Multi-heterojunctioned plastics with high thermoelectric figure of merit.

Conjugated polymers promise inherently flexible and low-cost thermoelectrics for powering the Internet of Things from waste heat1,2. Their valuable applications, however, have been hitherto hindered by the low dimensionless figure of merit (ZT)3-6. Here we report high-ZT thermoelectric plastics, which were achieved by creating a polymeric multi-heterojunction with periodic dual-heterojunction features, where each period is composed of two polymers with a sub-ten-nanometre layered heterojunction structure and an interpenetrating bulk-heterojunction interface. This geometry produces significantly enhanced interfacial phonon-like scattering while maintaining efficient charge transport. We observed a significant suppression of thermal conductivity by over 60 per cent and an enhanced power factor when compared with individual polymers, resulting in a ZT of up to 1.28 at 368 kelvin. This polymeric thermoelectric performance surpasses that of commercial thermoelectric materials and existing flexible thermoelectric candidates. Importantly, we demonstrated the compatibility of the polymeric multi-heterojunction structure with solution coating techniques for satisfying the demand for large-area plastic thermoelectrics, which paves the way for polymeric multi-heterojunctions towards cost-effective wearable thermoelectric technologies.

Interstitials in Thermoelectrics.

Defect structure is pivotal in advancing thermoelectric performance with interstitials being widely recognized for their remarkable roles in optimizing both phonon and electron transport properties. Diverse interstitial atoms are identified in previous works according to their distinct roles and can be classified into rattling interstitial, decoupling interstitial, interlayer interstitial, dynamic interstitial, and liquid interstitial. Specifically, rattling interstitial can cause phonon resonance in cage compound to scatter phonon transport; decoupling interstitial can contribute to phonon blocking and electron transport due to their significantly different mean free paths; interlayer interstitial can facilitate out-of-layer electron transport in layered compounds; dynamic interstitial can tune temperature-dependent carrier density and optimize electrical transport properties at wide temperatures; liquid interstitial could improve the carrier mobility at homogeneous dispersion state. All of these interstitials have positive impact on thermoelectric performance by adjusting transport parameters. This perspective therefore intends to provide a thorough overview of advances in interstitial strategy and highlight their significance for optimizing thermoelectric parameters. Finally, the profound potential for extending interstitial strategy to various other thermoelectric systems is discussed and some future directions in thermoelectric material are also outlined.

Realizing thermoelectric cooling and power generation in N-type PbS0.6Se0.4 via lattice plainification and interstitial doping.

Thermoelectrics have great potential for use in waste heat recovery to improve energy utilization. Moreover, serving as a solid-state heat pump, they have found practical application in cooling electronic products. Nevertheless, the scarcity of commercial Bi2Te3 raw materials has impeded the sustainable and widespread application of thermoelectric technology. In this study, we developed a low-cost and earth-abundant PbS compound with impressive thermoelectric performance. The optimized n-type PbS material achieved a record-high room temperature ZT of 0.64 in this system. Additionally, the first thermoelectric cooling device based on n-type PbS was fabricated, which exhibits a remarkable cooling temperature difference of ~36.9 K at room temperature. Meanwhile, the power generation efficiency of a single-leg device employing our n-type PbS material reaches ~8%, showing significant potential in harvesting waste heat into valuable electrical power. This study demonstrates the feasibility of sustainable n-type PbS as a viable alternative to commercial Bi2Te3, thereby extending the application of thermoelectrics.

High Carrier Mobility and Promising Thermoelectric Module Performance of N-Type PbSe Crystals.

The scarcity of Te hampers the widespread use of Bi2Te3-based thermoelectric modules. Here, the thermoelectric module potential of PbSe is investigated by improving its carrier mobility. Initially, large PbSe crystals are grown with the temperature gradient method to mitigate grain boundary effects on carrier transport. Subsequently, light doping with <1mole‰ halogens (Cl/Br/I) increases room-temperature carrier mobility to ~1600 cm2 V-1 s-1, achieved by reducing carrier concentration compared to traditional heavy doping. Crystal growth design and light doping enhance carrier mobility without affecting effective mass, resulting in a high power factor ~40 µW cm-1 K-2 in PbSe-Cl/Br/I crystals at 300 K. Additionally, Cl/Br/I doping reduces thermal conductivity and bipolar diffusion, leading to significantly lower thermal conductivity at high temperature. Enhanced carrier mobility and suppressed bipolar effect boost ZT values across the entire temperature range in n-type PbSe-Cl/Br/I crystals. Specifically, ZT values of PbSe-Br crystal reach ~0.6 at 300 K, ~1.2 at 773 K, and the average ZT (ZTave) reaches ~1.0 at 300-773 K. Ultimately, ~5.8% power generation efficiency in a PbSe single leg with a maximum temperature cooling difference of 40 K with 7-pair modules is achieved. These results indicate the potential for cost-effective and high-performance thermoelectric cooling modules based on PbSe.

Realizing high-efficiency thermoelectric module by suppressing donor-like effect and improving preferred orientation in n-type Bi2(Te, Se)3.

Thermoelectric materials have a wide range of application because they can be directly used in refrigeration and power generation. And the Bi2Te3 stand out because of its excellent thermoelectric performance and are used in commercial thermoelectric devices. However, n-type Bi2Te3 has seriously hindered the development of Bi2Te3-based thermoelectric devices due to its weak mechanical properties and inferior thermoelectric performance. Therefore, it is urgent to develop a high-performance n-type Bi2Te3 polycrystalline. In this work, we employed interstitial Cu and the hot deformation process to optimize the thermoelectric properties of Bi2Te2.7Se0.3, and a high-performance thermoelectric module was fabricated based on this material. Our combined theoretical and experimental effort indicates that the interstitial Cu reduce the defect density in the matrix and suppresses the donor-like effect, leading to a lattice plainification effect in the material. In addition, the two-step hot deformation process significantly improves the preferred orientation of the material and boosts the mobility. As a result, a maximum ZT of 1.27 at 373 K and a remarkable high ZTave of 1.22 across the temperature range of 300-425 K are obtained. The thermoelectric generator (TEG, 7-pair) and thermoelectric cooling (TEC, 127-pair) modules were fabricated with our n-type textured Cu0.01Bi2Te2.7Se0.3 coupled with commercial p-type Bi2Te3. The TEC module demonstrates superior cooling efficiency compared with the commercial Bi2Te3 device, achieving a ΔT of 65 and 83.4 K when the hot end temperature at 300 and 350 K, respectively. In addition, the TEG module attains an impressive conversion efficiency of 6.5% at a ΔT of 225 K, which is almost the highest value among the reported Bi2Te3-based TEG modules.

Expression of lncRNA LINC00943 in lung squamous cell carcinoma and its relationship with tumor progression.

BACKGROUND: Molecular biology has been applied to the diagnosis, prognosis and treatment of various diseases, and long noncoding RNA LINC00943 (lncRNA LINC00943; LINC00943) plays an important role in a variety of cancers. Therefore, this study explored the prognostic role of LINC00943 in lung squamous cell carcinoma (LUSC) and understood its impact on the development of LUSC. METHODS: There are 89 LUSC patients were involved in current assay. By detecting the expression of LINC00943 and miR-196b-5p in tissues and cells, LINC00943 and its correlation with the characteristics of clinical data were analyzed. The biological function of LINC00943 was studied by Transwell migration and invasion assays. In addition, Pearson correlation coefficient and luciferase activity experiments were chosen to characterize the relationship between LINC00943 and miR-196b-5p and explore the mechanism of LINC00943. RESULTS: Compared with normal controls, LINC00943 expression in LUSC tissues and cells was significantly reduced, miR-196b-5p was markedly increased, there was a negative correlation between LINC00943 and miR-196b-5p. According to the in vitro cell experiments, migration and invasion of LUSC cells were suppressed by overexpression of LINC00943. Besides, LINC00943 was demonstrated to have prognostic power and targeting miR-196b-5p was involved in the progression of LUSC. CONCLUSIONS: Overexpression of LINC00943 was molecular sponge for miR-196b-5p that controlled the deterioration of LUSC, which had great potential as a prognostic biomarker for LUSC.

[Clinical Efficacy and Safety of Ixazomib-Containing Regimens in the Treatment of Patients with Multiple Myeloma].

OBJECTIVE: To investigate the clinical efficacy and safety of ixazomib-containing regimens in the treatment of patients with multiple myeloma (MM). METHODS: A retrospective analysis was performed on the clinical efficacy and adverse reactions of 32 MM patients treated with a combined regimen containing ixazomib in the Hematology Department of the First People's Hospital of Lianyungang from January 2020 to February 2022. Among the 32 patients, 15 patients were relapsed and refractory multiple myeloma (R/RMM) (R/RMM group), 17 patients who responded to bortezomib induction therapy but converted to ixazomib-containing regimen due to adverse events (AE) or other reasons (conversion treatment group). The treatment included IPD regimen (ixazomib+pomalidomide+dexamethasone), IRD regimen (ixazomib+lenalidomide+dexamethasone), ICD regimen (ixazomib+cyclophosphamide+dexamethasone), ID regimen (ixazomib+dexamethasone). RESULTS: Of 15 R/RMM patients, overall response rate (ORR) was 53.3%(8/15), among them, 1 achieved complete response (CR), 2 achieved very good partial response (VGPR) and 5 achieved partial response (PR). The ORR of the IPD, IRD, ICD and ID regimen group were 100%（3/3）, 42.9%（3/7）, 33.3%（1/3）, 50%（1/2）， respectively， there was no statistically significant difference in ORR between four groups (χ 2=3.375, P =0.452). The ORR of patients was 50% after first-line therapy, 42.9% after second line therapy, 60% after third line therapy or more, with no statistically significant difference among them (χ2=2.164, P =0.730). In conversion treatment group, ORR was 88.2%(15/17), among them, 6 patients achieved CR, 5 patients achieved VGPR and 4 patients achieved PR. There was no statistically significant difference in ORR between the IPD（100%， 3/3）, IRD（100%， 6/6）, ICD（100%， 3/3） and ID（60%， 3/5） regimen groups (χ2=3.737，P =0.184). The median progression-free survival (PFS) time of R/RMM patients was 9 months (95% CI : 6.6-11.4 months), the median overall survival (OS) time was 18 months (95% CI : 11.8-24.4 months). The median PFS time of conversion treatment group was 15 months (95% CI : 7.3-22.7 months), the median OS time not reached. A total of 10 patients suffered grade 3- 4 adverse event (AE). The common hematological toxicities were leukocytopenia, anemia, thrombocytopenia. The common non-hematological toxicities were gastrointestinal symptoms (diarrhea, nausea and vomit), peripheral neuropathy, fatigue and infections. Grade 1-2 peripheral neurotoxicity occurred in 7 patients. CONCLUSION: The ixazomib-based chemotherapy regimens are safe and effective in R/RMM therapy, particularly for conversion patients who are effective for bortezomib therapy. The AE was manageable and safe.

Lattice Plainification Leads to High Thermoelectric Performance of P-Type PbSe Crystals.

Thermoelectrics has applications in power generation and refrigeration. Since only commercial Bi2Te3 has a low abundance Te, PbSe gets attention. This work enhances the near-room temperature performance of p-type PbSe through enhancing carrier mobility via lattice plainification. Composition controlled and Cu-doped p-type PbSe crystals are grown through physical vapor deposition. Results exhibit an enhanced carrier mobility ≈2578 cm2 V-1 s-1 for Pb0.996Cu0.0004Se. Microstructure characterization and density functional theory calculations verify the introduced Cu atoms filled Pb vacancies, realizing lattice plainification and enhancing the carrier mobility. The Pb0.996Cu0.0004Se sample achieves a power factor ≈42 µW cm-1 K-2 and a ZT ≈ 0.7 at 300 K. The average ZT of it reaches ≈0.9 (300-573 K), resulting in a single-leg power generation efficiency of 7.1% at temperature difference of 270 K, comparable to that of p-type commercial Bi2Te3. A 7-pairs device paired the p-type Pb0.996Cu0.0004Se with the n-type commercial Bi2Te3 shows a maximum cooling temperature difference ≈42 K with the hot side at 300 K, ≈65% of that of the commercial Bi2Te3 device. This work highlights the potential of p-type PbSe for power generation and refrigeration near room temperature and hope to inspire researchers on replacing commercial Bi2Te3.

All-SnTe-Based Thermoelectric Power Generation Enabled by Stepwise Optimization of n-Type SnTe.

The practical application of thermoelectric devices requires both high-performance n-type and p-type materials of the same system to avoid possible mismatches and improve device reliability. Currently, environmentally friendly SnTe thermoelectrics have witnessed extensive efforts to develop promising p-type transport, making it rather urgent to investigate the n-type counterparts with comparable performance. Herein, we develop a stepwise optimization strategy for improving the transport properties of n-type SnTe. First, we improve the n-type dopability of SnTe by PbSe alloying to narrow the band gap and obtain n-type transport in SnTe with halogen doping over the whole temperature range. Then, we introduce additional Pb atoms to compensate for the cationic vacancies in the SnTe-PbSe matrix, further enhancing the electron carrier concentration and electrical performance. Resultantly, the high-ranged thermoelectric performance of n-type SnTe is substantially optimized, achieving a peak ZT of ∼0.75 at 573 K with a high average ZT (ZTave) exceeding 0.5 from 300 to 823 K in the (SnTe0.98I0.02)0.6(Pb1.06Se)0.4 sample. Moreover, based on the performance optimization on n-type SnTe, for the first time, we fabricate an all-SnTe-based seven-pair thermoelectric device. This device can produce a maximum output power of ∼0.2 W and a conversion efficiency of ∼2.7% under a temperature difference of 350 K, demonstrating an important breakthrough for all-SnTe-based thermoelectric devices. Our research further illustrates the effectiveness and application potential of the environmentally friendly SnTe thermoelectrics for mid-temperature power generation.

Thermoelectrocatalysis: an emerging strategy for converting waste heat into chemical energy.

This perspective defines and explores an innovative waste heat harvesting strategy, thermoelectrocatalysis (TECatal), emphasizing materials design and potential applications in clean energy, environmental, and biomedical technologies.

Grid-plainification enables medium-temperature PbSe thermoelectrics to cool better than Bi2Te3.

Thermoelectric cooling technology has important applications for processes such as precise temperature control in intelligent electronics. The bismuth telluride (Bi2Te3)-based coolers currently in use are limited by the scarcity of Te and less-than-ideal cooling capability. We demonstrate how removing lattice vacancies through a grid-design strategy switched PbSe from being useful as a medium-temperature power generator to a thermoelectric cooler. At room temperature, the seven-pair device based on n-type PbSe and p-type SnSe produced a maximum cooling temperature difference of ~73 kelvin, with a single-leg power generation efficiency approaching 11.2%. We attribute our results to a power factor of >52 microwatts per centimeter per square kelvin, which was achieved by boosting carrier mobility. Our demonstration suggests a path for commercial applications of thermoelectric cooling based on Earth-abundant Te-free selenide-based compounds.

Prognostic value of the peripheral blood lymphocyte/monocyte ratio combined with 18F-FDG PET/CT in patients with diffuse large B-cell lymphoma.

OBJECTIVE: To explore the prognostic value of the peripheral blood lymphocyte/monocyte ratio (LMR) combined with 18F-FDG PET/CT for diffuse large B-cell lymphoma (DLBCL). METHODS: The clinical data of 203 patients with primary DLBCL who were hospitalized to the First People's Hospital of Lianyungang between January 2017 and December 2022 were retrospectively analyzed. Before and after three courses of treatment, PET/CT was performed on forty DLBCL patients. The subject operating characteristic (ROC) curve has been employed to determine the most effective LMR cutoff points. According to the criteria for assessing the efficacy of Lugano lymphoma, the PET/CT findings after 3 courses of treatment were specified as complete remission (CR), partial remission (PR), stable disease (SD) and disease progression (PD). The CR group, PR+SD group, and PD group were the three groups created from the four outcomes. Results were analyzed using the Cox proportional risk model, the Kaplan-Meier method (K-M), and the log-rank test. RESULTS: An optimal cutoff point of 3.00 for the LMR in 203 patients was determined by the SPSS 26 software ROC curve. When LMR≥3.00, the 1-year, 3-year, and 5-year OS (Overall Survival) rates are 98%, 88%, and 64% respectively, and the PFS (Progression-free Survival) rates are 90%, 75%, and 56% respectively. When LMR <3.00, the 1-year, 3-year, and 5-year OS rates are 96%, 72%, and 28% respectively, and the PFS rates are 83%, 60%, and 28% respectively. A lower LMR was substantially related with shorter OS, and PFS, according to a K-M survival analysis (P<0.005). LMR<3.00 was an independent predictor of OS, based on a multifactorial Cox analysis (P=0.037). K-M survival analysis of the 18F-FDG PET/CT results of 40 patients revealed that both OS and PFS were statistically significant (P<0.001). Patients were separated into 3 groups combining LMR and 18F-FDG PET/CT: PET/CT CR patients with LMR≥3.00, PET/CT PD patients with LMR<3.00, and others. The Kaplan-Meier analysis revealed that there were significant differences in OS and PFS for each of the three groups (P<0.001). ROC curves showed that the area under the curve (AUC) of the combined testing of the two was 0.735, and the combined testing of the two was better compared to testing alone (PET/CT AUC=0.535, LMR AUC=0.567). This indicates that combining both PET/CT and LMR is a favorable prediction for DLBCL. CONCLUSION: A decreased LMR at initial diagnosis suggests an unfavorable prognosis for DLBCL patients; For patients with DLBCL, combining 18F-FDG PET/CT and the LMR has a better predictive value.

A Novel Splicing Mutation Leading to Wiskott-Aldrich Syndrome from a Family.

Wiskott-Aldrich syndrome (WAS) is a rare X-linked recessive genetic disease characterized by clinical symptoms such as eczema, thrombocytopenia with small platelets, immune deficiency, prone to autoimmune diseases, and malignant tumors. This disease is caused by mutations of the WAS gene encoding WASprotein (WASP). The locus and type of mutations of the WAS gene and the expression quantity of WASP were strongly correlated with the clinical manifestations of patients. We found a novel mutation in the WAS gene (c.931 + 5G > C), which affected splicing to produce three abnormal mRNA, resulting in an abnormally truncated WASP. This mutation led to a reduction but not the elimination of the normal WASP population, resulting in causes X-linked thrombocytopenia (XLT) with mild clinical manifestations. Our findings revealed the pathogenic mechanism of this mutation.

Metformin and chidamide synergistically suppress multiple myeloma progression and enhance lenalidomide/bortezomib sensitivity.

Multiple myeloma (MM) is a common hematological malignancy, and patients with MM are recommended to take immunomodulatory drugs such as lenalidomide along with proteasome inhibitors such as bortezomib to extend survival. However, drug resistance influences the efficacy of treatment for MM. In our study, we found that metformin and chidamide both suppressed MM cell growth in a concentration- and time-dependent way (p < .001). Moreover, combined therapy with metformin and chidamide exhibited enhanced inhibition of the growth of MM cells compared with monotherapy (p < .05). Additionally, the triple-drug combination of metformin and chidamide with lenalidomide or bortezomib was used to stimulate the MM cells, and the results revealed that metformin and chidamide treatment sensitized MM cells to lenalidomide and bortezomib. As a result, the apoptosis (p < .001) together with cell cycle arrest at G0/G1 phase (p < .05) was stimulated by lenalidomide and bortezomib, and showed significant elevation in the triple-drug combination group compared with the lenalidomide or bortezomib treatment alone group (p < .05). Furthermore, the impacts of different drugs on glycolysis in MM cells were examined. We found that metformin and chidamide combined treatment significantly promoted glucose uptake and reduced energy production in MM cells treated with lenalidomide and bortezomib (p < .001), suggesting that metformin and chidamide affected glycolysis in MM cells and enhanced the sensitivity of lenalidomide and bortezomib in MM by regulating glucose metabolism. In conclusion, metformin and chidamide synergistically hindered MM cell growth and sensitized cells to lenalidomide/bortezomib. The findings of this study might provide novel clues to improve MM therapy.

Targeted genome engineering based on CRISPR/Cas9 system to enhance FVIII expression in vitro.

BACKGROUND: Hemophilia A is caused by a deficiency of coagulation factor VIII in the body due to a defect in the F8 gene. The emergence of CRISPR/Cas9 gene editing technology will make it possible to alter the expression of the F8 gene in hemophiliacs, while achieving a potential cure for the disease. METHODS: Initially, we identified high-activity variants of FVIII and constructed donor plasmids using enzymatic digestion and ligation techniques. Subsequently, the donor plasmids were co-transfected with sgRNA-Cas9 protein into mouse Neuro-2a cells, followed by flow cytometry-based cell sorting and puromycin selection. Finally, BDD-hF8 targeted to knock-in the mROSA26 genomic locus was identified and validated for FVIII expression. RESULTS: We identified the p18T-BDD-F8-V3 variant with high FVIII activity and detected the strongest pX458-mROSA26-int1-sgRNA1 targeted cleavage ability and no cleavage events were found at potential off-target sites. Targeted knock-in of BDD-hF8 cDNA at the mROSA26 locus was achieved based on both HDR/NHEJ gene repair approaches, and high level and stable FVIII expression was obtained, successfully realizing gene editing in vitro. CONCLUSIONS: Knock-in of exogenous genes based on the CRISPR/Cas9 system targeting genomic loci is promising for the research and treatment of a variety of single-gene diseases.

Prognostic value of lactate dehydrogenase, serum albumin and the lactate dehydrogenase/albumin ratio in patients with diffuse large B-cell lymphoma.

OBJECTIVE: To investigate the prognostic value of lactate dehydrogenase (LDH), serum albumin (ALB) and the lactate dehydrogenase/albumin ratio (LAR) in diffuse large B-cell lymphoma (DLBCL) before primary treatment. METHODS: The clinical data of 212 primary adult DLBCL patients admitted to the First People's Hospital of Lianyungang from January 2017 to December 2022 were analyzed retrospectively. The optimal cutoff values of LDH, ALB, and LAR were determined using ROC curves. Survival curves of LDH, ALB, and LAR were plotted and analyzed using the Cox regression model and Kaplan-Meier method with the log-rank test. RESULTS: Among the 212 patients admitted, the study derived the optimal cutoff values for ALB, LDH, and LAR as 38, 301, and 6, respectively. The Kaplan-Meier method and log-rank test analysis indicated a significant association between lower ALB levels, elevated LDH levels, elevated LAR levels, and shorter overall survival (OS) and progression-free survival (PFS) (P < 0.05). Additionally, the critical values of ALB and LDH were grouped into three categories. The differences in OS and PFS among these three groups were statistically significant (P < 0.05). Cox multifactorial analysis revealed that the LAR was an independent factor influencing the prognosis of OS and PFS, with a higher prognostic value than LDH and ALB alone. CONCLUSION: Decreased ALB levels and elevated LDH and LAR levels at the time of initial diagnosis are indicative of a poor prognosis in DLBCL patients. Furthermore, the study highlighted that the LAR has a higher prognostic value than LDH and ALB alone.

Seismic performance and bearing capacity calculation of cross shaped concrete columns with built-in T-shaped steel and steel tubes.

Incorporating T-shaped steel and square steel tubes into a cross shaped concrete column can significantly improve the seismic performance of the cross shaped column. However, the experimental samples are limited, so ABAQUS finite element (FE) analysis method was adopted in this paper to study the seismic performance of this cross shaped column, calculate and verify three specimens in the existing reference. Based on the reliable model, parameter analysis was carried out (25 specimens in total). The results show that the established model has a high degree of coincidence in the hysteretic curve, skeleton curve and failure mode, and the error of ultimate bearing capacity and ductility is within 10%. The configuration of T-shaped steel and square steel tubes inside the cross column can meet the ductility requirements specified in the standard under high axial compression ratio. The ultimate bearing capacity of the cross shaped column increases with the increase of the thickness of the square steel tube, but the ductility deteriorates. The increase in steel tube size increases the strength of the concrete in the core area, and the seismic performance of the cross shaped column was improved. Increasing the thickness of the T-shaped steel flange can better improve the seismic performance of the cross shaped column compared to increasing the thickness of the T-shaped steel web plate. Increasing the height of the specimen will significantly reduce its seismic performance. When the shear span ratio is not greater than 4.1, the ductility can meet the standard requirements. The error of the formula for calculating the compression-bending bearing capacity proposed based on existing calculation methods is less than 5%.

Large Mobility Enables Higher Thermoelectric Cooling and Power Generation Performance in n-type AgPb18+xSbTe20 Crystals.

The room-temperature thermoelectric performance of materials underpins their thermoelectric cooling ability. Carrier mobility plays a significant role in the electronic transport property of materials, especially near room temperature, which can be optimized by proper composition control and growing crystals. Here, we grow Pb-compensated AgPb18+xSbTe20 crystals using a vertical Bridgman method. A large weighted mobility of ∼410 cm2 V-1 s-1 is achieved in the AgPb18.4SbTe20 crystal, which is almost 4 times higher than that of the polycrystalline counterpart due to the elimination of grain boundaries and Ag-rich dislocations verified by atom probe tomography, highlighting the significant benefit of growing crystals for low-temperature thermoelectrics. Due to the largely promoted weighted mobility, we achieve a high power factor of ∼37.8 µW cm-1 K-2 and a large figure of merit ZT of ∼0.6 in AgPb18.4SbTe20 crystal at 303 K. We further designed a 7-pair thermoelectric module using this n-type crystal and a commercial p-type (Bi, Sb)2Te3-based material. As a result, a high cooling temperature difference (ΔT) of ∼42.7 K and a power generation efficiency of ∼3.7% are achieved, revealing promising thermoelectric applications for PbTe-based materials near room temperature.

Constructing quasi-layered and self-hole doped SnSe oriented films to achieve excellent thermoelectric power factor and output power density.

Thermoelectric (TE) technology can achieve the mutual conversion between electric energy and waste heat, and it has exhibited great prospects in multifunctional energy applications to alleviate the energy crisis. In the recent decade, SnSe has been explored widely because of its potentially high energy harvesting efficiency, green nature, and low cost. However, the relatively poor power factor (PF) derived from the intrinsic low carrier concentration (∼1017 cm-3) limits the output power density of the stoichiometric SnSe devices. Therefore, the advancement of novel optimization strategies for controlling carrier concentration is of utmost importance. Besides, compared with 3D bulks, 2D thin films are more compatible with modern semiconductor technology and have unique advantages in the construction and application of TE micro- and nano-devices. In this study, post-selenization technology were applied to increase the carrier concentration of the a-axis oriented SnSe epitaxial films utilizing the charge transfer and self-hole doped effects. The quasi-layered and self-hole doped films exhibited a high power factor of ∼5.9 µW cm-1 K-2 at 600 K along the in-plane direction when the carrier concentration is enhanced to ∼1018 cm-3 by increasing the selenization time to ∼20 min. The TE generator composed of four P-type film legs demonstrated the ultrahigh maximum power density of ∼83, ∼838 µW cm-2 at the temperature difference of ∼50 and ∼90 K, respectively. Post-selenization can effectively optimize the carrier concentration of SnSe-based materials, which is also feasible to other anion deficient TE films.

Rethinking SnSe Thermoelectrics from Computational Materials Science.

ConspectusThe growing energy crisis and the adverse environmental impacts caused by carbon-based energy consumption have spurred the exploration of green and sustainable energy. Researchers have been devoted to developing thermoelectric technology that could directly and reversibly convert heat into electricity. By virtue of zero emissions, nonmoving parts, precise temperature control, and long service life, thermoelectrics exhibit broad application in power generation and refrigeration. Nevertheless, traditional narrow-bandgap thermoelectrics exhibit high performance within a narrow temperature range, limiting the overall energy conversion. Consequently, a selection rule for exploring advanced thermoelectrics was proposed: materials with wide-bandgap, crystals form, asymmetry, and anisotropic structure. According to the rules, we conducted much research and found some promising materials.As the lead-free, cost-effective, and stable thermoelectric candidates, layered SnSe crystals with wide-bandgap and covalent bonding have gained significant attention due to their ultralow thermal conductivity resulting from strong bonding anharmonicity, via strong polar covalent bonding, because of the electronegativity difference between the Sn and Se atoms. This was proved to be the result from the unique structure of layered SnSe crystals, a distorted rock-salt structure with high and anisotropic Grüneisen parameters. In this Account, we introduce and rethink our recent advancements in developing high-performance thermoelectric SnSe crystals from computational materials science, involving p- and n-type SnSe crystals, respectively. For p-type SnSe crystals, according to the complex valence band structures, we utilized the multiband synglisis via electronic structure calculations and multiband simulations to activate valence bands to participate in electrical transport of in-plane direction, achieving an ultrahigh power factor (PF) of ∼75 µW cm-1 K-2 at room temperature and an average figure-of-merit ZTave of ∼1.9 for Sn0.91Pb0.09Se. Besides, on the basis of defect chemistry, the characteristics of p-type SnSe crystals are determined by intrinsic Sn vacancies. We thus used point-defect calculations to achieve the lattice plainification, and we fixed the lattice intrinsic defects to weaken defect scattering of carriers along the in-plane direction, facilitating further a PF > 100 µW cm-1 K-2 and a ZT of ∼1.5 at room temperature for SnCu0.001Se. For n-type SnSe crystals, inspired by the anisotropic characteristics of the layered materials, we analyzed charge density and proposed the insight of 3D charge and 2D phonon transports and calculated the deformation potential to manipulate layered phonon-electron decoupling to achieve high performance, ultimately Pb-alloyed and Cl-doped SnSe (SnSe-Cl-PbSe) reaching a ZTave of ∼1.7 from 300 to 773 K. In the end, we offer potential perspectives on high-throughput calculations (HTC) and machine learning (ML), combined with our proposed insights, which could be a promising avenue for future thermoelectrics. By virtue of our theoretical and experimental understanding of thermoelectrics, integrating these insights as rules and descriptors for HTC and ML will accelerate the research and development of thermoelectrics. We want to share our recent works and latest perspectives in SnSe thermoelectrics, and we expect to inspire enthusiasm for innovative research on advanced thermoelectric materials and devices.