High Seebeck Coefficient in Mixtures of Conjugated Polymers

A universal method to obtain record‐high electronic Seebeck coefficients is demonstrated while preserving reasonable conductivities in doped blends of organic semiconductors through rational design of the density of states (DOSs). A polymer semiconductor with a shallow highest occupied molecular orbital (HOMO) level‐poly(3‐hexylthiophene) (P3HT) is mixed with materials with a deeper HOMO (PTB7, TQ1) to form binary blends of the type P3HT_x:B_1‐x (0 ≤ x ≤ 1) that is p‐type doped by F₄TCNQ. For B = PTB7, a Seebeck coefficient S = 1100 µV K^?1 with conductivity σ = 0.3 S m^?1 at x = 0.10 is achieved, while for B = TQ1, S = 2000 µV K^?1 and σ = 0.03 S m^?1 at x = 0.05 is found. Kinetic Monte Carlo simulations with parameters based on experiments show good agreement with the experimental results, confirming the intended mechanism. The simulations are used to derive a design rule for parameter tuning. These results can become relevant for low‐power, low‐cost applications like (providing power to) autonomous sensors, in which a high Seebeck coefficient translates directly to a proportionally reduced number of legs in the thermogenerator, and hence in reduced fabrication cost and complexity.     

Conductive Nanostructures of MMX Chains

Crystals of [Pt₂(n‐pentylCS₂)₄I] show a transition from semiconductor to metallic with the increase of the temperature (conductivity is 0.3–1.4 S · cm^?1 at room temperature) and a second metallic–metallic transition at 330 K, inferred by electrical conductivity measurements. X‐ray diffraction studies carried out at different temperatures (100, 298, and 350 K) confirm the presence of three different phases. The valence‐ordering of these phases is analyzed using structural, magnetic, and electrical data. Density functional theory calculations allow a further analysis of the band structure derived for each phase. Nanostructures adsorbed on an insulating surface show electrical conductivity. These results suggest that MMX‐polymer‐based nanowires could be suitable for device applications.     

Flexible 3D Porous MoS2/CNTs Architectures with ZT of 0.17 at Room Temperature for Wearable Thermoelectric Applications

Developing materials that possess high electrical conductivities (σ) and Seebeck coefficients (S), low thermal conductivities (κ), and excellent mechanical properties is important to realize practical thermoelectric (TE) devices. Here, 3D hierarchical architectures consisting of hybrid molybdenum disulfide (MoS₂)/carbon nanotubes (CNTs) films are fabricated with the goal of increasing σ and decreasing κ. In these films, perpendicularly orientated CNTs interpenetrate restacked MoS₂ layers to form a 3D architecture, which increases the specific surface area and charge concentration. The MoS₂/20 wt% CNTs film shows high σ (235 ± 5 S?cm^?1), high S (68 ± 2 µV?K^?1), and low κ (19 ± 2 mW?m^?1?K^?1). The corresponding figure of merit (ZT) reaches 0.17 at room temperature, which is 65 times higher than that of pure MoS₂ film. In addition, the MoS₂/20 wt% CNTs film shows a tensile stress of 38.9 MPa, which is an order of magnitude higher than that of a control MoS₂ film. Using the MoS₂/CNTs film as an active material and human body as a heat source, a flexible, wearable TE wristband is fabricated by weaving seven strips of the 3D porous MoS₂/CNTs film. The wristband achieves an output voltage of 2.9 mV and corresponding power output of 0.22 µW at a temperature gradient of about 5 K.     

The Formation of Performance Enhancing Pseudo‐Composites in the Highly Active La1–xCaxFe0.8Ni0.2O3 System for IT‐SOFC Application

The La_1–xCa_xFe_0.8Ni_0.2O_3–δ (0 ≤ x ≤ 0.9) system is investigated for potential application as a cathode material for intermediate temperature solid oxide fuel cells (IT‐SOFCs). A broad range of experimental techniques have been utilized in order to elucidate the characteristics of the entire compositional range. Low A‐site Ca content compositions (x ≤ 0.4) feature a single perovskite solid solution. Compositions with 40% Ca content (x = 0.4) exhibit the highest electrical and ionic conductivities of these single phase materials (250 and 1.9 × 10^?3 S cm^?1 at 800 °C, respectively), a level competitive with state‐of‐the‐art (La,Sr)(Fe,Co)O₃. Between 40 and 50% Ca content (0.4 > x > 0.5) a solubility limit is reached and a secondary, brownmillerite‐type phase appears for all higher Ca content compositions (0.5 ≤ x ≤ 0.9). While typically seen as detrimental to electrochemical performance in cathode materials, this phase brings with it ionic conductivity at operational temperatures. This gives rise to the effective formation of pseudo‐composite materials which feature significantly enhanced performance characteristics, while also providing the closest match in thermal expansion behavior to typical electrolyte materials. This all comes with the advantage of being produced through a simple, single‐step, low‐cost production route without the issues associated with typical composite materials. The highest performing pseudo‐composite material (x = 0.5) exhibits electronic conductivity of 300–350 S cm^?1 in the 600–800 °C temperature range while the best polarisation resistance (R_p) values of approximately 0.2 Ω cm² are found in the 0.5 ≤ x ≤ 0.7 range.     

Intrinsically Low Thermal Conductivity in BiSbSe3: A Promising Thermoelectric Material with Multiple Conduction Bands

Bi₂Se₃, as a Te‐free alternative of room‐temperature state‐of‐the‐art thermoelectric (TE) Bi₂Te₃, has attracted little attention due to its poor electrical transport properties and high thermal conductivity. Interestingly, BiSbSe₃, a product of alloying 50% Sb on Bi sites, shows outstanding electron and phonon transports. BiSbSe₃ possesses orthorhombic structure and exhibits multiple conduction bands, which can be activated when the carrier density is increased as high as ≈3.7 × 10²⁰ cm^?3 through heavily Br doping, resulting in simultaneously enhancing the electrical conductivities and Seebeck coefficients. Meanwhile, an extremely low thermal conductivity (≈0.6–0.4 W m^?1 K^?1 at 300–800 K) is found in BiSbSe₃. Both first‐principles calculations and elastic properties measurements show the strong anharmonicity and support the ultra‐low thermal conductivity of BiSbSe₃. Finally, a maximum dimensionless figure of merit ZT ～ 1.4 at 800 K is achieved in BiSb(Se_0.94Br_0.06)₃, which is comparable to the most n‐type Te‐free TE materials. The present results indicate that BiSbSe₃ is a new and a robust candidate for TE power generation in medium‐temperature range.     

Ti‐Doping to Reduce Conductivity in Bi0.85Nd0.15FeO3 Ceramics

In 2009, Karimi et al. reported that Bi_1‐xNd_xFeO₃ 0.15 ≤ x ≤ 0.25 exhibited a PbZrO₃ (PZ)‐like structure. These authors presented some preliminary electrical data for the PZ‐like composition but noted that the conductivity was too high to obtain radio‐frequency measurements representative of the intrinsic properties. In this study, Bi_0.85Nd_0.15Fe_1‐yTi_yO₃ (0 ≤ y ≤ 0.1) were investigated, in which Ti acted as a donor dopant on the B‐site. In contrast to the original study of Karimi et al., X‐ray diffraction (XRD) of Bi_0.85Nd_0.15FeO₃ revealed peaks which were attributed to a mixture of PZ‐like and rhombohedral structures. However, as the Ti (0 < y ≤ 0.05) concentration increased, the rhombohedral peaks disappeared and all intensities were attributed to the PZ‐like phase. For y = 0.1, broad XRD peaks indicated a significant decrease in effective diffracting volume. Electron diffraction confirmed that the PZ‐like phase was dominant for y ≤ 0.05, but for y = 0.1, an incommensurate structure was present, consistent with the broadened XRD peaks. The substitution of Fe³⁺ by Ti⁴⁺ decreased the dielectric loss at room temperature from >0.3 to <0.04 for all doped compositions, with a minimum (0.015) observed for y = 0.03. The decrease in dielectric loss was accompanied by a decrease in the room temperature bulk conductivity from ～1 mS cm^?1 to <1 μS cm^?1 and an increase in bulk activation energy from 0.29 to >1 eV. Plots of permittivity (?_r) versus temperature for 0.01 ≤ y ≤ 0.05 revealed a step rather than a peak in ?_r on heating at the same temperature determined for the antiferroelectric–paraelectric phase transition by differential scanning calorimetry. Finally, large electric fields were applied to all doped samples which resulted in a linear dependence of polarisation on the electric field similar to that obtained for PbZrO₃ ceramics under equivalent experimental conditions.     

A Direct Approach to Organic/Inorganic Semiconductor Hybrid Particles via Functionalized Polyfluorene Ligands

Controlled Suzuki–Miyaura coupling polymerization of 7′‐bromo‐9′,9′‐dioctyl‐fluoren‐2′‐yl‐4,4,5,5‐tetramethyl‐[1,3,2]dioxaborolane initiated by bromo(4‐tert‐butoxycarbonylamino‐phenyl)(tri‐tert‐butylphosphine)palladium ( 1 ) or bromo(4‐diethoxyphosphoryl‐phenyl)(tri‐tert‐butylphosphine)palladium ( 2 ) yields functionalized polyfluorenes (M_n = 4 × 10³ g mol^?1, M_w/M_n < 1.2) with a single amine or phosphonic acid, respectively, end‐group. High temperature synthesis of cadmium selenide quantum dots with these functionalized polyfluorenes as stabilizing ligands yields hybrid particles consisting of good quality (e.g. emission full width at half maximum of 30 nm; size distribution σ < 10%) inorganic nanocrystals with polyfluorene attached to the surface, as corroborated by transmission electron microscopy analysis and analytical ultracentrifugation. Sedimentation studies on particle dispersions show that a substantial portion (ca. half) of the phosphonic acid terminated polyfluorene ligands is bound to the inorganic nanocrystals, versus ca. 5% for the amino‐functionalized polyfluorene ligands. Single particle micro‐photoluminescence spectroscopy shows an efficient and complete energy transfer from the polyfluorene layer to the inorganic quantum dot.     

Structural defects and electrical conductivity in nanocrystalline SiC:H films doped with boron and grown by photostimulated chemical-vapor deposition

The paramagnetic DB defects and dark conductivity σ_d in films of nanocrystalline hydrogenated silicon doped with boron and carbon (nc-SiC:H) and grown by photostimulated chemical vapor deposition are studied. It is shown that an increase in the doping level leads to a phase transition from the crystalline structure to an amorphous structure. The electrical conductivity increases as the doping level increases and attains the value of σ_d = 5.5 × 10^?2 Ω^?1 cm^?1; however, the conductivity decreases once the phase transition has occurred. The concentration of DB defects decreases steadily as the doping level increases and varies from 10¹⁹ cm^?3 (in the crystalline structure) to 9×10¹⁷ cm^?3 (in the amorphous structure).     

Harnessing Selective Exsolution of Sn Metal to Enhance Electrical Conductivity in Oxygen-Deficient Perovskite Stannates

The versatile application of newly discovered oxide semiconductors calls for developing a simple process to generate conducting carriers. High-temperature reduction treatment leads to electrical conduction in perovskite stannate semiconductors, but carrier concentration is poorly controlled and inconsistently reported in BaSnO_3−δ films after the reduction process so far. Here, a new strategy to enhance the electrical conductivity of BaSnO_3−δ films is demonstrated by exploiting selective exsolution of Sn metals in the perovskite framework. Due to strong dependence of conductivity on initial Sn/Ba cation ratio in the reduced BaSnO_3−δ films, interestingly, only Sn-excess BaSnO_3−δ films show a dramatic increase of carrier concentration ( ∆ n_3D  = 5–7 × 10¹⁹ cm⁻³) after high-temperature reduction; exceptionally high electrical conductivity (σ  ≈  6000 S cm⁻¹) is achieved in reduced Sn-excess (La, Ba)SnO_3−δ films, which exceed full activation of La dopants in untreated (La, Ba)SnO₃. By multiple characterizations combined with theoretical calculation, it is disclosed that a small fraction of segregated β-Sn nanoparticles is likely to contribute the additional source of n_3D in the BaSnO_3−δ matrix as a result of spontaneous charge transfer from the segregated β-Sn metallic phase to BaSnO_3−δ. These original results propose a simple strategy to further increase electrical conductivity in perovskite oxide semiconductors by non-stoichiometry-driven metal exsolution.     

Temperature‐Resolved Local and Macroscopic Charge Carrier Transport in Thin P3HT Layers

Previous investigations of the field‐effect mobility in poly(3‐hexylthiophene) (P3HT) layers revealed a strong dependence on molecular weight (MW), which was shown to be closely related to layer morphology. Here, charge carrier mobilities of two P3HT MW fractions (medium‐MW: M_n = 7 200 g mol^?1; high‐MW: M_n = 27 000 g mol^?1) are probed as a function of temperature at a local and a macroscopic length scale, using pulse‐radiolysis time‐resolved microwave conductivity (PR‐TRMC) and organic field‐effect transistor measurements, respectively. In contrast to the macroscopic transport properties, the local intra‐grain mobility depends only weakly on MW (being in the order of 10^?2 cm² V^?1 s^?1) and being thermally activated below the melting temperature for both fractions. The striking differences of charge transport at both length scales are related to the heterogeneity of the layer morphology. The quantitative analysis of temperature‐dependent UV/Vis absorption spectra according to a model of F. C. Spano reveals that a substantial amount of disordered material is present in these P3HT layers. Moreover, the analysis predicts that aggregates in medium‐MW P3HT undergo a “pre‐melting” significantly below the actual melting temperature. The results suggest that macroscopic charge transport in samples of short‐chain P3HT is strongly inhibited by the presence of disordered domains, while in high‐MW P3HT the low‐mobility disordered zones are bridged via inter‐crystalline molecular connections.     

Imidazolium Polyesters: Structure–Property Relationships in Thermal Behavior,Ionic Conductivity,and Morphology

New bis(ω‐hydroxyalkyl)imidazolium and 1,2‐bis[N‐(ω‐hydroxyalkyl)imidazolium]ethane salts are synthesized and characterized; most of the salts are room temperature ionic liquids. These hydroxyl end‐functionalized ionic liquids are polymerized with diacid chlorides, yielding polyesters containing imidazolium cations embedded in the main chain. By X‐ray scattering, four polyesters are found to be semicrystalline at room temperature: mono‐imidazolium‐C₁₁‐sebacate‐C₆ ( 4e ), mono‐imidazolium‐C₁₁‐sebacate‐C₁₁ ( 4c ), bis(imidazolium)ethane‐C₆‐sebacate‐C₆ ( 5a ), and bis(imidazolium)ethane‐C₁₁‐sebacate‐C₁₁ ( 5c ), all with hexafluorophosphate counterions. The other imidazolium polyesters, including all those with bis(trifluoromethanesulfonyl)imide (TFSI^?) counterions, are amorphous at room temperature. Room temperature ionic conductivities of the mono‐imidazolium polyesters (4 × 10^?6 to 3 × 10^?5 S cm^?1) are higher than those of the corresponding bis‐imidazolium polyesters (4 × 10^?9 to 8 × 10^?6 S cm^?1), even though the bis‐imidazolium polyesters have higher ion concentrations. Counterions affect ionic conduction significantly; all polymers with TFSI^? counterions have higher ionic conductivities than the hexafluorophosphate analogs. Interestingly, the hexafluorophosphate polyester, 1,2‐bis(imidazolium)ethane‐C₁₁‐sebacate‐C₁₁ ( 5c ), displays almost 400‐fold higher room temperature ionic conductivity (1.6 × 10^?6 S cm^?1) than the 1,2‐bis(imidazolium)ethane‐C₆‐sebacate‐C₆ analog ( 5a , 4.3 × 10^?9 S cm^?1), attributable to the differences in the semicrystalline structure in 5c as compared to 5a . These results indicate that semicrystalline polymers may result in high ionic conductivity in a soft (low glass tranition temperature, T_g) amorphous phase and good mechanical properties of the crystalline phase.     

Glass‐Like Through‐Plane Thermal Conductivity Induced by Oxygen Vacancies in Nanoscale Epitaxial La0.5Sr0.5CoO3−δ

Ultrafast time‐domain thermoreflectance (TDTR) is utilized to extract the through‐plane thermal conductivity (Λ _LSCO) of epitaxial La_0.5Sr_0.5CoO_3?δ (LSCO) of varying thickness (<20 nm) on LaAlO₃ and SrTiO₃ substrates. These LSCO films possess ordered oxygen vacancies as the primary means of lattice mismatch accommodation with the substrate, which induces compressive/tensile strain and thus controls the orientation of the oxygen vacancy ordering (OVO). TDTR results demonstrate that the room‐temperature Λ _LSCO of LSCO on both substrates (1.7 W m^?1 K^?1) are nearly a factor of four lower than that of bulk single‐crystal LSCO (6.2 W m^?1 K^?1). Remarkably, this approaches the lower limit of amorphous oxides (e.g., 1.3 W m^?1 K^?1 for glass), with no dependence on the OVO orientation. Through theoretical simulations, origins of the glass‐like thermal conductivity of LSCO are revealed as a combined effect resulting from oxygen vacancies (the dominant factor), Sr substitution, size effects, and the weak electron/phonon coupling within the LSCO film. The absence of OVO dependence in the measured Λ _LSCO is rationalized by two main effects: (1) the nearly isotropic phononic thermal conductivity resulting from the imperfect OVO planes when δ is small; (2) the missing electronic contribution to Λ _LSCO along the through‐plane direction for these ultrathin LSCO films on insulating substrates.     

Engineering Thermal Conductivity for Balancing Between Reliability and Performance of Bulk Thermoelectric Generators

The nanostructuring approach has significantly contributed to the improving of thermoelectric figure‐of‐merit (ZT) by reducing lattice thermal conductivity. Even though it is an effective method to enhance ZT, the drastically lowered thermal conductivity in some cases can cause thermomechanical issues leading to decreased reliability of thermoelectric generators. Here, an engineering thermal conductivity (κ_eng) is defined as a minimum allowable thermal conductivity of a thermoelectric material in a module, and is evaluated to avoid thermomechanical failure and thermoelectric degradation of a device. Additionally, there is dilemma of determining thermoelectric leg length: a shorter leg is desired for higher W kg^?1, W cm^?3, and W The nanostructuring approach has significantly contributed to the improving of thermoelectric figure‐of‐merit (ZT) by reducing lattice thermal conductivity. Even though it is an effective method to enhance ZT, the drastically lowered thermal conductivity in some cases can cause thermomechanical issues leading to decreased reliability of thermoelectric generators. Here, an engineering thermal conductivity (κ_eng) is defined as a minimum allowable thermal conductivity of a thermoelectric material in a module, and is evaluated to avoid thermomechanical failure and thermoelectric degradation of a device. Additionally, there is dilemma of determining thermoelectric leg length: a shorter leg is desired for higher W kg^?1, W cm^?3, and W $^?1, but it raises the thermomechanical vulnerability issue. By considering a balance between the thermoelectric performance and thermomechanical reliability issues, it is discussed how to improve device reliability of thermoelectric generators and the engineering thermal conductivity of thermoelectric materials.     

Special features of conductivity mechanisms in heavily doped n-ZrNiSn intermetallic semiconductors

The effect of high concentrations of acceptor dopants (N _A = 10²⁰ cm^?3) on the electronic structure, Fermi level, electrical conductivity, Seebeck coefficient, and magnetic susceptibility of n-ZrNiSn intermetallic semiconductors is studied. The role of impurity bands produced by donors and acceptors in the conductivity of the heavily doped n-ZrNiSn compound is clarified. The transition from activated conductivity to metal conductivity under variations in the concentration of acceptor dopants is observed.     

Effects of Second Phase Yb5Sb3 on the Thermoelectric Properties of YbAl3

The compound YbAl₃ exhibits a very high power factor but also rather a large thermal conductivity, leading to a low figure of merit. The second phase Yb₅Sb₃ was introduced in the YbAl₃ matrix to reduce its thermal conductivity. The composites (YbAl₃)_1?x (Yb₅Sb₃) _x with x = 0, 0.01, 0.05, 0.10, and 0.20 were synthesized by high frequency induction melting, annealing treatment, and spark plasma sintering. The thermoelectric properties of the composites were evaluated. The composites are of n-type conduction. The pure YbAl₃ obtained in this work shows a high power factor of 11,500 μW m^?1 K^?2 but also a high thermal conductivity of 19.6 W m^?1 K^?1. However, the existence of Yb₅Sb₃ compound in the YbAl₃ matrix enhances the electrical resistivity and the absolute Seebeck coefficient of the composite, but significantly reduces its thermal conductivity in the temperature range considered, thereby enhancing the figure of merit. The highest ZT value of 0.23 may be obtained in the sample (YbAl₃)_0.95(Yb₅Sb₃)_0.05 at room temperature, which is apparently higher than that of pure YbAl₃.     

Electrical properties of Zinc-Tin diarsenide (ZnSnAs<Subscript>2</Subscript>) irradiated with H<Superscript>+</Superscript> ions

The results of studying the electrical properties and isochronous annealing of p-ZnSnAs₂ irradiated with H⁺ ions (energy E = 5 MeV, dose D = 2 × 10¹⁶ cm^?2) are reported. The limiting electrical characteristics of irradiated material (the Hall coefficient R _H (D)_lim ≈ ?4 × 10³ cm³ C^?1, conductivity σ (D)_lim ≈ 2.9 × 10^?2 Ω^?1 cm^?1, and the Fermi level position F _lim ≈ 0.58 eV above the valence-band top at 300 K) are determined. The energy position of the “neutral” point for the ZnSnAs₂ compound is calculated.     

Energy Spectra of the Local States in the Forbidden Gap of Monoclinic TlInS 2x Se 2(1−x) Crystals

Near IR properties of the mixed TlInS_2xSe_2(1?x) have been studied previously by the present authors. In this work the temperature and frequency dependence's of the conductivity and the current-voltage characteristics (in relatively weak electric field), have been investigated for monoclinic TlInS_2xSe_2(1?x) crystals, which are perspective materials for IR applications. From the temperature dependence's of conductivity in the direction perpendicular to c- axis the band gap E^g = 2.22 eV was determined for β--TlInS₂ crystals. The impurity centres were determined located at 0.43, 0.73 eV and 0.35, 0.48, 1.12 eV for the direction of current i//c and i ⊥ c, respectively. The concentration of the centres located at 0.48 and 1.12 eV were calculated to be N_A ? N_D = 4.8 · 10⁹ cm^?3 and 1.9 · 10¹¹ cm^?3, respectively. It was found that in the solid solutions TlInS_2xSe_2(1?x) for 0.3 ≤ x ≤ 1, the conductivity follows the dependence σ (v) = σ₀·υ^s in the temperature range between 100 to 600 K. In the temperature range of 80-400 K charge bounce plays an important role in the conductivity mechanism. Occurrence of the deep and low-levels impurity centres and a “tail” of the density of energy states in TlInS_2xSe_2(1?x) crystals make them perspective for practical applications: switching and memory effects, N-type current-voltage characteristics, induced conductivity etc.     

Nonohmic conductivity under transition from weak to strong localization in GaAs/InGaAs structures with a two-dimensional electron gas

Dependences of electrical conductivity σ on temperature and electric-field strength were studied in a wide range of conductivities (from σ ? e²/? to σ ? e²/?) in GaAs/InGaAs/GaAs structures with a two-dimensional electron gas. It is shown that one cannot reliably determine the mechanism of conductivity from the temperature dependence of ohmic conductivity. Studies of nonohmic conductivity make it possible to determine the range of values of low-temperature conductivity that correspond to the transition from the diffusion mechanism of conductivity to the hopping mechanism. It is shown that, in the structures under investigation, the conductivity is still controlled by diffusion as the degree of disorder increases even when the low-temperature conductivity is much lower than e²/?.     

A High‐Performance Li–B–H Electrolyte for All‐Solid‐State Li Batteries

Highly Li‐ion conductive Li₄(BH₄)₃I@SBA‐15 is synthesized by confining the LiI doped LiBH₄ into mesoporous silica SBA‐15. Uniform nanoconfinement of P6₃ mc phase Li₄(BH₄)₃I in SBA‐15 mesopores leads to a significantly enhanced conductivity of 2.5 × 10^?4 S cm^?1 with a Li‐ion transference number of 0.97 at 35 °C. The super Li‐ion mobility in the interface layer with a thickness of 1.2 nm between Li₄(BH₄)₃I and SBA‐15 is believed to be responsible for the fast Li‐ion conduction in Li₄(BH₄)₃I@SBA‐15. Additionally, Li₄(BH₄)₃I@SBA‐15 also exhibits a wide apparent electrochemical stability window (0 to 5 V vs Li/Li⁺) and a superior Li dendrite suppression capability (critical current density 2.6 mA cm^?2 at 55 °C) due to the formation of stable interphases. More importantly, Li₄(BH₄)₃I@SBA‐15‐based Li batteries using either high‐capacity sulfur cathode or high‐voltage oxide cathode show excellent electrochemical performances, making Li₄(BH₄)₃I@SBA‐15 a very attractive electrolyte for next‐generation all‐solid‐state Li batteries.     

High Thermoelectric Performance in Supersaturated Solid Solutions and Nanostructured n‐Type PbTe–GeTe

Sb‐doped and GeTe‐alloyed n‐type thermoelectric materials that show an excellent figure of merit ZT in the intermediate temperature range (400–800 K) are reported. The synergistic effect of favorable changes to the band structure resulting in high Seebeck coefficient and enhanced phonon scattering by point defects and nanoscale precipitates resulting in reduction of thermal conductivity are demonstrated. The samples can be tuned as single‐phase solid solution (SS) or two‐phase system with nanoscale precipitates (Nano) based on the annealing processes. The GeTe alloying results in band structure modification by widening the bandgap and increasing the density‐of‐states effective mass of PbTe, resulting in significantly enhanced Seebeck coefficients. The nanoscale precipitates can improve the power factor in the low temperature range and further reduce the lattice thermal conductivity (κ_lat). Specifically, the Seebeck coefficient of Pb_0.988Sb_0.012Te–13%GeTe–Nano approaches ?280 µV K^?1 at 673 K with a low κ_lat of 0.56 W m^?1 K^?1 at 573 K. Consequently, a peak ZT value of 1.38 is achieved at 623 K. Moreover, a high average ZT_avg value of ≈1.04 is obtained in the temperature range from 300 to 773 K for n‐type Pb_0.988Sb_0.012Te–13%GeTe–Nano.