Transverse Conductivity Research Articles

Electrical conductivity of hot relativistic plasma in a strong magnetic field

We employ first-principles quantum field theoretical methods to investigate the longitudinal and transverse electrical conductivities of a strongly magnetized hot quantum electrodynamics (QED) plasma at the leading order in coupling. The analysis employs the fermion damping rate in the Landau-level representation, calculated with full kinematics and exact amplitudes of one-to-two and two-to-one QED processes. In the relativistic regime, both conductivities exhibit an approximate scaling behavior described by σ∥,⊥=Tσ˜∥,⊥, where σ˜∥,⊥ are functions of the dimensionless ratio |eB|/T2 (with T denoting temperature and B magnetic field strength). We argue that the mechanisms for the transverse and longitudinal conductivities differ significantly, leading to a strong suppression of the former in comparison to the latter. Published by the American Physical Society 2024

Inelastic scattering effects on the inhomogeneous transverse conductivity of liquid metals and plasmas

Abstract On the basis of the quantum Wigner density operator formalism for multicomponent charged particle systems, the wavenumber (k)- and frequency (ω)- dependent transverse conductivity σ^T (k,ω) of simple liquid metals is presented for homogeneous (k = 0) and inhomogeneous (k≠0) electric fields separately. The theory takes into account correlated density fluctuations of electrons and ions, with their mutual inelastic scattering being described by the ionic dynamic structure factors. Since homogeneous and inhomogeneous fields perturb the diagonal and off-diagonal elements of the density matrix, respectively, the corresponding transport equations exhibit a dissimilarity in their collision terms. In both cases, approximate solutions to the transport equations yield a conductivity of generalized Drude form characterized by the k- and ω-dependent complex relaxation time. It is shown that the k→0 limit of the inhomogeneous conductivity, σ^T (k→0,ω), coincides with the homogeneous one in classical ion regime such that βℏω_i≪1, where β is the inverse temperature and ω_i is a characteristic frequency of ionic density fluctuation; this condition may be satisfied for metals well above melting. At lower temperatures, it is suggested that the (homogeneous) DC conductivity σ(0) can exceed the (inhomogeneous) optical conductivity extrapolated to zero frequency, σ^T (k→0,0). This trend is qualitatively consistent with earlier observations for liquid polyvalent metals.

Participation of epicardial connection in transverse conduction across the crista terminalis in patients with upper and lower loop reentry atrial tachycardias

Abstract Background The crista terminalis (CT) sometimes serves as a partial or complete conduction barrier, which is rate- and site-dependent. The basis, location and extent of the transverse conduction across the CT have been controversial. The pseudo-focal activation pattern indicates passive activation from the anatomically opposite chamber or structure. We previously reported cases of transverse CT conduction exhibiting a pseudo-focal activation pattern, indicating the CT conduction utilizing an epicardial connection (EC) in patients with upper loop reentry (ULR) atrial tachycardia (AT). Purpose This study aimed to investigate the prevalence and characteristics of transverse CT conduction using a high-resolution electroanatomical mapping system during CT-dependent AT and to compare between the ULR and lower loop reentry (LLR) ATs. Methods A total of 119 consecutive patients with macroreentrant AT were studied. The diagnosis of ULR/LLR AT was made based on endocardial activation mapping and entrainment pacing obtained from various sites around the superior/inferior vena cava. Transverse CT conduction utilizing an EC was defined as follows; (1) a centrifugal activation pattern with the earliest activation (EA) site >5 mm away from the CT, (2) later activation observed between the EA and the CT, and (3) the EA site exhibiting a pseudo-focal activation pattern (multiple breakthroughs or a small r wave on unipolar electrogram). Results Eighteen (15.1%) of the 119 patients were diagnosed with CT-dependent AT (15 men; median age, 71.5 years; AT cycle length, 265 ms; left atrial diameter, 42.5 mm; left ventricular ejection fraction, 49%). The 18 patients were divided into 2 groups: 9 patients with ULR and 9 with LLR AT. There were no significant differences in clinical characteristics (sex, history of cardiac surgery and organic heat disease) between ULR and LLR groups. Transverse CT conduction utilizing EC was more frequently observed in the ULR group than in the LLR group [77.8% (7/9) vs 22.2% (2/9), P=0.05]. In all patients with transverse CT conduction utilizing EC, scars extended along the CT. AT cycle length was significantly longer in the ULR group than in the LLR group (295 vs 235 ms, p=0.001). All ATs were successfully eliminated by radiofrequency ablation at the breakthrough sites and/or along the CT in ULR patients or by cavotricuspid isthmus ablation in LLR patients. Conclusions Half (9/18) of the patients with CT-dependent AT exhibited transverse CT conduction with a pseudo-focal activation pattern, suggesting the existence of an EC between the sinus venosus and the right auricle. The high prevalence of the pseudo-focal pattern in patients with the ULR compared to those with the LLR may provide insights into mechanisms.Figure1Figure2

Remodeling of adult rat heart subjected to pressure overload from the neonatal period is dependent on the sex

Abstract Background Congenital heart diseases (CHD) represents the most common birth defect. Despite progress in their treatment improving acute survival, there is a paucity of data concerning the long-term consequences of CHD in adults. Purpose Here, we investigate the remodeling in adult rat hearts subjected to pressure overload from the early postnatal period. Methods We used the neonatal abdominal aortic constriction (AAC) model to analyze morphological, functional (by echocardiography), and electrophysiological long-term outcomes. Given the known differences in cardiac pathologies between males (M) and females (F), we focused on the role of sex in cardiac remodeling. Results Our data showed that both sexes exhibited a similar left ventricular weight/body weight ratio at the age of 12 weeks, indicating comparable left ventricle (LV) enlargement as a response to AAC (increase by 103 ± 9 % in M AAC and 99 ± 10 % in F AAC vs. sham-operated animals). However, the right ventricular weight/body weight and lung/ body weight ratios, indicative of LV failing, differed significantly between sexes with better values in F AAC. The favorable cardiac remodeling in F AAC was corroborated by significantly smaller LV systolic and diastolic diameters, along with a lower amount of myocardial fibrosis. Using optical mapping, we revealed preserved longitudinal and transversal conduction velocities (CVL; CVT) in females (CVL 104 ± 8 vs. 109 ± 8 cm/s and CVT 66 ± 7 vs. 59 ± 6 cm/s in F AAC and F Sham, respectively). However, compared to M Sham, the conduction velocities in M AAC showed a significant decrease (CVL 80 ± 3 vs. 92 ± 3 cm/s and CVT 35 ± 2 vs. 54 ± 3 cm/s). Similarly, the amount of connexion 43 (Cx43) and its phosphorylated state (Cx43Ser368) was preserved in F AAC while exhibiting a decrease in M AAC compared to the sham-operated controls. Thus, electrophysiological findings implicate that while the adult M AAC underwent pro-arrhythmogenic remodeling due to the elevated workload, the adult F AAC preserved physiological conduction properties. Conclusion Our data showed different consequences of the increased pressure load exposed from early after birth to the adult M and F heart. These findings highlighted the involvement of both sexes in cardiac studies.

The influence of stochastic interface defects on the effective thermal conductivity of fiber-reinforced composites

In this paper, a novel microscopic modeling strategy is proposed to investigate the effective thermal conductivity of composites with consideration of stochastic interface defects. To this end, the subdomain boundary element method combined with asymptotic homogenization is proposed to effectively solve the thermal conduction problem. In order to accurately capture the heat flux on the boundary and the internal region in the representative volume element (RVE), a parameterized sub-cell is constructed to discretize the RVE. On this basis, the influence of stochastic interface defects on the thermal conductivity of composites is investigated by utilizing the Monte Carlo method. Specifically, the effect of the location, length, thickness, and area of the interface defects on the thermal conductivity is investigated. A proportional decrease in the transverse thermal conductivity coefficient is found for interface defect areas ranging from 1% to 10%.

Simulation on lightning erosion protection performance of CFRP laminates with metal cluster structure

The tufting technology has the advantages of high flexibility and high economy. Research has found that metal tufting structures can significantly improve the mechanical and electrical properties of carbon fiber composites, and have great prospects in engineering applications. In order to investigate the damage characteristics of carbon fiber CFRP laminates with metal tufted structures during lightning strikes and the influence of structural parameters on lightning protection effectiveness, an electric thermal coupling model of CFRP laminates with metal tufted structures was established. Comparing the simulation and experimental results under the same load condition, it was found that the two were consistent in terms of damage appearance, damage area, and damage propagation trend, proving the effectiveness of the model. The transverse heat transfer process and current conduction path of CFRP laminates with metal cluster structure were discussed. The research results indicate that the ablation surface area of CFRP laminates with metal tufted structures is reduced to 8.06% of the reference component. Wire spacing had an effect on the area and shape of the area of the high potential region, and the wire spacing had the greatest impact on the ablation area of lightning strikes.

Multiscale modeling and thermal conductivity evaluation of nano-reinforced composite materials with pore defect

The performance of resin-based composite materials often exhibits diversity due to the designability of various components. Thermal conductivity, an important thermal parameter of the composite, plays a significant role in thermal-chemical reactions, thermal stress analysis, temperature conduction, etc. However, it is relatively difficult to experimentally explore the thermal conduction mechanism of hybrid composite materials, mainly due to the relatively difficult control of various components. Therefore, this paper proposes a sequentially coupled cross-scale numerical method to characterize the thermal conductivity of nano-reinforced composite materials with pores by a multiscale periodic Representative Volume Element model generated by an improved Random Sequential Absorption algorithm. Firstly, periodic temperature boundary conditions are described, and the thermal conductivity performances of nano-reinforced matrix and composite with pores are investigated based on the finite element homogenization theory. Then, the proposed modes are validated and grid sensitivity analysis is conducted, indicating that the optimal grid sizes for the RVE models are 1.9 nm for the nano-reinforced matrix and 0.14 μm for the composite with pores based on a comprehensive comparison of four pore characterization methods, respectively. Furthermore, the study explored the effect of multiple parameters including nanoparticle content, pore content, and pore shape on thermal conductivity. Numerical findings reveal that the thermal conductivity of the nanocomposite matrix exhibits a linear increase with higher particle content. Specifically, compared to 0 % particle content, the thermal conductivity rises by 141.92 % at 12 % particle content. While the composite material's transverse thermal conductivity is sensitive to porosity content, it is less influenced by pore shape. The method proposed in this paper provides an effective approach for studying the thermal conduction of nano-reinforced composite materials with pores, and the research findings also offer theoretical guidance for process engineers.

Processing and properties of 3D woven SiC/SiC composites with hybrid matrix

3D woven SiC/SiC composites with Sylramic™-iBN SiC fibers have been fabricated by first partially infiltrating 3D woven fiber preforms with SiC by chemical vapor infiltration (CVI) and then by polymer infiltration and pyrolysis (PIP) of SiC-yielding polymer. The influence of fiber architecture on damage evolution and failure mechanisms during tensile loading, in-plane tensile properties, transverse thermal conductivity, and interlaminar tensile strength of the composites has been investigated. Wherever possible, the data are compared with those of 2D woven melt infiltrated (MI), CVI, and (CVI+PIP) hybrid SiC/SiC composites. The composites exhibit 300-hr creep durability at 1482 °C in air at stresses up to 138 MPa and show potential for elevated-temperature applications. Further improvements in composite properties are possible by optimizing composite constituents and fiber architecture.

An upscaling model for simulation of geothermal processes in stratified formations

In stratified porous media, non-uniform velocity between layers combined with thermal conduction across layers causes spreading of the thermal front: thermal Taylor dispersion. Conventional upscaling not accounting for this heterogeneity within simulation grid blocks underestimates thermal dispersion, leading to overestimation of thermal breakthrough time. We derive a model for effective longitudinal thermal diffusivity in the direction of flow, αeff, to represent the effective thermal dispersion in two-layer media. αeff, accounting for thermal Taylor dispersion, is much greater than the thermal diffusivity of the rock itself. We define a dimensionless number, NTC, a ratio of times for longitudinal convection to transverse conduction, as an indicator of transverse thermal equilibration of the system during cold- or hot-water injection. For NTC > 5, thermal dispersion in the two-layer system closely approximates a single layer with αeff. This suggests a two-layer medium satisfying NTC > 5 can be combined into a single layer with an effective longitudinal thermal diffusivity αeff. In application to a geothermal reservoir, one can apply the model to perform upscaling in stages, i.e. combining two layers satisfying the NTC criterion in each stage. The αeff model accounting for the fine-scale heterogeneity within simulation grid blocks would enhance the prediction accuracy of thermal breakthrough time and thus thermal lifetime.

Magneto-optical Hall response in generic Weyl semimetals

Weyl semimetals are predicted to host signature magneto-optical properties sourced by their peculiar Landau-level structure, including the chiral level. Analytical studies are often leaving out the Hall component of the conductivity due to its complicated nature, and even though the chiral anomaly requires Weyl nodes to come in charge-conjugate pairs, toy models hosting only one node are considered almost exclusively; numerical studies including several Weyl nodes are, on the other hand, often limited to high-field quantum limits or dc studies. Here, we present a twofold purpose study, where we (a) analytically derive a closed-form expression also for the Hall conductivity of a generic Weyl semimetal using linear response theory and (b) apply this general framework to evaluate the transverse conductivity components for Weyl systems with two nodes. We study how various model parameters, including the tilt, momentum separation, and energy location of the nodes, as well as the chemical potential, affect the magneto-optical conductivity, and complement these studies by deriving an analytical expression for the dc Hall conductivity, which is also evaluated in various systems. Including a chiral pair of nodes results in two important differences compared to earlier studies: the contribution from the chiral level is equal in size but opposite at the two nodes, making the net contribution disappear, and the energy scales at which intraband transitions occur is smeared out and approaches that of interband transitions, strengthening the hypothesis that intraband transitions mask signature optical features in materials. This general formalism can be applied to a large family of generic Weyl semimetals, and comprise an important piece towards unravelling the source of the mismatch between theoretical predictions and experimental observations in candidate materials. Published by the American Physical Society 2024

Micromechanical modeling of thermal conductivities of unidirectional carbon fiber/epoxy composites containing carbon nanotube/graphene hybrids

This article deals with the micromechanical modeling of thermal conductivities of the unidirectional carbon fiber (CF)-reinforced composites with carbon nanotube (CNT)/graphene nanoplatelet (GNP)-enriched epoxy matrix. The thermal conductivity of epoxy-based nanocompounds enriched through the incorporation of CNT/GNP hybrids is estimated within the framework of micromechanics. The significant contribution of several microstructures, including the volume fraction, dimension, and straightness of nanofillers, thermal resistance at the interface of the nanofillers and epoxy matrix, and the percolation effect on the nanocomposite thermal conductivity is considered. Furthermore, the method of cells (MOC) is used to anticipate the axial and transverse thermal conductances of unidirectional composites featuring CFs integrated into the CNT/GNP-enriched polymer nanocomposite matrix. The results reveal that incorporating a combination of GNTs and CNTs into the polymer matrix significantly increases the transverse thermal conduction of the multiphase compound. Several factors contribute to improved thermal conductance of the transverse direction in CF/CNT/GNP composites: (i) higher nanofiller concentration, (ii) presence of straight nanofillers, and (iii) use of larger nanofillers. The predictions of micromechanical modeling give good agreement with available experiments. This study compares the transverse and axial thermal conductivity of unidirectional compounds predicted by MOC method with results obtained using the finite element method.

Thermodynamic performance and flow structures analysis of supercritical CO2 applied in a regenerative cooling channel mounted with mini-ribs

Supercritical CO2 (SCO2) is regarded as a promising supplementary coolant for traditional regenerative cooling at extremely high flight speed (Ma ≥8) due to its superior heat and mass transfer capability. Using sCO2 as the coolant, mini-ribs is introduced to the rectangular regenerative cooling channel to solve the difficulties in transferring enough heat from near walls to core mainstream at a heat flux of 5 MW/m2 in this paper. With the thermophysical properties near the supercritical point interpolated in the solver, flow structures and heat transfer performance in the cooling channels are obtained using a validated k-ω SST turbulence model. Effects of pitch ratios, channel materials and acceleration and buoyancy effects are also investigated in terms of the local bulk heat transfer coefficients, Fanning friction factors and entropy generation numbers by heat transfer and fluid flow. Overall, the existing of mini-ribs improves the heat transfer coefficient and reduces the entropy number by heat transfer at the cost of the increased fluid friction and the corresponding entropy number. Compared with the smooth channel, the overall enhanced factor can reach 1.73 with an overall thermal performance factor of 1.43 and the maximum wall temperature decreases by 27.57 % in the case of P/e = 10. When the solid channel material has higher thermal conductivity, it leads to a more uniform temperature distribution and lower entropy generation number by heat transfer with the enhanced transverse heat conduction within solid walls which also leads large heat transfer coefficients. Larger accelerations result in stronger heat transfer and larger fluid friction by strengthening the buoyancy effect which is more obvious when the state approach the critical point. This work provides a good reference for the application of supercritical CO2 in a regenerative cooling channel of scramjet engine at extremely high heat flux.

Effect of shear flow on the transverse thermal conductivity of polymer melts.

The effect of shear flows on the thermal conductivity of polymer melts is investigated using a reversed nonequilibrium molecular-dynamics (RNEMD) method. We extended the original RNEMD method to simultaneously produce spatial gradients of temperature and flow velocity in a single direction. This method enables accurate measurement of the thermal conductivity in the direction transverse to shear flow. The Weissenberg number defined with the shear rate and the relaxation time of the polymer conformation can uniformly differentiate the occurrence of shear rate dependence of the thermal conductivity across different chain lengths. The stress-thermal rule (STR) (i.e., the linear relationship between anisotropic parts of the stress tensor and the thermal conductivity tensor) holds for entangled polymer melts even under shear flows but not for unentangled polymer melts. Furthermore, once entanglements form in polymer chains, the stress-thermal coefficient in the STR remains independent of the polymer chain length. These observations align with the theoretical foundation of the STR, which focuses on energy transmission along the network structure of entangled polymer chains [B. van den Brule, Rheol. Acta 28, 257 (1989)0035-451110.1007/BF01329335]. However, under driven shear flows, the stress-thermal coefficient is notably smaller than that measured in the literature for a quasiquiescent state without external forces. Although the mechanism of the STR in shear flows has yet to be fully elucidated, our study confirmed the validity of the STR in shear flows. This allows us to use the STR as a constitutive equationfor computational thermofluid dynamics of polymer melts, thus having broad engineering applications.

An overview of conjugate heat transfer augmentation methods for thermal management and recent advancements in microchannel heat sink overall performance

Recent technological advancement creates high-dense circuits development which creates colossal cooling demand requirements. In the future, advanced technology and scientific applications need to balance heat fluxes beyond limitation that catalyse the research opportunities further to achieve cooling requirements. Conventional cooling equipment is inappropriate for extracting heat from microchips within the minimal surface area. Microchannel technology appeared as a next-generation heat exchanger for the given heat duty. In the classical case of accounting, micro-heat exchangers both axial and transverse wall conduction effects is usually neglected. However, from the year 2005 onwards, researchers identified conduction dominance at fluid velocity is zero zones at the interface, which created balance between conduction–convection currents, finally included axial wall/heat conduction effects to a general model. This present study made a comparative evaluation fluid flow, heat transfer characteristics, thermal performance (TP) based on geometrical parameters, substrate materials and discusses previous issues, and current issues-based future research directions. Till today, based on applications of microchannels in thermal management, several experimental and numerical investigations have been reported for further improvement in TP. However, many researchers are still trying to accomplish things over a long period. Therefore, an overview of previous studies is furnished in the present study to assist researchers in this area much useful for further improvement.

Large transverse thermoelectric effect induced by the mixed-dimensionality of Fermi surfaces

Transverse thermoelectric effect, the conversion of longitudinal heat current into transverse electric current, or vice versa, offers a promising energy harvesting technology. Materials with axis-dependent conduction polarity, known as p × n-type conductors or goniopolar materials, are potential candidate, because the non-zero transverse elements of thermopower tensor appear under rotational operation, though the availability is highly limited. Here, we report that a ternary metal LaPt2B with unique crystal structure exhibits axis-dependent thermopower polarity, which is driven by mixed-dimensional Fermi surfaces consisting of quasi-one-dimensional hole sheet with out-of-plane velocity and quasi-two-dimensional electron sheets with in-plane velocity. The ideal mixed-dimensional conductor LaPt2B exhibits an extremely large transverse Peltier conductivity up to ∣αyx∣ = 130 A K−1 m−1, and its transverse thermoelectric performance surpasses those of topological magnets utilizing the anomalous Nernst effect. These results thus manifest the mixed-dimensionality as a key property for efficient transverse thermoelectric conversion.

Effective Manipulation of a Colossal Second-Order Transverse Response in an Electric-Field-Tunable Graphene Moiré System.

The second-order nonlinear transport illuminates a frequency-doubling response emerging in quantum materials with a broken inversion symmetry. The two principal driving mechanisms, the Berry curvature dipole and the skew scattering, reflect various information including ground-state symmetries, band dispersions, and topology of electronic wave functions. However, effective manipulation of them in a single system has been lacking, hindering the pursuit of strong responses. Here, we report on the effective manipulation of the two mechanisms in a single graphene moiré superlattice, AB-BA stacked twisted double bilayer graphene. Most saliently, by virtue of the high tunability of moiré band structures and scattering rates, a record-high second-order transverse conductivity ∼ 510 μm S V-1 is observed, which is orders of magnitude higher than any reported values in the literature. Our findings establish the potential of electrically tunable graphene moiré systems for nonlinear transport manipulations and applications.

Multifunctional properties of carbon nanotube yarn/aerogel laminate composites

This work explores the multifunctional performance of scalable carbon nanotube (CNT) yarn laminate composites. Tensile, thermal, electrical, and electromagnetic interference (EMI) shielding properties are compared to state-of-the-art unidirectional IM7/5250-4 carbon fiber composite (CFRP). CNT laminates achieved a specific tensile modulus of 249.7 ± 22.3 GPa/(g/cm3), which is over double the specific modulus of the CFRP, while maintaining a specific tensile strength of 1.88 ± 0.17 GPa/(g/cm3) which is comparable to the CFRP. CNT yarn laminates demonstrated superior thermal transport properties, with in-plane thermal conductivity of 75.78 ± 14.3 W/mK, over 13 times higher than the CFRP. CNT yarn laminates were also superior in electrical conductivity, achieving a longitudinal conductivity of 5359 ± 417 S/cm and transverse conductivity of 36.87 ± 2.55 S/cm. This translated to superior EMI shielding properties, achieving over 100 dB in the X-band, which is nearly double that of the CFRP. Incorporating CNT aerogel interwoven between CNT yarns reduced the large property variance observed in the measurements, demonstrating a multifunctional material with tensile, thermal, electrical, and EMI properties superior to the CFRP, while potentially mitigating the scalability challenges inherent to CNT nanomaterials.

Cryogenic thermal conductivity of carbon fiber reinforced polymer composite laminates

Carbon fiber reinforced polymer (CFRP) composites with excellent mechanical properties and low thermal conductivity are promising materials for cryogenic facility support structures. However, the temperature dependence and stacking sequence dependence of the laminates’ thermal conductivities challenge their thermo-mechanical design. Previous work dealing with the cryogenic thermal conductivity of laminates was relatively inadequate, and the effect of stacking sequence has not been sufficiently clarified. Herein, the cryogenic thermal conductivity of CFRP composite was investigated, and a theoretical model for the out-of-plane thermal conductivity of laminate was developed. To this end, the thermal conductivities of epoxy resin and laminates were measured at temperatures from 20 K to 293 K. The cryogenic thermal conductivity of carbon fiber was then extrapolated. Subsequently, a theoretical model was developed based on the thermal-electrical analogy method to evaluate the effect of stacking sequence. The obtained model was then validated by numerical analysis and experimental work. Lastly, the effects of lay-up angles and component properties on out-of-plane conductivity were examined. The test results suggested longitudinal thermal conductivity of composites exhibiting significant temperature dependence, with a decreasing trend recorded from 6.317 Wm−1K−1 to 0.355 Wm−1K−1 and transverse thermal conductivity decline from 0.626 Wm−1K−1 to 0.156 Wm−1K−1. The theoretical analysis indicated that the stacking sequence could reduce the out-of-face thermal conductivity by up to approximately 6.5 %, while the lay-up angle did not show any influence. In sum, novel insights into the cryogenic thermal conductivity of CFRP composites were provided, with guidance for the design and analysis of CFRP composites in cryogenic applications.

Визначення величини енергетичної невпорядкованості в аморфних оксидних напівпровідниках

The amorphous material films are resistant to high-energy irradiation. Therefore, devices built using the properties of these materials can work in conditions of increased radiation much longer than devices using the properties of crystals. An important characteristic of these materials is their degree of disorder. To determine this characteristic, a model of random fluctuations of the local edge of the conduction band is considered for the theoretical study of magnetoconductivity in amorphous oxide semiconductors. The effective medium approximation is used. An approach to determining the amount of energy disorder based on experimental measurement of changes in longitudinal and transverse electrical conductivity in a magnetic field is proposed.

Hierarchical Transparent Back Contacts for Bifacial CdTe PV.

A hierarchical transparent back contact leveraging an AlGaOx passivating layer, Ti3C2Tx MXene with a high work function, and a transparent cracked film lithography (CFL) templated nanogrid is demonstrated on copper-free cadmium telluride (CdTe) devices. AlGaOx improves device open-circuit voltage but reduces the fill factor when using a CFL-templated metal contact. Including a Ti3C2Tx interlayer improves the fill factor, lowers detrimental Schottky barriers, and enables metallization with CFL by providing transverse conduction into the nanogrid. The bifacial performance of an AlGaOx/Ti3C2Tx/CFL gold contact is evaluated, reaching 19.5% frontside efficiency and 2.8% backside efficiency under 1-sun illumination for a copper-free, group-V doped CdTe device. Under dual illumination, device power generation reached 200 W/m2 with 0.1 sun backside illumination.