-doped samples. It is noted that the minimum shifts to low temperatures with Fe content, presumably due to the weak localization effect. The Seebeck coefficient measurements show that charge carriers of these alloys remain hole type with a maximum S value of ∼27 µV/K at 300 K for x = 0.13, a result of the modification of the electronic band structure. The Fe substitution is found to reduce thermal conductivity significantly. An analysis of the lattice thermal conductivity indicates that the reduction in κ is primarily due to more grain boundaries, Umklapp phonons, and electron scatterings. These observations lead to an increase in the thermoelectric performance, i.e., the figure of merit and power factor, to about 0.007 and 1.7 μW/cm K2 at 300 K for the optimized composition of Fe with x = 0.13.

Impacts of Annealing Temperature and Time on the Thermoelectric Performance of Recycled Carbon Fiber (RCF)/n-Bi2Te3 Heterostructure Thermoelectric Composites

Recycling carbon fibre waste is crucial for sustainability in the composites industry. Herein, we report the fabrication of a heterostructure composite using recycled carbon fiber (RCF) and n-type bismuth telluride (n-Bi2Te3) for thermoelectric applications. In the present study, we have comprehensively investigated the effects of annealing temperature and time on the thermoelectric, structural, charge carrier transport, morphological, and thermal stability properties of annealed RCF/n-Bi2Te3 composites. The optimum annealing temperature and time were at 350 °C and 2 h, respectively, which yielded a maximum power factor of 7.83 μWK−2m−1. Annealing redistributed the bismuth and tellurium atomic percentage, decreased carrier concentration, improved carrier mobility, enhanced the crystallinity and increased the grain size of the bismuth telluride particles, subsequently improving the thermoelectric performance as well as the thermal stability of annealed RCF/n-Bi2Te3 composites. In addition, this study has explored the plausibility of a cross-plane configured Seebeck coefficient measurement utilizing recycled carbon fibre/n-type bismuth telluride heterostructure thermoelectric composite. Energy band diagram analysis indicated favorable heterojunction alignment between RCF and n-Bi2Te3, validating the viability of the thermoelectric composite in a cross-plane configuration. Our study provides a promising route for closing the recycling loop of carbon fiber waste and achieving sustainable thermoelectric materials.

Improving the Performance of Layer-by-Layer Processed Organic Solar Cells via Introducing a Wide-Bandgap Dopant into the Upper Acceptor Layer.

The layer-by-layer (LbL) solution-processed organic solar cells (OSCs) are conductive to achieve vertical phase separation, tunable donor-acceptor (D/A) interfaces, and favorable charge-transport pathways. In this work, a wide-bandgap component poly(9-vinylcarbazole) (PVK) is added to the upper electron acceptor layer to improve the performance of LbL-processed OSCs. Results show that the PVK component can adjust the film morphology, dope the electron acceptor, increase the electron concentration, and improve charge transport. Such n-type doping is verified by Seebeck coefficient measurement, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance characterization. In addition, the fluorescence intensity and exciton lifetime of the PVK-doped acceptor film are increased, thus being beneficial for exciton diffusion to the D/A interface. Therefore, the power conversion efficiency (PCE) of LbL OSCs increases when 2.50 wt.% PVK is employed in the electron acceptor layer of commonly-used high-efficiency system and a maximum value of 19.05% can be achieved. The role of PVK played in the active layer is different from those of additives and ternary components reported previously, so the results provide an alternative way to enhance the device performance of LbL-processed OSCs.

The role of hetero-interface structures in enhancing the power factor of Cu2Se/x% Y2O3 composite thermoelectric materials

In this study, we have investigated the structural, thermal, electrical, and mechanical properties of the composite system Cu2Se/x% Y2O3 (0 ≤ x ≤ 1.00) as a function of varying Y2O3 concentration, x. The successful incorporation of Y2O3 in the Cu2Se matrix is carried out using the solid-state reaction method, and the same is confirmed by X-ray diffraction analysis. Due to the low concentration of Y2O3, all the prepared composites exhibit monoclinic crystal structure with P2/m space group within the X-ray detection limit at room temperature. The oxidation state of the studied composites is investigated using X-ray photoelectron spectroscopy (XPS). The composites exhibit an increase in mechanical hardness as a function of Y2O3 concentration, whereas the electrical resistivity shows no systematic variation with Y2O3 concentration. The highest resistivity is observed for the sample with x = 1%. The measured Seebeck coefficient (S) value increases with increasing temperature. The positive values of S indicate that the positive charge carriers (holes) dominate the thermoelectric transport. The thermal conductivity of the composites increases as compared to the Cu2Se pristine sample. The overall power factor and ZT of studied composites were found to decrease with the addition of Y2O3 to the Cu2Se system.

Experimental evidence of a size-dependent sign change of the Seebeck coefficient of Bi nanowire arrays

The electrical transport in bismuth nanowires is strongly influenced by both sample geometry and crystallinity. Compared to bulk bismuth, the electrical transport in nanowires is dominated by size effects and influenced by surface states, which gain increasing relevance with increasing surface-to-volume ratios, i.e. with decreasing wire diameter. Bismuth nanowires with tailored diameter and crystallinity constitute, therefore, excellent model systems, allowing to study the interplay of the different transport phenomena. Here, we present temperature-dependent Seebeck coefficient and relative electrical resistance measurements of parallel bismuth nanowire arrays with diameters between 40 and 400 nm synthesized by pulsed electroplating in polymer templates. Both electrical resistance and Seebeck coefficient exhibit a non-monotonic temperature dependence, with the sign of the Seebeck coefficient changing from negative to positive with decreasing temperature. The observed behavior is size-dependent and is attributed to limitations of the mean free path of the charge carriers within the nanowires. The observed size-dependent Seebeck coefficient and in particular the size-dependent sign change opens a promising avenue for single-material thermocouples with p- and n-legs made from nanowires with different diameters.

Influence of indium and selenium co-doping on structural and thermoelectric properties of Bi2Te3 alloys

The melt-grown, indium and selenium co-doped Bi2Te3 single-crystal system is studied with a purpose to improve and analyze the thermoelectric performance in the low and near room-temperature range (10–400 K). The influence of co-dopants on the crystalline perfection, symmetry, dislocation, and single-crystal quality is investigated using high-resolution X-ray diffraction. The surface morphological features show the existence of small-angle grain boundaries, white patches, and tilt boundaries. Degenerate type of semiconducting behavior is seen in all the samples over the entire temperature range. The existence of small polarons is experimentally inferred from temperature-dependent electrical resistivity. Measurement of Seebeck coefficient confirms p- to n-type transition in the crystals doped with indium and selenium. The total thermal conductivity at 11 K was decreased by 3.4 times in (Bi0.98In0.02)2Te2.7Se0.3 as compared to pristine sample. Therefore, this novel co-doped indium and selenium Bi2Te3 single-crystal combination is viable to use as a competitor for low and near-room-temperature thermoelectric applications.

Nanostructured Thermoelectric PbTe Thin Films with Ag Addition Deposited by Femtosecond Pulsed Laser Ablation

Pulsed laser deposition operated by an ultra-short laser beam was used to grow in a vacuum and at room temperature natively nanostructured thin films of lead telluride (PbTe) for thermoelectric applications. Different percentages of silver (Ag), from 0.5 to 20% of nominal concentration, were added to PbTe deposited on polished technical alumina substrates using a multi-target system. The surface morphology and chemical composition were analyzed by Scanning Electron Microscope and X-ray Photoelectron Spectroscopy, whereas the structural characteristics were investigated by X-ray Diffraction. Electrical resistivity as a function of the sample temperature was measured by the four-point probe method by highlighting a typical semiconducting behavior, apart from the sample with the maximum Ag concentration acting as a degenerate semiconductor, whereas the Seebeck coefficient measurements indicate n-type doping for all the samples. The power factor values (up to 14.9 µW cm−1 K−2 at 540 K for the nominal 10% Ag concentration sample) are competitive for low-power applications on flexible substrates, also presuming the achievement of a large reduction in the thermal conductivity thanks to the native nanostructuring.

In situ electrical and thermal transport properties of FeySe1−xTex films with ionic liquid gating

We combine in-situ electrical transport and Seebeck coefficient measurements with the ionic liquid gating technique to investigate superconductivity and the normal state of FeySe1-xTex (FST) films. We find that the pristine FST films feature a non-Fermi liquid temperature dependence of the Seebeck coefficient, i.e., S/T ~ AS lnT, and AS is strongly correlated with the superconducting transition temperature (Tc). Ionic liquid gating significantly raises Tc of FST films, for which the Seebeck coefficient displays a novel scaling behavior and retains the logarithmic temperature dependence. Moreover, a quantitative relationship between the slope of T-linear resistivity (A\r{ho}) and Tc for gated films is observed, i.e., (A\r{ho})1/2 ~ Tc, consistent with previous reports on cuprates and FeSe. The scaling behaviors of AS and A\r{ho} point to a spin-fluctuation-associated transport mechanism in gated FeySe1-xTex superconductors.

Sb-doped Tl8.67 Sn1.33-xSbx Te6 nanoparticles improve power factor and electronic charge transport

Thallium telluride Tl8.67 Sn1.33-xSbxTe6 nano compound doped with different concentration ratios of Sb (x = 0.63, 0.65, 0.66, 0.68, 0.70, or 0.72) was prepared using solid-state techniques, and the compound was heated up to 550 K in vacuum silica tubes. The structure of the nano system was studied using XRD and EDX. It was confirmed that, without any other impurities, the nano system had a single-phase tetragonal crystal structure. The measured Seebeck coefficient (S) of all nano compounds showed that S increased with increase in temperature from 300 to 550 K. S was positive at all temperatures, showing characteristics of a p-type semiconductor. The complex behaviour of S in an Sb-doped nano system showed that at low temperature (room temperature), S first decreased with an increase in Sb concentration up to x = 0.65 and then increased with an increase in the Sb dopant up to x = 0.72. Similarly, electrical conductivity (σ) decreased with an increase in temperature, and the power factor showed complex behaviour relative to Sb concentration. The power factor observed for Tl8.67 Sn1.33-xSbx Te6 nano compound increased with an increase in temperature, within a temperature range of 300–550 K. Tellurides are semiconductors of very narrow band-gap, with component elements in common oxidation states, according to (Tl+9) (Sb3+) (Te2-)6. The phase range was also assessed, and results demonstrated that different Sb dopant ratios were associated with differences in properties (e.g., electrical, thermal, and Seebeck effect) and hence variation in power factor. These results indicate a route through which the thermoelectric characteristics of Tl8.67 Sn1.33-xSbxTe6-based nano materials were harnessed for the development of thermoelectric and electronic applications.

Synthesis and Characterization of Multinary Selenides A4B10Se19 (A=Sn, Pb; B=Sb, Bi)

AbstractMultinary selenides A4B10Se19 (A=Sn/Pb; B=Sb/Bi), including Sn4Bi10Se19, Pb4Sb6.71Bi3.29Se19, and Pb4Sb3.43Bi6.57Se19, were prepared by solid‐state reactions. These compounds adopt the Felbertalite structure type that crystallizes in the monoclinic space group C2/m (No. 12). Single‐crystal and powder X‐ray diffraction measurements studied the crystal structure and site preference of metal sites. They exhibit stacking of stepped layers (NaCl111‐type) and ribbon‐shape (NaCl100‐type) units that are connected via shared Se2− ions. Electronic structure calculations indicated semiconducting properties and were verified by temperature‐dependent conductivity and Seebeck coefficient measurements. The thermoelectric properties show a maximum power factor of 1.06 μW ⋅ m−1 ⋅ K−2 at 550 K for Pb4Sb6Bi4Se19.

Study of parallel models for thermoelectric properties of double-layer thermoelectric thin films

Currently, the measurement and prediction of the electrical transport performance of thermoelectric double-layer membrane is often based on the theory of parallel model. However, the conditions under which the parallel model can be used lack theoretical and experimental support and validation. In this work, the Seebeck coefficients of Cu/Si and Ag/Si bilayers under applied temperature difference are obtained by using finite element theory simulations with the help of COMSOL Multiphysics software and compared with the results from the parallel model. Whether the ends of the bilayer plated with a metal Pt layer, and the insertion of a high-resistance/low-resistance/insulation interface between the bilayers affect the Seebeck coefficient measurements of the bilayer are investigated. It is found that when there is no Pt at the hot end or cold end, the potentials on the Si side and Cu side at the high-resistance and electrically insulating interfaces are uniformly distributed along the direction of the temperature gradient, respectively, and the measured Seebeck coefficients are the same as the values of the materials’ own, respectively, and the thermal potential on the Cu side at the low-resistance interface varies uniformly with the probe spacing <i>L</i>, while the thermal potential on the Si side shows a non-uniform variation. With Pt, the thermal potentials on the Cu side and Si side are uniformly distributed along the direction of the temperature gradient, and the measured values on both Si side and Cu side are the same as the Cu Seebeck coefficients, regardless of the insulating/high-resistance/low-resistance interface. The Si/Ag and Bi/Ag bilayers are investigated experimentally. In the absence of Pt, the absolute value of the Seebeck coefficient on the Si side of Si/Ag bilayer decreases with temperature decreasing, but the absolute value of the Seebeck coefficient on the Ag side increases with temperature decreasing. In the presence of Pt, the Seebeck coefficients on both sides of the Bi/Ag bilayer membrane are equal.

Structure, electrical and thermal properties of single-crystal BaCuGdTe3.

Single crystals of the quaternary chalcogenide BaCuGdTe3 were obtained by direct reaction of elements allowing for a complete investigation of the intrinsic electrical and thermal properties of this previously uninvestigated material. The structure was investigated by high-resolution single-crystal synchrotron X-ray diffraction, revealing an orthorhombic crystal structure with the space group Cmcm. Although recently identified as a semiconductor suitable for thermoelectric applications from theoretical analyses, our electrical resistivity and Seebeck coefficient measurements show metallic conduction, the latter revealing strong phonon-drag. Temperature dependent hole mobility reveals dominant acoustic phonon scattering. Heat capacity data reveal a Debye temperature of 183 K and a very high density of states at the Fermi level, the latter confirming the metallic nature of this composition. Thermal conductivity is relatively high with Umklapp processes dominating thermal transport above the Debye temperature. The findings in this work lay the foundation for a more detailed understanding of the physical properties of this and similar multinary chalcogenide materials, and is part of the continuing effort in investigating quaternary chalcogenide materials and their suitability for use in technological applications.

Annealing effect on the thermoelectric properties of multiwall carbon nanotubes

In this article, it is demonstrated that transport properties and thus thermoelectric performance of multiwall carbon nanotubes (MWCNTs) can be enhanced significantly by annealing. Two different samples of MWCNTs with small and large diameters were investigated. The as-prepared MWCNT samples were treated at different conditions of annealing. The pristine and annealed MWCNTs were investigated using x-ray diffraction, Raman spectroscopy and scanning electron microscope in order to investigate the microstructure, defect content and morphology before and after the annealing process. The electrical conductivity, Seebeck coefficient and thermal conductivity were measured over the temperature range of (300–450 K) and were found to correlate with the tube diameter and the annealing conditions. The electrical conductivity and Seebeck coefficient measurements show that the conduction mechanism in MWCNTs is thermal activation as the samples have degenerate semiconductor-like behavior. Upon annealing, the Seebeck coefficient increases, followed by a reduction in the thermal conductivity. The thermoelectric power factor was enhanced by annealing to realize the highest value of 1.06 μW m −1 K −2 at 475 K for the sample with the larger diameter. The thermoelectric figure of merit ZT was calculated to determine the performance of the materials. ZT of the sample of the larger tube's diameter was enhanced by about 247% at 450 K. • Pristine and annealed MWCNTs were investigated using x-ray diffraction, Raman spectroscopy and scanning electron microscope. • Thermoelectric performance of multiwall carbon nanotubes (MWNTs) is significantly enhanced by annealing. • The thermoelectric figure of merit ZT was enhanced by about 247% at 450 K.

Qualification of Fe0.95Co0.05Si2 as a reference material for high temperature measurement of the thermoelectric power factor

Precise characterization of thermoelectric (TE) materials is mandatory for a meaningful validation of scientific results, focusing on traceable determination of the Seebeck coefficient (S), the electric (σ) and thermal (κ) conductivity. These properties form the thermoelectric figure of merit zT = (S2σ/κ)T, which is used for assessment of TE conversion efficiency with respect to the absolute temperature T. The level of metrological standardization is characterized to date by available reference samples for the Seebeck coefficient, publications on best practice measurement approaches, and accomplished international round robin (RR) campaigns on transport property measurements.We report on the qualification of β-Fe0.95Co0.05Si2 (FeSi2) as the first semiconducting high temperature reference material for the TE power factor (PF = S2σ), which is currently developed by the German Aerospace Center (DLR) and the Physikalisch-Technische Bundesanstalt (PTB). The relation between the size of FeSi2 compacts obtained by current-assisted short time sintering and the resulting functional homogeneity of the material is presented, which is studied by spatially resolved Seebeck coefficient measurements at room temperature. Data from temperature dependent characterization of the PF is provided to assess functional stability and homogeneity under integral measurement conditions. The outcome of certification measurements at PTB report on individual uncertainty contributions as the base for a later testimony of FeSi2 as a metrological reference for the PF. Integral measurements have been expanded to further comparative test results obtained by the Korea Electrotechnology Research Institute (KERI), the Indian Institute of Technology Bombay (IITB), and the Netzsch Gerätebau GmbH. The findings give evidence of an excellent homogeneity, reproducibility and stability with low standard deviations for S and σ far below typical measurement uncertainties, which effectively demonstrates the suitability of FeSi2 as a future reference material for TE metrology at elevated temperatures up to 1000 K.

Effect of Annealing on the Microstructure, Opto-Electronic and Hydrogen Sensing Properties of V2O5 Thin Films Deposited by Magnetron Sputtering

This paper reports results of investigations on selected properties of vanadium oxide thin films deposited using gas impulse magnetron sputtering and annealed at temperatures in the range of 423 K to 673 K. Post-process annealing was shown to allow phase transition of as-deposited films from amorphous to nanocrystalline V2O5 with crystallite sizes in the range of 23 to 27 nm. Simultaneously, annealing resulted in an increase in surface roughness and grain size. Moreover, a decrease in transparency was observed in the visible wavelength range of approximately 50% to 30%, while the resistivity of formed vanadium pentoxide thin films was almost unchanged and was in the order of 102 Ω·cm. Simultaneously, the best optoelectronic performance, testified by evaluated figure of merit parameter, indicated the as-deposited amorphous films. Performed Seebeck coefficient measurements indicated the electron type of electrical conduction of each prepared thin film. Furthermore, gas sensing properties towards diluted hydrogen were investigated for annealed V2O5 thin films, and it was found that the highest senor response was obtained for a thin film annealed at 673 K and measured at operating temperature of 623 K.

Phase-transition-induced thermal hysteresis in Type-II weyl semimetals [formula omitted] and [formula omitted]

The resistivity versus temperature measurement is commonly used for identifying temperature-induced phase change and the resulting hysteresis loop. While the resistance is influenced by both the density of states and the carrier lifetimes, the Seebeck coefficient is influenced predominantly by the density of states, and hence is a better probe of the phase of the material. Here, 1T′−Td temperature-induced phase transition in MoTe2 is studied using temperature-dependent X-ray diffraction, resistivity, and Seebeck coefficient measurements. A more distinct hysteresis is observed when measuring the Seebeck coefficient which is consistent with direct measurements of the crystallographic angle using the temperature-dependent X-ray diffraction. The Seebeck and electrical resistivity measurements indicate a competing contribution of the electrons and holes. The contribution of electron pockets becomes more dominant when molybdenum atoms are replaced by tungsten. In MoTe2, a topologically induced enhancement of the Nernst coefficient is observed at low temperatures, and a relatively large phase-transition induced Thomson coefficient of 111 μV⋅K−1 is measured at 254 K which is larger than the Seebeck coefficient measured in the entire temperature range.

Enhancing the thermoelectric power factor of nanostructured SnO2 via Bi substitution

Tin dioxide (SnO2) has recently proved to be a promising material for thermoelectric applications. We have investigated the influence of highly valence Bi doping as an electron donor in oxygenated SnO2 materials on their thermoelectric properties. We have synthesized the pure and Bi doped SnO2 nanoparticles (x = 0%, 5%, 10%, and 15%) through a simple hydrothermal approach. The Seebeck coefficient and Hall measurements have been used to determine thermoelectric behaviour. The measured value of the Seebeck coefficient increases from - 56 to - 83 μV/°C as the Bi content increases. This improvement in the Seebeck coefficient has been attributed to the charge carrier localization (energy filtering effect) caused by the inclusion of the bismuth atoms and the presence of secondary phases based on BiO2. However, the electrical conductivity measurements show an inverse relation with the Bi doping, increasing the impurities. The Sn1-xBixO2 sample with x = 15 has achieved the maximum Seebeck value, resulting in the upward trend in power factor of up to 1.97 × 10−4 Wm−1C−2. Further, we have used X-ray diffraction and scanning electron microscopy to determine the effect of Bi on the SnO2 crystal structure and surface morphology. Which also demonstrates the presence of composites with mixed phases.