Peak Power Factor Research Articles

Enhanced thermoelectric and mechanical performance of Bi2S3 bulk materials by compositing with Bi0.33(Bi6S9)Br nanorods

Recently, Bi2S3 has garnered significant interest in the thermoelectric field due to its abundant and low-toxicity constituents. Nevertheless, pure Bi2S3 material has not been utilized in thermoelectric applications because of its low electrical conductivity. This study presents the fabrication of the Bi0.33(Bi6S9)Br-doped Bi2S3 bulk samples with high electrical conductivity and mechanical performance via the melting method in conjunction with spark plasma sintering technology. The increased electron concentration is attributed to the replacement of S2− by Br− and the introduction of extra Bi in the lattice. At 323 K, the electrical conductivity of the Bi2S3 + 3 wt% Bi0.33(Bi6S9)Br sample increased to 208 Scm−1, signifying a 3-order-of-magnitude enhancement compared to the pure sample. The enhanced electrical conductivity led to the optimization of the electrical transport properties. At 573 K, the Bi2S3 + 2 wt% Bi0.33(Bi6S9)Br bulk sample achieved a peak power factor value of 481 μWm−1K−2, which is four times higher than that of the pure sample. Notably, the low lattice thermal conductivity of the Bi2S3 + 5 wt% Bi0.33(Bi6S9)Br sample was 0.56 W−1 m−1K−1 at 673 K. Given the significantly enhanced electrical transport properties and suppressed thermal conductivity, the Bi2S3 + 2 wt% Bi0.33(Bi6S9)Br sample achieved a peak ZT value of 0.45 at 673 K and a high ZTave value of 0.33 from 373 to 673 K. Compared to the pure Bi2S3 sample, these values are 5 times and 3 times higher, respectively. Such advancements can be implemented in the domain of power generation. Additionally, the mechanical properties of the sample exhibited substantial enhancement, and the average hardness of the 2 wt% Bi0.33(Bi6S9)Br-doped sample increased from 2.73 GPa of the pure sample to 3.03 GPa. This novel strategy of dual point defects modulation provides a new pathway to enhance the thermoelectric performance of Bi2S3 and other material systems.

Irradiation Effect in Thermoelectric Polymer Polyaniline Induced by High-Energy Electron Beam

A comprehensive investigation was conducted on the relationships between molecular structure, morphology and thermoelectric properties of HCl-doped polyaniline (PANi) nanorods subjected to 10[Formula: see text]MeV electron beam irradiation. Morphological and structural characterization revealed that the crystallinity of irradiated PANi nanorods remained almost unchanged, and minimal oxygen content was detected. This resulted in minimal alterations to the thermo-stability. In addition, the thermoelectric properties of PANi were enhanced. A maximum conductivity of 22.85[Formula: see text]S/cm was obtained at 50[Formula: see text]kGy, which was 1.46 times that of pristine PANi. Interestingly, the Seebeck coefficient reached a maximum of −3.56[Formula: see text][Formula: see text]V/K at 100[Formula: see text]kGy, indicating [Formula: see text]-type organic semiconductor properties. However, a peak power factor of 0.024[Formula: see text][Formula: see text]W[Formula: see text]m[Formula: see text] K[Formula: see text] was achieved with 60[Formula: see text]kGy irradiation, which was slightly enhanced compared to 0.018[Formula: see text][Formula: see text]W[Formula: see text]m[Formula: see text][Formula: see text]K[Formula: see text] for pristine PANi. These results demonstrate that PANi exhibits good irradiation resistance after irradiated with a dose of 100[Formula: see text]kGy. Thus, PANi could be used in high-[Formula: see text] ray (electron) environments, such as radioisotope thermoelectric generators (RTGs).

Enhancing the thermoelectric and mechanical properties of Cu3SbSe4-based materials by defect engineering and covalent bonds reinforcement

Here, a typical microwave hydrothermal-assisted synthesis method is utilized to fabricate Co/Sn co-doped Cu3SbSe4 materials. Experimental results demonstrate that the formation of a nanoscale Co9Se8 phase occurs when the solid solubility of Co is exceeded. This phase effectively enhances phonon scattering at the grain boundary's high-density dislocation region, leading to a significant reduction in lattice thermal conductivity. Simultaneously, the interface between Co9Se8 and Cu3SbSe4 exhibits an energy filtering effect, resulting in an improved Seebeck coefficient. The maximum zT value of 0.62 is achieved in the Cu3Sb0.96Co0.04Se4 sample. To further regulate the carrier concentration, Sn atoms are introduced, leading to peak power factor and zT values of 865.98 μW·m−1·K−2 and 0.72, respectively. The incorporation of Co and Sn doping contributes to the enhancement of mechanical properties by reinforcing covalent bonds. Mechanical property testing of the materials indicates an improvement in mechanical performance upon doping with Co and Sn. This study provides valuable insights into the in-situ introduction of a second phase through element doping, thereby enhancing the comprehensive thermoelectric properties of Cu3SbSe4-based materials. Moreover, it establishes an experimental foundation for subsequent investigations into the materials' mechanical properties.

Simultaneous realization of high power factor and low thermal conductivity in medium-entropy La-doped (Sr1/3Ba1/3Ca1/3)1-xLaxTiO3 oxides with porous structure

Some studies have proven the effectiveness of high-entropy alloying in reducing lattice thermal conductivity; however, the synchronous degradation in carrier mobility limits the thermoelectric properties of high-entropy materials. Herein, we present a series of medium-entropy oxides (Sr1/3Ba1/3Ca1/3)1-xLaxTiO3 (x = 0.05, 0.1, 0.15) with different levels of La doping, breaking the trade-off between carrier and phonon transport. The medium-entropy design helps keep the carrier mobility at a moderate level while modulating the carrier concentration through La3+ doping, thereby yielding a peak power factor value of 1842 μW/(m⋅K2) at 773 K. Meanwhile, the incorporation of nano-micro-porous structure and medium entropy effect leads to a significant reduction in lattice thermal conductivity, reaching 2.3 W/(m⋅K) at 1073 K. Consequently, a ZTmax value of 0.67 is obtained for the MEP-10La sample at 1073 K, which is one of the state-of-the-art ZT values reported for the SrTiO3-based materials. The present work provides a viable approach for the development of thermoelectric materials with enhanced performance.

New Recipe for Enhancing the Thermoelectric Performance in Topological Materials Carrying Single‐Pair Weyl Points Fermions and Phonons

AbstractThe emergence of various topological semimetal states presents a novel opportunity for enhancing the efficiency of thermoelectric transport. This study introduces a recipe to improve the thermoelectric (TE) performance in topological materials containing single‐pair Weyl points (SP WPs) fermions and phonons. The recipe focuses on two key factors contributing to the enhancement of TE performance: the increase in the density of states to achieve a high power factor, and the introduction of additional phonon scattering to reduce the lattice thermal conductivity. The proposed recipe is confirmed in a half‐metallic SP WPs material BaNiIO6 through first‐principles methods. An enhanced density of states arises near the energy of the SP WPs in BaNiIO6, leading to a peak power factor connected to the complex Fermi surface due to the degeneracy of Weyl pockets in energy. Furthermore, it is shown that the SP WPs phonons in BaNiIO6 possess a high scattering rate and can likely contribute to the low lattice thermal conductivity, especially when two crossing points in SP WPs do not degenerate in frequency. The new recipe can be used for discovering high‐performance thermoelectric materials in the future by utilizing the transport advantages of degenerate‐in‐energy SP WPs fermions and non‐degenerate‐in‐frequency SP WPs phonons.

Encapsulated Ag2Se-based flexible thermoelectric generator with remarkable performance

Flexible thermoelectric generators hold great potential for powering wearable electronics. Herein, we employ a novel encapsulation technology to fabricate a Ag2Se-based composite film, which possesses a remarkable room-temperature power factor (PF) of 25.6 μW cm−1 K−2 and a peak PF of ∼27 μW cm−1 K−2 at 380 K. The microscopic origin of the above performance is attributed to the appearance of CuAgSe second phase by our in-situ transmission electron microscopy evidences. Moreover, the encapsulation guarantees the Ag2Se layer in a zero-strain state, contributing to a negligible relative resistance change (<0.2%) even after 2000 bending cycles under a bending radius of 3 mm. The encapsulated flexible thermoelectric generator assembled with six Ag2Se legs demonstrates a maximum power density of 130 W m−2 at a temperature difference of 60 K and is compatible with harsh working environment.

Optimization of IEA-R1 reactor core parameters using the particle swarm algorithm

This work aims on the development of a FORTRAN 90 code to solve the Loading Pattern Optimization Problem (LPOP) in the IEA-R1 research reactor at the Nuclear and Energy Research Institute (IPEN/CNEN-SP) in São Paulo, Brazil. The code integrates the Particle Swarm Optimization (PSO) method, with the current reactor calculation methodology. The objective function seeks to maximize the effective multiplication factor (keff), minimize the peak power factor (PPF), and achieve the most uniform neutron flux distribution possible. A comparison with the parameters of the reactor’s current configuration, and the code successfully finds solutions meeting the standard problem requirements. The new configuration enhances peak power (6.93%) and variance (9.62%), slightly increases neutron flux (0.48%), and marginally reduces in keff (0.45%). Additionally, it lowers the maximum fuel cladding temperature (0.7%), contributing to reactor safety.

Neutronic analysis of the BYU molten salt micro reactor

Background: With the rising need for reliable and clean energy, researchers at Brigham Young University created a molten salt microreactor (MSMR) concept to help meet the world’s growing energy demands. The MSMR is rated at 45 MWth and is uniquely capable of passively dissipating all decay heat using conduction only. Methods: This work presents the results of the simulated neutronic behavior of the MSMR using the Monte Carlo neutronics code OpenMC with the ENDF/B-VII.1 cross-section library at steady state conditions. The specific characteristics discussed in this work are: keff, power profile, axial and radial peak power factors, Doppler coefficient of reactivity, and the moderator temperature feedback coefficient. Results: At steady state operating conditions, keff was calculated to be 1.07091 ± 0.00087 indicating that this configuration can achieve criticality. The axial peaking power factor was found to be 1.003 and the radial peaking power factor was found to be 1.45. Feedbacks were calculated by offsetting the temperature of the fuel and the moderator respectively. Doppler coefficient of reactivity to be -12.585 pcm/K and the moderator temperature coefficient of reactivity to be -0.34332 pcm/K. Conclusions: It is worth noting that the largest contributor of the negative reactivity comes from the fuel salt and not the moderator, further demonstrating the safety of the reactor. Future work will include a full neutronic optimization of the core, fuel burn up analysis, and exploration of a suitable burnable neutron poison.

Origins of three‐dimensional charge and two‐dimensional phonon transports in Pnma phase PbSnSe2 thermoelectric crystal

AbstractRecently, PbSnSe2 alloy was found to exhibit a large hysteresis effect on transport properties, demonstrating its significant potential for thermoelectric applications. Using ab initio approaches, we studied the carrier transport properties of PbSnSe2 crystal, which is a special case of the alloy with the shortest‐range order. A peak power factor of 134.2 μW cm−1 K−2 was found along the cross‐plane direction in the n‐type PbSnSe2 at a doping concentration of 7 × 1020 cm−3 at 700 K. This high power factor originates from delocalized p electrons between intra‐plane Pb–Se pairs and between cross‐plane Sn–Se pairs that can build up transport channels for conducting electrons, leading to a high electrical conductivity of 5.9 × 105 S m−1. Introducing Pb atoms into Pnma phase SnSe can decrease the phonon group velocities and enhance the phonon–phonon scatterings, leading to a low thermal conductivity of 0.53 W m−1 K−1 at 700 K along the cross‐plane direction. The calculated peak ZT of ~3 along the cross‐plane direction at an n‐type doping concentration of around 5 × 1019 cm−3, which represents a theoretical upper limit for an idealized PbSnSe2 crystal. This work interprets the origins of three‐dimensional charge and two‐dimensional phonon transport behavior in PbSnSe2 and demonstrates that such crystals are promising high‐performance thermoelectric semiconductors.

Scrap Recovery of n‐Type Bismuth Telluride Ingot by Second Zone Melting and PbBr2 Doping

Bismuth telluride is the only commercially applied thermoelectric material. The n‐type material is usually prepared by the method of zone melting; however, the utilization ratio of the ingot is relatively low, owing to the bad thermoelectric performance of the two ends. Herein, the waste of n‐type bismuth telluride is recovered by the second zone melting and PbBr2 doping. It is shown that the second zone melting can improve the grain alignment, leading to the increase of carrier mobility. When PbBr2 doping is introduced, lattice thermal conductivity is largely reduced by the high dense dislocations. As a result, the peak power factor and maximum ZT reach 53 μW cm−1 K−2 and 1.15, respectively, which are even higher than the values of the original commercial material. This work provides an economic and applicable strategy to recover the waste of bismuth telluride thermoelectric materials.

Modulation Doping Leads to Optimized Thermoelectric Properties in n‐Type Bi6Cu2Se4O6 due to Interface Effects

AbstractHeterogeneous composites consisting of Bi6Cu2Se3.6Cl0.4O6 and Bi2O2Se are prepared according to the concept of modulation doping. With prominently increased carrier mobility and almost unchanged effective mass, the electrical transport properties are considerably optimized resulting in a peak power factor ≈1.8 µW cm−1 K−2 at 873 K, although the carrier concentration is slightly deteriorated. Meanwhile, the lattice thermal conductivity is lowered to ≈0.62 W m−1 K−1 due to the introduction of the second phase. The modified Self‐consistent Effective Medium Theory is utilized to explain the deeper mechanism of modulation doping. The enhancement of apparent carrier mobility is derived from the highly active phase interfaces as fast carrier transport channels, while the reduced apparent thermal conductivity is ascribed to the existence of thermal resistance at the phase interfaces. Ultimately, an optimized ZT ≈0.23 is obtained at 873 K in Bi6Cu2Se3.6Cl0.4O6 + 13% Bi2O2Se. This research demonstrates the effectiveness of modulation doping for optimizing thermoelectric properties once again, and provides the direct microstructure observation and consistent theoretical model calculation to emphasize the role of interface effects in modulation doping, which should be probably applicable to other thermoelectrics.

Enhanced thermoelectric performance of InSb through deep level impurity donor state induced by La doping

As one member of III-V semiconductors that have a variety of applications, InSb also shows great potential in thermoelectrics owing to its high mobility. In this work, the thermoelectric performance of n-type polycrystalline InSb is improved by La doping, which induces deep level impurity donor state and massive defects, synergistically optimizing both electrical and thermal transport properties. The peak power factor of La-doped InSb is enhanced from 42 to 58 μW cm−1 K−2 at 773 K due to the enlarged carrier concentration provided by the deep level donor state. Meanwhile, lattice thermal conductivity decreases from 3.2 to 1.7 W m−1 K−1 at 773 K due to In precipitates, point defects and local atomic disorder. Consequently, the peak zT of La-doped InSb is promoted to 0.85 at 773 K, which is among the best value in III-V compounds.

Effect of post-annealing treatment on the thermoelectric properties of Ag2Se flexible thin film prepared by magnetron sputtering method

Flexible thermoelectric power generation devices can help solve the power supply problem of wearable electronic devices. Herein, single-phase Ag2Se films with a thickness of less than 500 nm were deposited on flexible polyimide substrates via magnetron sputtering. The microstructure, chemical composition, and thermoelectric properties of the films were investigated at different annealing temperatures (523 K–673 K). After annealing, the X-ray diffraction (XRD) test showed that the film had obvious preferential growth in the (002) and (004) crystallographic directions. Scanning electron microscopy (SEM) showed that with increasing annealing temperature, the size of the grains initially increased and subsequently decreased. Finally, after annealing at 623 K for 20 min, the film obtained a peak power factor of 526.86 μW∙m−1∙K−2. A six-leg flexible generator comprising Ag2Se films has a maximum power density of 7.52 W∙m−2 (50 K temperature difference). After 1000 bending times, the resistivity of the device changed by only 14.11 %, and the actual application test revealed an output voltage of 12.3 mV and a power of 23.49 nW under a temperature difference of 22.2 K. This work demonstrates that thermal treatment of thin films prepared by magnetron sputtering is a remarkable approach to increase thermoelectric performance, providing an efficient fabrication scheme for the development of environmentally friendly and wearable flexible thermoelectric devices.

Modulated Fermi Level and Relaxed Lattice Strain Leading to Enhanced Thermoelectric Properties in AgSbSe2

Cubic-phase AgSbSe2 has been known as a decent p-type thermoelectric material, due to its intrinsically low lattice thermal conductivity; nevertheless, the difficulty in modulating its electrical transport performance impeded its further competition with other state-of-the-art mid-temperature thermoelectrics. In this work, we investigated the effects of Pb doping and Sb vacancies on modulating the thermoelectric properties of AgSbSe2. Pb doping was found to be able to obviously increase the hole concentration, leading to a descending of Fermi level well into the multiple valence bands, thus leading to an enhanced band degeneracy; subsequent Sb vacancies could play the role of relaxing the local lattice strains due to PbSb substitution, resulting in a weakened charge carrier scattering and enhanced weighted mobility. Consequently, a peak power factor PFmax of 7.5 μW cm–1 K–2 at 523 K was achieved in the composition of AgSb0.935Pb0.06Se2, which is 40% higher than that of pristine AgSbSe2. Furthermore, Pb doping and Sb vacancies induce enhanced point defect scattering of high-frequency heat-carrying phonons, yielding a reduced lattice thermal conductivity and a remarkably enhanced maximal ZTmax value of 1.02 at 723 K in the sample AgSb0.935Pb0.06Se2.

Improved thermoelectric properties of n-type polycrystalline SnSe via carrier concentration optimization

Polycrystalline SnSe thermoelectric materials have received extensive interests owing to the low thermal conductivity and available mechanical properties. However, the low electrical conductivity seriously hinders its application. In this work, stemming from the introducing of Hf and Cl substitution, they released more electrons. Owing to the improved carrier concentration, a high electrical conductivity of 33 S cm−1 for the SnSe0.95+1 wt%HfCl4 sample was obtained at 773 K, about 5 times as much as that of the SnSe0.95 sample. Thus, a peak power factor of 553.8 μW m−1 K−2 of SnSe0.95+3 wt%HfCl4 sample at 773 K was obtained. Meanwhile, the phonon scattering was enhanced due to the decrease of grain size, the lattice thermal conductivity was suppressed. The pretty low κl of 0.33 W m−1 K−1 was obtained at 773 K for the SnSe0.95+4 wt%HfCl4 sample. Consequently, the peak ZT value of ∼1.1 was achieved for SnSe0.95+3 wt%HfCl4 sample at 773 K.

Lattice expansion enables interstitial doping to achieve a high average ZT in n‐type PbS

AbstractLead sulfide (PbS) presents large potential in thermoelectric application due to its earth‐abundant S element. However, its inferior average ZT (ZTave) value makes PbS less competitive with its analogs PbTe and PbSe. To promote its thermoelectric performance, this study implements strategies of continuous Se alloying and Cu interstitial doping to synergistically tune thermal and electrical transport properties in n‐type PbS. First, the lattice parameter of 5.93 Å in PbS is linearly expanded to 6.03 Å in PbS0.5Se0.5 with increasing Se alloying content. This expanded lattice in Se‐alloyed PbS not only intensifies phonon scattering but also facilitates the formation of Cu interstitials. Based on the PbS0.6Se0.4 content with the minimal lattice thermal conductivity, Cu interstitials are introduced to improve the electron density, thus boosting the peak power factor, from 3.88 μW cm−1 K−2 in PbS0.6Se0.4 to 20.58 μW cm−1 K−2 in PbS0.6Se0.4−1%Cu. Meanwhile, the lattice thermal conductivity in PbS0.6Se0.4−x%Cu (x = 0–2) is further suppressed due to the strong strain field caused by Cu interstitials. Finally, with the lowered thermal conductivity and high electrical transport properties, a peak ZT ~1.1 and ZTave ~0.82 can be achieved in PbS0.6Se0.4 − 1%Cu at 300–773K, which outperforms previously reported n‐type PbS.

Ni doping and rational annealing boost thermoelectric performance of nanostructured double perovskite Pr1.8Sr0.2CoFeO6

Pr2CoFeO6-based double perovskite exhibits intrinsic low thermal conductivity and high Seebeck coefficient, but its low electrical conductivity induces unsatisfied thermoelectric performance. Here, we employ a synergistic strategy of rational annealing and Ni doping to achieve an improved ZT of ∼0.085 at 573 K in Pr1.8Sr0.2CoFe0.95Ni0.05O6, which is ∼425 % higher than that of pristine Pr2CoFeO6. The annealing process effectively reduces pores in the as-sintered bulk material, leading to an enhanced electrical conductivity without damaging the Seebeck coefficient, and the Ni doping further effectively improves the hole carrier concentration and in turn enhances the electrical conductivity, leading to a peak power factor of ∼113 μW m−1 K−2 at 573 K. Besides, Ni doping induces localized crystal imperfections including point defects, dislocations, and lattice distortions, contributing to an ultra-low thermal conductivity of <0.6 W m−1 K−1. As a result, the as-achieved Pr1.8Sr0.2CoFe0.95Ni0.05O6 has a ZT of ∼0.085 at 573 K, which is highly competitive to reported thermoelectric double perovskites, indicating its potential applications in high-performance thermoelectric devices.

Electronic structure and transport property of p-type Mg3Sb2 from first-principles study

Numerous efforts have been paid on n-type Mg3Sb2-based Zintl compounds with exceptional thermoelectric performance, but seldom on p-type sample with poor electrical transports. In this work, we investigate the electronic structure and transport properties of p-type Mg3Sb2 by using first-principles method and Boltzmann transport theory. Firstly, the slightly higher low-temperature electrical conductivity for theoretical calculations than experimental results suggest that different from n-type sample, the contribution of eliminating grain boundary scattering to electrical transports is weak in p-type Mg3Sb2. Secondly, the calculated higher Seebeck coefficient along x-axis and higher electrical conductivity along z-axis reveal the anisotropy of electrical transports, and this phenomenon may be ascribed to the anisotropic carrier's effective masses. Because the gradual leading role of Seebeck coefficient as temperature increasing, the peak power factor along x-axis exceeds that along z-axis at temperature above ∼500 K, which indicates that further improvement of the electrical performance can be expected through anisotropic transports. Thirdly, the effect of the adsorption of oxygen atom on Mg3Sb2 (001) surface on the electronic structure are investigated. This work aims to provide new insight into the optimization of p-type electrical transport property, thereby closing the gap with n-type property for developing Mg3Sb2-based thermoelectric devices.

Improving electrical and thermal properties synchronously via introducing CsPbBr3 QDs into higher manganese silicides

Higher manganese silicide (HMS) is a P-type medium temperature thermoelectric (TE) material, which has attracted widespread attention over the past few decades due to its remarkable mechanical properties, excellent chemical and thermal stability, as well as the non-toxicity, abundance and competitive price. The peak power factor (PF) of HMS is as high as ∼1.50 × 10−3 W m−1 K−2 because of its intrinsic high electrical conductivity and Seebeck coefficient. However, the thermal conductivity of HMS is also high, resulting in relatively low zT values. Introducing nano-dispersion in the matrix is one of the most effective methods to enhance the TE properties via reducing the lattice thermal conductivity significantly without drastic changes on the other parameters. In this study, CsPbBr3 QDs with uniform size were synthesized and introduced into HMS bulks. The PF (at 823 K) was enhanced to 1.71 × 10−3 W m−1 K−2, which is improved 14.0% approximately compared with that of pure HMS owing to the combined effect of element doping and energy filtering. The lattice thermal conductivity (at 823 K) decreased from 2.56 W m−1 K−1 to 1.99 W m−1 K−1 synchronously (∼22.0%) due to the intensive phonon scattering caused by Cs doping, and the embedding of Pb riched CsPbBr3 QDs and Pb QDs. A maximum zT value of 0.57 (823 K) is achieved in CsPbBr3 QDs/HMS composites, which is 36.0% higher than that of pure HMS. Predictably, for other TE materials, it is also feasible to improve the TE properties via introducing metastable quantum dots.

Thermoelectric Performance of n-Type Magnetic Element Doped Bi2S3.

Thermoelectric technology offers great potential for converting waste heat into electrical energy and is an emission-free technique for solid-state cooling. Conventional high-performance thermoelectric materials such as Bi2Te3 and PbTe use rare or toxic elements. Sulfur is an inexpensive and nontoxic alternative to tellurium. However, achieving high efficiencies with Bi2S3 is challenging due to its high electrical resistivity that reduces its power factor. Here, we report Bi2S3 codoped with Cr and Cl to enhance its thermoelectric properties. An enhanced conductivity was achieved due to an increase in the carrier concentration by the substitution of S with Cl. High values of the Seebeck coefficients were obtained despite high carrier concentrations; this is attributed to an increase in the effective mass, resulting from the magnetic drag introduced by the magnetic Cr dopant. A peak power factor of 566 μW m–1 K–2 was obtained for a cast sample of Bi2–x/3Crx/3S3–xClx with x = 0.01 at 320 K, as high as the highest values reported in the literature for sintered samples. These results support the success of codoping thermoelectric materials with isovalent magnetic and carrier concentration tuning elements to enhance the thermoelectric properties of eco-friendly materials.