A5058753589- Advanced Thermoelectric Materials and Devices
- Heusler alloys: electronic and magnetic properties
- 2D Materials and Applications
- Chalcogenide Semiconductor Thin Films
- Semiconductor materials and interfaces
- Superconductivity in MgB2 and Alloys
- Inorganic Chemistry and Materials
- Electronic and Structural Properties of Oxides
- Machine Learning in Materials Science
- Advancements in Semiconductor Devices and Circuit Design
- Thermal Expansion and Ionic Conductivity
- Perovskite Materials and Applications
- Surface and Thin Film Phenomena
- Silicon and Solar Cell Technologies
- Advanced Sensor and Energy Harvesting Materials
- Thermal properties of materials
- Innovative Energy Harvesting Technologies
- Topological Materials and Phenomena
- Quantum Dots Synthesis And Properties
- Electron and X-Ray Spectroscopy Techniques
- Energy Harvesting in Wireless Networks
- Semiconductor materials and devices
- MXene and MAX Phase Materials
- Magnetic and transport properties of perovskites and related materials
- Advanced Chemical Physics Studies
Northwestern University
2020-2025
The density of states electrons is a simple, yet highly-informative, summary the electronic structure material. Here, some remarkable features that are perceptible from concisely reviewed, notably analytical E vs. k dispersion relation near band edges, effective mass, Van Hove singularities, and dimensionality electrons, all which have strong influence on physical properties materials. We emphasize appropriate parameters in calculations necessary to obtain even sufficient-quality exhibiting...
Abstract Ambient energy harvesting has great potential to contribute sustainable development and address growing environmental challenges. Converting waste from energy-intensive processes systems (e.g. combustion engines furnaces) is crucial reducing their impact achieving net-zero emissions. Compact harvesters will also be key powering the exponentially smart devices ecosystem that part of Internet Things, thus enabling futuristic applications can improve our quality life homes, cities,...
A new strategy to trace the chemical bonding origins of band structure explains silicon's unusual low-symmetry conduction minimum.
An ultrahigh zT of 2.7 at 700 K is achieved in a (Ge 0.86 Sb 0.08 Bi 0.06 )Te single crystal. This outstanding performance attributed to one-dimensional-like electronic structure and the resulting strong electron–phonon interaction.
A modified HTP synthesis method and an automated histogram analysis technique are developed to screen the new stable ternary CTS compound Cu<sub>7</sub>Sn<sub>3</sub>S<sub>10</sub>.
PbTe is one of the highest-performing known thermoelectric materials. Much its promising performance can be attributed to high valley degeneracy due having a valence band minimum (VBM) and conduction maximum (CBM) at L-point in first Brillouin zone, which has 4-fold degeneracy, instead Γ, 1-fold degeneracy. The existence VBM L been explained by contribution Pb-s states that make up edge. However, dominance Te-p presence Pb-p near suggest orbitals may not as crucial previously thought....
Two conduction bands with very different effective masses are usually at the X point in half-Heusler Brillouin zone. Our orbital phase diagram provides feasible strategies to converge these two for thermoelectric enhancement.
Abstract Half‐Heusler compounds with semiconducting behavior have been developed as high‐performance thermoelectric materials for power generation. Many half‐Heusler also exhibit metallic without a bandgap and thus inferior performance. Here, taking MgNiSb an example, opening strategy is proposed by introducing the d–d orbital interactions, which enables of improvement The width can be engineered tuning strength interactions. conduction type carrier density modulated in Mg 1‐ x Ti NiSb...
SnTe is an attractive candidate for applications as a p-type thermoelectric semiconductor. The pristine compound exhibits poor performance at high temperatures because of its hole concentration, small band gap, and large energy difference between the light heavy bands (ΔE(L – Σ)). To overcome these problems, we investigate structure changes upon addition trivalent dopants based on tight-binding (TB) model density functional theory (DFT) calculations. We find that tuning relative on-site...
Abstract Half‐Heusler (hH) compounds are promising candidates for inexpensive, low‐toxicity thermoelectric materials. It is well known that engineering electronic bands with high valley degeneracy an effective approach enhancing the performance of materials, and there several routes achieving in hH systems. For instance, multiple locations first Brillouin zone where valence band maximum can be found (at Γ‐, L‐, or W‐point), two competing low‐lying conduction at X‐point, minimum located. By...
The tight-binding method provides insight into the orbital interactions that lead to exceptional thermoelectric performance of PbTe. Using this framework, we can predict strategies achieve enhanced in new alloys.
Valley degeneracy in materials with inverted bands can be increased by strengthening the band inversion. One method to tune inversion is controlling chemical interactions between cation and anion atomic orbitals.
Abstract The electronic structures of charged point defects influence electrical and optical properties semiconductors. Understanding the orbital interactions responsible for therefore promotes a chemical intuition defect‐driven mechanisms in In this tutorial, we discuss molecular theory‐based framework understanding defect‐induced states based on local between defect atoms surrounding site. By using Mg 2 Si as case study, show how both orbitals (i. e., wave functions) charge state(s) can be...
Density functional theory (DFT) is a powerful tool for predicting the electronic band structures of materials. However, it often difficult to intuit how major structure features$-$such as gap magnitude, location extrema, effective masses, etc.$-$arise from underlying crystal chemistry material. Band represented in reciprocal space, but arises orbital and bonding interactions between atoms real space. Here, we present conceptual computable framework extract chemical origins DFT-calculated...
The number of excess charge carriers generated by a point defect, defined the "charge state" is oftentimes an important quantity used to engineer electronic properties semiconductors. Here, we develop molecular orbital theory-based framework for interpreting state(s) which based on local chemical interactions between defect and atoms surrounding site. We demonstrate how can be applied native defects in Mg2Si, such as interstitials, vacancies, antisite defects, utilizing symmetry principles...
The electronic density of states (DOS) highlights fundamental properties materials that oftentimes dictate their properties, such as the band gap and Van Hove singularities. In this short note, we discuss how sharp features can be obscured by smearing methods (such Gaussian Fermi methods) when calculating DOS. While common approach to reach a "converged" material is increase discrete k-point mesh density, show DOS calculated appear converge but not correct Employing tetrahedron method for...
The number of excess charge carriers generated by a point defect, defined the "charge state" is oftentimes an important quantity used to engineer electronic properties semiconductors. Here, we develop molecular orbital theory-based framework for interpreting state(s) which based on local chemical interactions between defect and atoms surrounding site. We demonstrate how can be applied native defects in Mg2Si, such as interstitials, vacancies, antisite defects, utilizing symmetry principles...
Valley degeneracy is a key feature of the electronic structure that benefits thermoelectric performance material. Despite recent studies which claim high valley can be achieved with inverted bands, our survey rock-salt IV-VI compounds demonstrates mere band inversion an insufficient condition for degeneracy; rather, there critical degree to bands must induce multiple carrier pockets. The so-called “band parameter” chemically-tunable parameter, offering design route achieving in bands. We...
Semiconducting half-Heusler (HH, XYZ) phases are promising thermoelectric materials owing to their versatile electronic properties. Because the valence band of benefit from extrema at several high-symmetry points in Brillouin zone (BZ), it is possible engineer better p-type HH through convergence. However, studies n-type have been lagging behind since conduction minimum always same point (X) BZ, giving impression that there little opportunity for engineering. Here we study orbital diagram 69...
Valley degeneracy is a key feature of the electronic structure that benefits thermoelectric performance material. Despite recent studies which claim high valley can be achieved with inverted bands, our survey rock-salt IV-VI compounds demonstrates mere band inversion an insufficient condition for degeneracy; rather, there critical degree to bands must induce multiple carrier pockets. The so-called “band parameter” chemically-tunable parameter, offering design route achieving in bands. We...
Semiconducting half-Heusler (HH, XYZ) phases are promising thermoelectric materials owing to their versatile electronic properties. Because the valence band of benefit from extrema at several high-symmetry points in Brillouin zone (BZ), it is possible engineer better p-type HH through convergence. However, studies n-type have been lagging behind since conduction minimum always same point (X) BZ, giving impression that there little opportunity for engineering. Here we study orbital diagram 69...