Electronic Energy Levels Research Articles

Practical use of Seebeck and Pelter effects (Review)

The subject of research is industrial and household equipment and devices, the principle of operation of which is based on such thermoelectric phenomena as the Seebeck and Peltier effects. The purpose of the research is a critical analysis of the fields of practical application of the Peltier and Seebeck effects, as well as the constructive and technological design of the processes in which the specified effects are implemented to ensure a certain thermal regime, as well as the generation of electrical energy from waste heat. One of the main problems of today is global warming, environmental pollution and the increase in the cost of electricity. These problems can be partially solved with the help of thermoelectric phenomena, that is, physical phenomena caused by the relationship between electric current and heat flows in substances and contacts between them, which primarily include the Peltier and Seebeck effects. The indisputable advantages of thermoelectric means are their environmental safety, quiet operation and long service life. Seebeck and Peltier effects are used in chemical technology and related industries, renewable energy, construction, machine and instrument engineering, aerospace and military engineering, microelectronics, computer technology, medicine, personal hygiene devices, household appliances, and transportation. However, the low efficiency and the high cost of materials prevent the wide spread of thermoelectric technology. Wider application of thermoelectric technologies can be expected in case of development of new conductive materials with different energy levels of electrons in the conduction zone, as well as optimization of the geometry and structure of thermoelectric devices. Recently, intensive research has also been carried out on the so-called ionic Seebeck effect, which opens up new perspectives in thermoelectric phenomena, as well as the use of "magnetic thermoelectrics", or the spin Seebeck effect. This review can be useful to creators of new equipment and technology, because the fund of technical effects is widely used during the creation of innovative samples, which is an integral part of the information fund of inventors and helps them create simple, effective and bright solutions to technical problems.

Quantum-chemical modeling of dispersed systems with the yttrium aluminum garnet base

Laser material Y3Al5O12 (YAG), originally known in the form of a single-crystal, has been distributed and widely commercialized in the form of optical ceramics. The desire to expand the functionality of materials made of nanocrystals due to the size effect actualizes the study of the influence of their structure on the optical (vibrational and electronic) and other properties of new promising materials with the YAG base including glass ceramics. In this work, models of crystalline alumina-iodine garnet fragments have been calculated by DFT/uPBEPBE/SDD, DFT/uPBEPBE/lanl2DZ, and DFT/uB3PW91/SDD methods. The IR spectra were calculated by DFT/uPBEPBE/lanl2DZ method and the absorption bands of the calculated wave numbers were correlated with the measured ones. The electronic absorption spectrum and energy levels were calculated by the DFT/RB3PW91/SDD method.

Bidentate Lewis Base Ligand-Mediated Surface Stabilization and Modulation of the Electronic Structure of CsPbBr3 Perovskite Nanocrystals.

The desorption of conventional ligands from the surface of halide perovskite nanocrystals (NCs) often causes their structural instability and deterioration of the optoelectronic properties. To address this challenge, we present an approach of using a bidentate Lewis base ligand, namely, 1,4-bis(diphenylphosphino)butane (DBPP), for the synthesis of CsPbBr3 NCs. The phosphine group of DBPP has a strong interaction with the PbBr2 precursor, forming a highly crystalline intermediate complex during the reaction. In the presence of oleic acid, the uncoordinated phosphine group of DBPP is converted into the phosphonium cation, which strongly binds to the surface bromide of the formed CsPbBr3 NCs through hydrogen bonding. Density functional theory calculations suggest that DBPP can strongly bind to the undercoordinated lead and surface bromide ions of CsPbBr3 NCs through its unprotonated and protonated phosphine groups, respectively. The robust binding of DBPP to the surface of perovskite NCs helps to preserve their structural integrity under various environmental stresses. Moreover, the electron density and energy levels are regulated in DBPP-capped CsPbBr3 NCs by the donation of electrons from the ligands to the NCs, resulting in their improved photocatalytic CO2 reduction performance. Our study highlights the potential of using bidentate ligands to stabilize the surface of perovskite NCs and modulate their optical and electronic properties.

Internal Doping and Surface Coating: Mn/La-HCF @ Fe-HCF Composites as High-Performance Cathode Materials for Sodium-Ion Batteries

Manganese-based Prussian blue analogue (Mn-HCF) has outstanding advantages such as a high discharge platform, high discharge capacity and high energy density compared with other PB and PBAs, which is a very valuable cathode material for sodium-ion batteries. However, the rapid decrease in capacity in the cycle process by the Jahn–Teller effect caused by [Formula: see text] is the main obstacle to the commercialization of Mn-HCF. In this work, Mn/La-HCF @ Fe-HCF was synthesized by doping La element into the Mn-HCF phase to suppress the Jahn–Teller effect of Mn ions and coating the Fe-HCF phase outside to protect the Mn-HCF phase from electrolyte corrosion. Benefiting from the inhibition of the Jahn–Teller effect of [Formula: see text] by the abundant electronic energy level structure of La element and the protection of Fe-HCF phase relative to Mn-HCF phase, the initial discharge capacity of Mn/La-HCF @ Fe-HCF can reach 135.6 mAh [Formula: see text] at current density of 0.1 C, and it still has a high discharge capacity of 112.2[Formula: see text]mAh [Formula: see text] at current density of 5 C. After 300 cycles at a current density of 2 C, the reversible capacity of 117.6[Formula: see text]mAh [Formula: see text] is maintained (capacity retention rate is 86.1%). The results show that this method of internal doping and outsourcing can greatly improve the electrochemical performance of Mn-HCF, and provide feasible ideas for the commercialization of Mn-HCF.

Spectroscopy and crystal-field analysis of low-symmetry Er[formula omitted] centres in K[formula omitted]YF[formula omitted] microparticles

K2YF5 crystals doped with lanthanide ions have a variety of possible optical applications. Owing to the low symmetry of the system, the crystal structure cannot be unambiguously determined by x-ray diffraction. However, electron-paramagnetic resonance studies have demonstrated that lanthanide ions substitute for yttrium in sites of Cs local symmetry. In this work, we use high-resolution absorption and laser spectroscopy to determine electronic energy levels for Er3+ ions in K2YF5 microparticles. A total of 39 crystal-field energy levels, distributed among 7 multiplets of the Er3+ ion, have been assigned. This optical data is used for crystal-field modelling of the electronic structure of Er3+ in K2YF5. Our model is fitted not only to the electronic energy levels, but also to the ground-state g-tensor. This magnetic-splitting data defines the axis system of the calculation, avoiding ambiguities associated with low-symmetry crystal-field fits.

Strain induced crystal lattice softening and improved thermoelectric performance of hydrogenated silicene for energy harvesting applications

In recent years, Silicene has attracted great interest in various fields but does not fit well in the field of thermoelectrics due to the absence of electronic band gap. Nevertheless, hydrogenation of silicene (SiH) delocalize the free electrons and induces gap widening (2.19 eV), but its thermoelectric performance is still limited due to the larger band gap. Thermoelectric performance can be effectively improved using strain engineering, which allows modulation of crystal as well as electronic energy levels of a material. We studied the effect of biaxial tensile strain on structure, stability and thermoelectric properties of SiH monolayer. Taking clue regarding the stability from phonon dispersion, tensile strain upto 14% is incorporated and results are discussed. The distortion of crystal structure with strain manipulates the characteristics of electronic band structure such that there is an indirect to direct band gap transition along with decrease in band gap, effective mass and relaxation time of carriers. As a result, the Seebeck coefficient falls and attains minimum value at 14% strain while electrical conductivity and electronic thermal conductivity shows increasing trend and maximize at 14% strain. Another crucial consequence of strain is that tensile strain led to a considerable decrease in lattice thermal conductivity. At a strain of 14%, the lattice thermal conductivity at 700 K (0.28) decreased by approximately 43% compared to its unstrained counterpart (0.49 K), which is highly beneficial for achieving high ZT. To assess the efficiency of thermoelectric conversion, the ZT is computed, revealing an increase from 1.66 in the unstrained state to 2.83 at a strain of 14% and a temperature of 700 K. The calculations unveil a nearly twofold increase in ZT with the implementation of strain engineering, underscoring its effectiveness in augmenting the efficiency of thermoelectric devices.

N-Type Conjugated Polymers Based on Double B←N Bridged Bipyridine Unit.

ConspectusBoth p-type conjugated polymers and n-type conjugated polymers are required for organic optoelectronic devices, such as organic solar cells (OSCs), organic field-effect transistors (OFETs), organic thermoelectrics (OTEs), etc. The development of n-type conjugated polymers lags far behind that of the p-type counterparts in view of material diversity and optoelectronic device performance. This is mainly due to the lack of strong electron-withdrawing building blocks, which are always based on the imide unit. Double boron-nitrogen coordination bond (B←N) bridged bipyridine (BNBP), which was first developed in 2016, is an alternative kind of electron-withdrawing building block based on a B←N unit. BNBP itself possesses a planar and fixed configuration, low-lying electronic energy levels, strong fluorescence, and facile functionalization. A family of BNBP-based conjugated polymers has been developed. They show excellent and tunable optoelectronic properties, such as high electron mobility, low-lying and tunable lowest unoccupied molecular orbital (LUMO) energy level (ELUMO), medium bandgap, narrow absorption spectra in the visible range, high fluorescence quantum efficiency, etc. With rational molecular design of BNBP-based conjugated polymers, they have been widely used in organic optoelectronic devices with high performance, including OSCs, OFETs, and OTEs, indoor photovoltaics (IPVs), organic light-emitting diodes (OLEDs), organic photodetectors (OPDs), etc. Therefore, BNBP-based conjugated polymers have become an important class of optoelectronic materials. In this Account, we summarize the research progress on BNBP-based conjugated polymers.At first, we discuss BNBP itself, including its molecular design, synthesis, chemistry, and optoelectronic properties. Then we introduce the optoelectronic properties of BNBP-based conjugated polymers, including their light absorption property, fluorescence, electron mobility, and frontier electronic energy levels. We have systematically elucidated the relationship between the chemical structures, optoelectronic properties, and optoelectronic device performance of BNBP-based n-type conjugated polymers. The unique property of BNBP-based conjugated polymers is the high electron mobility in the amorphous state. Other noteworthy properties of these polymers are the medium bandgap and absorption spectra in the visible range. Next, we discuss the applications of BNBP-based conjugated polymers in OSCs, IPVs, OFETs, OTEs, OPDs, and OLEDs. The excellent optoelectronic device performance is noteworthy, such as power conversion efficiency (PCE) of 10% in OSCs, PCE of 26% in IPVs, electron mobility of 0.3 cm2 V-1 s-1 in OFETs, power factor of 25 μW m-1 K-2 in OTEs, specific detectivity of 1.79 × 1013 cm Hz1/2 W-1 in OPDs. Finally, we propose that great attention should be paid to the deep understanding of the electronic structures of BNBP itself and BNBP-based conjugated polymers as well as the new applications of BNBP-based conjugated polymers.

In Situ Clustering of Copper Nanoparticles in Mesoporous Cerium-Based Metal−Organic Frameworks for Efficient Electrocatalytic Nitrate Reduction to Ammonia

Owing to their tunable intra-framework functionalities as well as their exceptional chemical stability in water, cerium(IV)-based metal–organic frameworks (Ce-MOFs) have been utilized in a range of applications in aqueous solutions. By performing post-synthetic modifications (PSM), the high-density and spatially separated active units for the targeted reactions can be introduced within the entire framework structure, which makes Ce-MOFs particularly appealing for catalytic applications. Despite the low electrical conductivities of most MOFs hinder their direct use for electrochemical applications, electrons can be transported in the intrinsically insulating Ce-MOFs by node-to-node redox hopping during the electrochemical processes. We thus reasoned that chemically robust Ce-MOFs incorporated with spatially separated electrochemically active moieties should be intriguing materials for electrocatalytic systems. Nevertheless, the inherent microporous nature of most Ce-MOFs severely hinders the mass transfer and restricts the accessibility of reactants, which results in not only the limited utilization of active units but also poor catalytic activity. Recently, porosity engineering of MOFs has been regarded as a promising strategy to solve the issue. By selecting suitable polymeric surfactants as soft templates to guide the growth of MOF crystals, the morphology and ordered mesoporous arrays of MOFs could be facilely regulated. It is believed that the design of ordered mesoporous Ce-MOFs can improve the diffusion of guest molecules and enhance the electrocatalytic performances.Among various electrocatalytic reactions, the electrochemical reduction of nitrate (NO3 -) to ammonia (NH3) is particularly of interest. Nevertheless, the competitive hydrogen evolution reaction (HER) suppresses the Faradaic efficiency and ammonia yield. With the electronic energy level matching to the molecular orbital of nitrate, copper is regarded as a potential candidate that can rapidly adsorb nitrate at the catalytic sites and efficiently reduce nitrate. While the low porosity and limited surface-to-volume ratio result in the low metal utilization of bulk copper-based materials. By serving a Ce-MOF as a porous platform, copper ions can be decorated on the hexa-cerium nodes, and spatially separated Cu particles within nanopores of the Ce-MOF can be further obtained after electrochemical treatment. We thus reasoned that the use of chemically robust and mesoporous Ce-MOFs for the in-situ formation of Cu nanoparticles would be a promising strategy to facilitate the mass transfer of nitrate for the electrochemical ammonia production.In this study, a pluronic poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide) (PEO−PPO−PEO) surfactant was employed as a soft template for the formation of Ce-MOF crystals with ordered mesopores. The immobilization of copper ions on hexa-cerium nodes was further conducted by a solvothermal deposition in MOFs (SIM) method. Thereafter, in situ construction of Cu nanoparticles confined within the Ce-MOF skeleton (denoted as Cu@mesoMOF) was performed by the electroreduction method. The electrocatalytic performance for nitrate reduction to ammonia was investigated in 0.5 M Na2SO4 with 10 mM NaNO3, and chronoamperometric techniques were used to evaluate the activity. The catalyst loading of modified electrodes and the applied potential for nitrate reduction were first optimized. As a comparison, modified electrodes with Cu nanoparticles confined within the Ce-MOF without mesopores (Cu@MOF) were also performed. By providing the ordered mesopores as channels for mass transfer, the diffusion of nitrate from the external solution to the internal catalytic sites can be facilitated, and the experimental results here demonstrate that the Cu@mesoMOF thin film can achieve a higher Faradaic efficiency and better selectivity. Furthermore, a 1.8-fold ammonia production rate can be obtained for Cu@mesoMOF thin film compared to the Cu@MOF thin film, demonstrating the electrocatalytic activity is deeply influenced by the diffusion of reactants. Findings here shed light on the use of mesoporous MOFs for facilitating the mass transfer and suggest the rational design of mesoporous property can be a promising strategy to enhance the activity of MOF-based catalysts for electrocatalysis. Figure 1

Stress-Induced Modification for Interlayers in Lithium Metal Batteries

As solid-state electrolytes (SSE) gain attention in the academic and industrial space, thin film interlayers are increasingly used to enhance wettability and lower interfacial resistance. Gold films, or interlayers, are frequently sputtered on ceramic electrolytes to improve their contact bonding with both anodic and cathodic layers. To-date, adherence between the SSE and current collector without cracks or delamination has been considered sufficient to qualify a “good” interlayer deposition. It is well known in the surface science community, however, that thin films can sustain high levels of residual stress, depending on dose-momentum of the depositing species.For the first time, this work demonstrates the effects of interlayer residual stress on first and subsequent charge-discharge cycles and formulates a theory identifying the governing physical mechanism. We fabricate Au-Cu electrodes imbued with residual stress (-50 to 160 MPa) and cycle electrodeposited lithium on and off the surface to demonstrate unique morphological, electrochemical, and performance characteristics. Scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) measurements show that tensile interlayers result in larger, more irregularly shaped lithium structures that have high irreversibility, while compressive interlayers result in small, densely packed lithium structures with minimal solid electrolyte interface (SEI) formation (Figure 1a-d).We characterize the Au-Cu surface using SEM, nanoindentation, optical spectroscopy (UV-Vis-NIR), and ultraviolet photoelectron spectroscopy (UPS) to relate the physical properties of the interlayer to the electrochemical behavior. The test results show that film stress causes the equilibrium electron energy levels to shift. As the surface becomes more tensile, the contact energy decreases, the color reddens, and the work function increases (Figure 1e-g). This evidences a change in the electronic configuration, leading to distinct thermodynamic behavior in lithium structures. This work demonstrates the high sensitivity of the electrochemical environment to even minor changes in the initial condition of interlayer state and presents a guide for consistent fabrication parameters that maximize the potential interlayer benefits offered by residual stress control. Figure 1

Novel hole transport materials of pyrogallol-sulfonamide hybrid: synthesis, optical, electrochemical properties and molecular modelling for perovskite solar cells

Sulfonamide derivatives as semiconductor materials for organic optoelectronic devices, including photovoltaic (PV), have received considerable interest. In the present work, the synthesis of novel pyrogallol-sulfonamide derivatives based on a molecular hybridization approach yielded N-((4-((2,3,4-trihydroxyphenyl)diazenyl)phenyl)sulfonyl)acetamide (N-DPSA). The techniques of spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), and mass spectrum were utilized to identify the structural composition of the synthesized N-DPSA. The new N-DPSA was investigated by Hall-effect measurement to prove the positive charge carrier (hole mobility) with mobility and conductivity of 2.39 × 103 cm2/Vs and 1.76 × 10–1 1/Ω cm, respectively. Consequently, N-DPSA could be proposed as a strong candidate as a p-type semiconductor (hole transport layer (HTL)). The optical energy gap was computed at 2.03 eV, indicating the direct optical transition nature of N-DPSA. The elaborated molecular semiconductor's thermal features, molecular modelling, and electronic energy levels were also investigated. The new N-DPSA at various concentrations provided easy synthesis, cheap cost, high performance, and a straightforward design approach for a possible HTL in effective perovskite solar cells (PSCs). A PCE of 7.3% is shown for the N-DPSA-based PSC at its optimal concentration.

Pressure-Induced Structural Phase Transition and Fluorescence Enhancement of Double Perovskite Material Cs2NaHoCl6

Cs2NaHoCl6, a double perovskite material, has demonstrated extensive application potential in the fields of anti-counterfeiting and optoelectronics. The synthesis of Cs2NaHoCl6 crystals was achieved using a hydrothermal method, followed by the determination of their crystal structures through single crystal X-ray diffraction techniques. The material exhibits bright red fluorescence when exposed to ultraviolet light, confirming its excellent optical properties. An in situ high-pressure fluorescence experiment was conducted on Cs2NaHoCl6 up to 10 GPa at room temperature. The results indicate that the material possibly undergoes a structural phase transition within the pressure range of 6.9–7.9 GPa, which is accompanied by a significant enhancement in fluorescence. Geometric optimization based on density functional theory (DFT) revealed a significant decrease in the bond lengths and crystal volumes of Ho-Cl and Na-Cl across the predicted phase transition range. Furthermore, it was observed that the bond lengths of Na-Cl and Ho-Cl reach an equivalent state within this phase transition interval. The alteration in bond length may modify the local crystal field strength surrounding Ho3+, consequently affecting its electronic transition energy levels. This could be the primary factor contributing to the structural phase transition.

Alkaline titanium carbide (MXene) engineering ultrafine non-noble nanocatalysts toward remarkably boosting hydrogen evolution from ammonia borane hydrolysis

The rational design of cost-effective and stable heterogeneous nanocatalysts with high activities is vital yet challenged for utilization of sustainable hydrogen fuel. Herein, we report a novel surficial alkaline functional strategy for immobilization of non-noble CuCo nanoparticles (NPs) on diamine-alkalized-functionalized Ti3C2 surfaces (CuCo/PDA-Ti3C2). By virtue of coordination effect, ultrafine CuCo NPs with the size of 1.8 nm were well dispersed on Ti3C2 surface. Strikingly, the optimized CuCo/PDA-Ti3C2 nanocatalyst presents an impressive catalytic performance toward ammonia borane hydrolysis (ABH) without any additive, with a completed conversion and a high turnover frequency (TOF) value of 71.8 molH2molcat−1min−1 at mild condition. The alkaline amine groups induced a strong support-metal synergistic interaction (SMSI) to not only regulate the localized charge distribution and electron energy levels near active sites, but also optimize the surface d center and adsorption/desorption behavior, resulting in an accelerating O-H bond cleavage in water molecular. This work presents a novel and universal strategy for developing alkaline titanium carbide (MXene)-based heterogeneous nanocatalysts for hydrogen energy society.

Heterojunction interface engineering enabling high transmittance and record efficiency in Sb2S3 semitransparent solar cell

Antimony sulfide (Sb2S3) is an auspicious contender for semitransparent and tandem solar cells owing to its exceptional optoelectronic characteristics. Yet, complex bulk and heterojunction defects hinder achieving optimal power conversion efficiency (PCE). Although CdS is an established electron transport layer (ETL) in Sb-chalcogenide solar cells benefitting from its exceptional electron mobility (350 cm2V–1s−1) and energy level alignments, its potential contribution has been deplorably overlooked in Sb2S3 semitransparent photovoltaics (STPV). Herein, an optimized TiO2/CdS double ETL strategy is embraced to counteract CdS absorption loss and mitigate the “deep cliff” conduction band off-set at TiO2/Sb2S3 heterojunction. Subsequently, an evolved chemical bath deposition strategy is proposed to deposit a uniform, faster, and comparatively more transparent Sb2S3 absorber layer. A systematic investigation of the absorber layer and in-depth analysis of carrier dynamics at heterojunctions advocate for the mitigation of charge accumulation and recombination at the interface, thereby pledging superior carrier transport. The advantageous gradient energy band alignment of TiO2/CdS/Sb2S3 realized a record PCE of 5.61 % for STPV. Furthermore, the semitransparent device is innovatively employed as a window, enabling transmitted light to be harvested by subsequent Sb2S3 solar cells. It maintains 18 % of its standalone PCE, thereby setting new benchmarks for its practical submissions.

Investigation of radiation-induced luminescence properties of high-density barium phosphate glasses doped with Ce3+

The Ce3+ doped barium-zinc-gadolinium-phosphate glass samples with composition 20BaCO3-10ZnO-8Gd2O3-(62- x)P2O5-x CeBr3 (where x=0.15,0.25,0.5, and 0.75 mol.%) were fabricated by employing melt-quenching traditional method. The PXRD studies were performed to verify the amorphous form of the fabricated glasses. FE-SEM was utilised to check the particle size and shape of prepared samples. The measurements of EDS were employed to find out the elements available in the glasses. Wideband emission was observed in the 300–400 nm range in the obtained spectra under X-ray and UV–VIS excitations, revealing a 5d-4f transition of Ce3+-ions. The detected excitation bands found broad for prepared glasses include 4f electronic energy level transitions belonging to Gd3+ and the 5d electronic energy levels belonging to the Ce3+ excitation energy band situated at 308 nm. The scintillation property was investigated with α-particles and γ-rays excitations using 241Am and 137Cs, 22Na radiation sources, respectively. The lifetime of the prepared glass samples was studied under 286 nm UV excitation and found 28.94 ± 0.12 ns as a short component and 166.47 ± 23.44 ns long component with 85 % and 15 % contributions, respectively for PBZG-0.25Ce glass sample.

Boosting Electrochemical Nitrate Reduction to Ammonia by Fe Doped CuO/Co3O4 Nanosheet/Nanowire Heterostructures.

The electrochemical nitrate reduction reaction (NO3 -RR) is a novel green method for ammonia synthesis. The development of outstanding NO3 -RR performance is based on reasonable catalyst. Metal oxides have garnered significant attention due to their exceptional electrical conductivity and catalytic properties. Doping serves as an effective strategy for enhancing catalyst performance due to its ability to change the electron cloud distribution and energy levels. In this study, we develop a heterojunction catalyst Fe doped copper oxide nanosheet and cobalt tetroxide nanowire growing on carbon cloth simultaneously (Fe-CuO@Co3O4/CC) via hydrothermal method. The well-designed Fe-CuO@Co3O4/CC has excellent NH3 yield (470.9 μmol h-1 cm-2) and Faraday efficiency (FE: 84.4 %) at -1.2 V versus reversible hydrogen electrode (vs. RHE). The heterostructure increases the specific surface area of the catalyst, and the possibility of contact between the catalyst and NO3 - ions, enhances the catalytic efficiency. In addition, the catalyst has excellent stability and can stably carry out the electrocatalytic nitrate reduction reaction (NO3 -RR), which provides a way for further research on the high-efficiency reduction of nitrate.

The electronic properties of a single electron in the GaAs/Ga1−xAlxAs oblate spheroidal quantum dot under the finite confinement potential

Quantum Dots, due to their fully quantized electronic states, have contributed to considerable progress in modern science and technology. Here we calculate the wave functions and energy spectrum of an electron confined in an oblate spheroidal quantum dot under the finite barrier potential condition, allowing the tailoring of the various energy states for specific applications. By calculating the electron wave functions outside the dot, we found that an infinite barrier is not a valid approximation for analyzing the optical properties of the structure. The effect of various geometrical and electrical characteristics of the structure, including the eccentricity, effective volume, and the height of barrier potential, is investigated. Additionally, the findings are compared with those found with prolate spheroidal quantum dot. The findings are further validated by comparing them to the exact electron energy level in a spherical quantum under the infinite barrier approximation.

Machine-Learning-Assisted Materials Discovery from Electronic Band Structure.

Traditional methods of materials discovery, often relying on intuition and trial-and-error experimentation, are time-consuming and limited in their ability to explore the vast design space effectively. The emergence of machine learning (ML) as a powerful tool for pattern recognition has opened exciting opportunities to revolutionize materials discovery. This work explores the application of ML techniques to assist in the discovery of materials using band structure data. The electronic band structure, which describes the energy levels of electrons in a material, holds vital information regarding its electronic and optical properties. The band structure data of 63,588 materials, including metals and insulators, have been retrieved from the Materials Project database. The data were grouped into 85 batches based on the band path in the first Brillouin zone. Three ML clustering algorithms were trained on the band structure data after performing feature selection and engineering, followed by noise reduction. The models were validated by comparing the materials' properties in a cluster.

Investigating the photocatalytic efficacy of a porous cuprous gallate (CuGa2O4) thick film

Abstract The study aimed to investigate the photocatalytic activity of porous copper gallate (CuGa2O4) thick film with significant wall dimensions. The thick film was meticulously fabricated using tape casting systems, with CuGa2O4 nanoparticles synthesized by Sol–Gel technique and subsequently transformed into gels for the tape casting process. Rietveld refinements were employed to elucidate the crystal structure and lattice parameters of the CuGa2O4 spinel oxide lattice. Moreover, electronic energy configurations and optical transmittance measurements were acquired through UV-visible spectrophotometry. The correlations between the crystal structure, band gap change and formation of electronic energy levels in relation to the photocatalytic performance of CuGa2O4 were explored. The comprehensive examination provides valuable insights into the complex interaction between material properties and photocatalytic behavior, offering a nuanced understanding of the potential applications of porous CuGa2O4 thick films in various technological fields.

Strain effects on electronic structure and optics of al-Doped monolayer GaS

This comprehensive study utilises rigorous first-principles calculations to meticulously investigate the influence of uniaxial tensile strain on the electronic configuration and optical behaviours of aluminium-doped gallium sulphide. The study highlights the modulation of electrical properties and optical responses in Al-doped monolayer GaS through the application of tensile strain. Notably, with increasing tensile strain, the bandgap value of the pristine GaS exhibits a pronounced decline, whereas the Al-doped variant maintains a more stable bandgap. A deeper exploration of the state density reveals the emergence of novel electronic states and energy levels in both the pristine and Al-doped monolayer GaS systems as tensile strain is applied. Crucially, the stabilising effect of the doped Al atoms minimises variations in the state density profiles of the Al-doped monolayer GaS systems, in contrast to their pristine counterparts. This result implies that fine control of the electrical structure and optical characteristics of Al-doped monolayer GaS may be achieved by the application of uniaxial tensile strain. The optoelectronic characteristics of GaS and its doped systems are explained in detail by these discoveries, which also offer a crucial theoretical foundation and direction for the use of these materials in optoelectronic devices.

Systematic Analysis on The Development and Potential Use of Novel Semiconductors

Silicon-based transistors and integrated circuits, crucial for modern technology, are facing limitations due to scaling constraints. As transistors shrink, their performance is capped, affecting advanced technologies like AI, IoT, and 5G. Gallium nitride (GaN), with a melting point 200°C higher than silicon, presents a promising alternative due to its superior high-power and high-frequency performance. This essay reviews silicon’s semiconductor limitations and highlights the advancements in silicon carbide and Gan. The basic theories, such as electron mobility, energy level and covalent bond, are analyzed, and it is found that GaN is better than Sic and Si, but the three examples of semiconductors have different development fields in different fields. It compares the benefits of traditional silicon with these novel semiconductors, focusing on high-frequency and high-temperature performance. The essay also discusses current development, issues, and future predictions in semiconductor technology. Exploring new materials like GaN and silicon carbide addresses the technical challenges of silicon and enhances device performance, broadening technological possibilities.