Effective Mass Of Charge Carriers Research Articles

A Detailed First‐Principles Study of the Structural, Elastic, Thermomechanical, and Optoelectronic Properties of Binary Rare‐Earth Tritelluride NdTe3

AbstractRare‐earth tritellurides (RTe3) are popular for their charge density wave (CDW) phase, magnetotransport properties, and pressure‐induced superconducting state among other features. In this literature, Density functional theory is exploited to study various properties of NdTe3. The calculated elastic and thermomechanical parameters, which are hitherto untouched for any RTe3, uncover soft, ductile, highly machinable, and damage‐tolerant characteristics, as well as highly anisotropic mechanical behavior of this layered compound. Its thermomechanical properties make it a prospective thermal barrier coating material. Band structure, density of states, Fermi surfaces, and various optical functions of the material are reported. The band structure demonstrates highly directional metallic nature. The highly dispersive bands indicate very low effective charge carrier mass for the in‐plane directions. The Fermi surfaces display symmetric pockets, including signs of nesting, bilayer splitting among others, corroborating previous works. The optical spectra expose high reflectivity across the visible region, while absorption is high in the ultraviolet region. Two plasma frequencies are noticed in the optical loss function. The optical conductivity, reflectivity, and absorption reaffirm its metallic properties. The electronic band structure manifests evidence of CDW phase in the ground state.

Theory of Electron Transport in Two-Barrier Five-Layer Semiconductor Structures

The dependence of the transparency coefficient of a five-layer two-barrier structure on the electron energy and the ratio of the widths of two neighboring potential barriers is calculated. It is shown that the extremum of the transparency coefficient significantly depends on the geometric dimensions of the structure layers. In a symmetric five-layer two-barrier semiconductor structure, the condition for the occurrence of "resonant" electron transitions is defined. It is demonstrated that the mechanism of such (resonant) transitions is explained by the interference of de Broglie waves of electrons in the potential well, where the phases of de Broglie waves are determined by the geometric dimensions of the structure, and their amplitudes - by the ratio of the carrier energy to the height of the potential barrier. It has been established that with an increase in the effective mass of charge carriers, the number of intersections of the quantities fR (ξ) and ((1-2ξ))/(√(ξ-ξ2) increases. These intersections determine the dimensionally-quantized levels where electrons are localized.

Tailoring Polaron Dimensions in Lead-Tin Hybrid Perovskites.

Charge carriers in the soft and polar perovskite lattice form so-called polaron quasiparticles, charge carriers dressed with a lattice deformation. The spatial extent of a polaron is governed by the material's electron-phonon interaction strength, which determines charge carrier effective mass, mobility, and the so-called Mott polaron density, that is, the maximum stable density of charge carriers that a perovskite can support. Despite its significance, controlling polaron dimensions has been challenging. Here, experimental substantial tuning of polaron dimensions is reported by lattice engineering, through Pb/Sn substitution in CH3NH3SnxPb1-xI3. The polaron dimension is deduced from the Mott polaron density, which can be composition-tuned over an order of magnitude, while charge carrier mobility occurs through band transport, and remains substantial across all compositions, ranging from 10s to 100 scm2V s-1 at room temperature. The effective modulation of polaron size can be understood by considering the bond asymmetry after carrier injection as well as the random spatial distribution of Pb/Sn ions. This study underscores the potential for tailoring polaron dimensions, which is crucial for optimizing applications prioritizing either high charge carrier density or high mobility.

Systematic investigation on the rational design and optimization of bi-based metal oxide semiconductors in photocatalytic applications

To address the global energy shortage and mitigate greenhouse gas emissions on a massive scale, it is critical to explore novel and efficient photocatalysts for the utilization of renewable resources. Bi-based metal oxide (Bi x MO y ) semiconductors composed of bismuth, transition metal, and oxygen atoms have demonstrated improved photocatalytic activity and product selectivity. The vast number of element combinations available for Bi x MO y materials provides a huge compositional space for the rational design and isolation of promising photocatalysts for specific applications. In this study, we have systematically investigated the electronic and optical properties over Bi2O3 and a series of selected Bi x MO y group materials (BiVO4, BiFeO3, BiCoO3, and BiCrO3) by calculating band structure, basic optical property features, mobility and separation of charge carriers. It is clearly noted that the band gap and band edge position of the Bi x MO y group materials can be tuned in a wide range in comparison to Bi2O3. Similarly, the light response of Bi x MO y also can be broadened from the ultraviolet to the visible light region by adjusting the selection of transition metals. Additionally, the analysis of the effective mass of charge carriers of these materials further confirms their possibility in photocatalytic reaction applications because of the appropriate separation efficiency and mobility of carriers. A selection of experimental investigations on the crystal structure, composition, and optical properties of Bi2O3, BiVO4, and BiFeO3 as well as their catalytic performance in the degradation of methylene blue over was also conducted, which agree well with the theoretical predictions.

Emerging flat bands and spin polarization in nanodiamond island superlattices with varying carrier effective masses

For the first time, a set of regular 2D sp2/sp3 hybrid superlattices of nanodiamond islands confined between two graphene sheets (NDI-c2G) were proposed and explored using Density Functional Theory Periodic Boundary Conditions simulations. The fusion involves coronene and ovalene molecules with top and bottom graphene lattices, which can be treated with electron beam irradiation and atomic hydrogen at the nanodiamond site in three different configurations: (111)CD, (0001)HD, and (2¯110)HD. This creates distorted sp3 nanodiamond sublattices within the sp2 graphene fragments, serving as regions with confined electrons, making the charge carriers’ effective masses heavier. The presence of spin-splitting valence spin-up and conduction spin-down flat bands near the Fermi level in cubic ((111)CD-I and (111)CD-II) and hexagonal ((2¯110)HD)-II) superlattices resulted in magnetic moments of 3.99μB, 3.99μB, and 1.99μB per unit cell, respectively. Various configurations significantly impacted their electronic properties, resulting in spin-polarized and non-spin-polarized systems with flat bands near the Fermi level, exhibiting a semiconducting nature. The averaged spin moments per carbon atom were 0.16μB, 0.14μB, and 0.08μB, localized at the sp2/sp3 interfaces of the nanodiamond sites. Analysis of the electronic states, band structure, charge carrier effective masses, and spin density distribution suggests NDI-c2G shares similar electronic nature to strongly correlated twisted bilayer graphenes at small magic angles.

Structural, elastic, electronic, optical and anisotropy properties of newly quaternary Tl2HgGeSe4 via DFPT predictions associated to XPES and RS experiments

In the present work, we report on theoretical studies of thermodynamic properties, structural and dynamic stabilities, dependence of unit-cell parameters and elastic constants upon hydrostatic pressure, charge carrier effective masses, electronic and optical properties, contributions of interband transitions in the Brillouin zone of the novel Tl2HgGeSe4 crystal. The theoretical calculations within the framework of the density-functional perturbation theory (DFPT) are carried out employing different approaches to gain the best correspondence to the experimental data. The present theoretical data indicate the dynamical stability of the title crystal and they reveal that, under hydrostatic pressure, it is much more compressible along the a-axis than along the c-axis. Strikingly, the charge effective mass values (me∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$m_{e}^{{^{*} }}$$\\end{document} and mh∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$m_{h}^{{^{*} }}$$\\end{document}) vary considerably when the high symmetry direction changes indicating a relative anisotropy of the charge-carrier’s mobility. Furthermore, the Young modulus and compressibility are characterized by the maximum and minimum values (Emax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E^{max}$$\\end{document} and Emin\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E^{\\min }$$\\end{document}) and (βmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta^{max}$$\\end{document} and βmin\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta^{\\min }$$\\end{document}) that are equal to (62.032 and 28.812) GPa and (13.672 and 6.7175) TPa–1, respectively. Additionally, we have performed calculations of the Raman spectra (RS) and reached a good correspondence with the experimental RS spectra of the Tl2HgGeSe4 crystal. The XPES associated to RS constitutes powerful techniques to explore the oxidized states of Se and Ge in Tl2HgGeSe4 system.

Electronic Properties of Group-III Nitride Semiconductors and Device Structures Probed by THz Optical Hall Effect.

Group-III nitrides have transformed solid-state lighting and are strategically positioned to revolutionize high-power and high-frequency electronics. To drive this development forward, a deep understanding of fundamental material properties, such as charge carrier behavior, is essential and can also unveil new and unforeseen applications. This underscores the necessity for novel characterization tools to study group-III nitride materials and devices. The optical Hall effect (OHE) emerges as a contactless method for exploring the transport and electronic properties of semiconductor materials, simultaneously offering insights into their dielectric function. This non-destructive technique employs spectroscopic ellipsometry at long wavelengths in the presence of a magnetic field and provides quantitative information on the charge carrier density, sign, mobility, and effective mass of individual layers in multilayer structures and bulk materials. In this paper, we explore the use of terahertz (THz) OHE to study the charge carrier properties in group-III nitride heterostructures and bulk material. Examples include graded AlGaN channel high-electron-mobility transistor (HEMT) structures for high-linearity devices, highlighting the different grading profiles and their impact on the two-dimensional electron gas (2DEG) properties. Next, we demonstrate the sensitivity of the THz OHE to distinguish the 2DEG anisotropic mobility parameters in N-polar GaN/AlGaN HEMTs and show that this anisotropy is induced by the step-like surface morphology. Finally, we present the temperature-dependent results on the charge carrier properties of 2DEG and bulk electrons in GaN with a focus on the effective mass parameter and review the effective mass parameters reported in the literature. These studies showcase the capabilities of the THz OHE for advancing the understanding and development of group-III materials and devices.

Calculation electrical conductivity a two-dimensional electron gas of AlGaN/GaN-based transistors with high electron mobility

An analytical expression of the integral electrical conductivity of a semiconductor nanolayer, the charge carriers of which are located in a triangular quantum well, is obtained. The isoenergetic surface of the semiconductor material has the shape of a triaxial ellipsoid. The charge carrier behavior is described by the quantum Liouville equation. The dependence of electrical conductivity on dimensionless parameters is analyzed: the transverse electric field strength, the longitudinal electric field frequency, the charge carrier effective masses and the heterointerface specular coefficient. It is established that the conductivity of a triangular well compared to a rectangular well is more dependent on the effective mass, which to allow to select a material with the best high-frequency properties.

Optoelectronic properties of β-Cyclodextrin compound and doped with Na: Comparative study by experimental and DFT approaches

The chemical and physical properties of β-Cyclodextrin (β-CD) and doped with Na can be useful in drug delivery, organic solar cells and photoprotective applications. Physicochemical properties of pure β-CD and doped with Na were investigated by both density functional theory (DFT) and experimental methods. Theoretical calculations and the experimental measurements revealed that β-CD has a direct band gap of 3.44 and 4.14 eV, respectively. The optical absorption measurements indicate that band gap value decreases by Na doping to 3.09 eV. DOS spectra confirmed the stabilization of β-CD by the strong covalent bonds between C and O atoms. Obtained small effective mass of charge carriers with the high carrier mobility in β-CD show that it is a good candidate for using in the organic electronic applications. The significant isotropic behavior was observed in all optical spectra. The positive values of the real part of dielectric function confirm the dielectric nature of β-CD. Maximum dielectric polarization is observed at the ultraviolet region with the static dielectric constant of 2.03. High reflectivity at the ultraviolet region and beyond that confirm the photoprotective properties of β-CD compound against harmful solar radiations. There is a good agreement between the obtained experimental and DFT spectra. Our findings may be useful in design of new organic optoelectronic devices.

Ir noble metal atoms/clusters on graphene support: Insights from aberration corrected-STEM and density functional theory

The interactions of Iridium (Ir) noble metal atoms/clusters (Ir NMAs/NMCs) with graphene are investigated due to their remarkable catalytic performance, resulting from the use of 100 % metal atoms compared to nanoparticle counterparts. Using scanning transmission electron microscopy (STEM), various forms of Ir dispersed on graphene were observed, including single atoms, dimers, and trimers clusters. The STEM data further revealed inter-atomic distances of 2.83 Å and 2.96 Å for dimers and trimers which were 20 % and 17 % larger than the numbers found through density functional theory (DFT) calculations. The DFT calculations further showed that the Dirac-cone of graphene at Ir NMAs/NMCs locations changes to metallic form due to the emergence of energy states at the Fermi level. This effect results in non-zero effective masses of charge carriers but enhances their density of states (DOS) by 2-fold which is believed to increase the energy absorption efficiency of graphene in the infra-red range of radiation.

Enhanced carrier mobility and interface charge transfer in Bi–MoS2 heterojunctions induced by point defects

Semimetal Bi in contact with monolayer MoS2 (mMoS2) as a substrate reduced contact resistance. This phenomenon has attracted widespread attention. Presently, systematic research on defects in semimetal-TMDs heterojunctions remains limited. In this paper, nine types of vacancy defects (three S-vacancies at the heterojunction interface (VSI, II, III), three S-vacancies on the top layer (VSI, II, IIIt), one Mo vacancy (VMo), Mo–S double vacancies (VMo–S) and Mo–S triple vacancies (VMo–2S)) and defect-free structure (Perfect) are designed in mMoS2. Their impact on defect formation energy, Interface charge transfer, and carrier mobility in three-layer (3L)Bi(0001)-mMoS2 heterojunctions are studied by the First-Principles. The energy analysis indicates that in the 3LBi-mMoS2 contact, VS are more prone to formation than VMo, VSt, VMo–S and VMo–2S. At the same time VSⅡ has the lowest formation energy under Mo-rich environments. The analysis of electron and charge redistribution in the 3LBi-mMoS2 contact with defects indicates that defect generation introduces peaks at the Fermi level, enhancing the hybridization of Mo_4d and S_3p. The hybridization rate of electron orbitals in VMo surpasses that in VS and VSt, signifying that heterojunction structures with defects exhibit increased electron injection efficiency at the interface compared to Perfect. The charge carrier mobility of S and Mo defects in 3LBi-mMoS2 reveals a significant reduction in the effective mass of charge carriers due to vacancy defects. Due to the location of defects, heterojunctions exhibit anisotropy. Obtain Perfect > VMo > VSII (370.7 > 277>125.1 cm2V−1S−1) for the x-direction carrier mobility (μx), while VMo > Perfect > VSII (440.8 > 279.7>131.6 cm2V−1S−1) for the y-direction carrier mobility (μy). These findings offer practical insights for utilizing defects to modulate the electronic properties of Semimetal-MoS2 heterojunction interfaces.

Performance analysis of un-doped and doped titania (TiO ) as an electron transport layer (ETL) for perovskite solar cells.

Density functional theory (DFT) calculations are carried out on pure and doped rutile TiO . The bandgap (E ) for pristine, S-doped, Fe-doped, and Fe/S co-doped materials is direct, with values of 2.98 eV, 2.18 eV, 1.58 eV, and 1.40 eV. The effective mass of charge carriers (m*) and ratio of effective masses of holes to effective masses of electrons (R) are also investigated, and it is discovered that Fe/S co-doped materials have the lowest charge carrier recombination rate. The Fe/S co-doped material has the highest . of doped materials shifted into the visible range. Due to the high dopant concentration in Fe and Fe/S-doped cases, the E is lowered to a relatively small value; hence, only pristine and S-doped materials are verified as electron transport layer (ETL). A solar cell device analysis employing pure and S-doped rutile TiO as ETL is completed using DFT-derived parameters in SCAPS-1D modeling software for the first time. For the optimized solar cells, current-voltage (IV) characteristics, quantum efficiency (QE), capacitance-voltage (CV) characteristics, and capacitance-frequency (Cf) characteristics are provided. The aim of the present study is to improve efficiency of perovskite solar cell by doping as well as to improve accuracy of simulation by applying DFT extracted parameters as input. From the analysis, improvement is found in efficiency of doped TiO compared to un-doped TiO . The efficiency of the PSC with S-doped ETL is 1.418% higher than the PSC with un-doped ETL. Quantumwise Automistic Tool Kit (ATK) is used to extract DFT parameters. Using these DFT parameters as input in SCAPS-1D (Solar Cell Capacitance Simulator), solar cells for doped and un-doped material are simulated. The density functional theory (DFT)-based orthogonalized linear combination of atomic orbital (OLCAO) technique is used. Structural optimization is done using the LBFGS (Limited-memory Broyden-Fletcher-Goldfarb-Shanno). PBESol-GGA (Perdew-Burke-Ernzerhof solid-generalized gradient approximation) is applied as exchange correlation for calculating structural parameters, while MGGA-TB09 (meta-generalized gradient approximation-Tran and Blaha) is applied as exchange correlation for calculating optical and electronic properties.

Synthesis, Structure, and Properties of CuBiSeCl2: A Chalcohalide Material with Low Thermal Conductivity.

Mixed anion halide-chalcogenide materials have recently attracted attention for a variety of applications, owing to their desirable optoelectronic properties. We report the synthesis of a previously unreported mixed-metal chalcohalide material, CuBiSeCl2 (Pnma), accessed through a simple, low-temperature solid-state route. The physical structure is characterized through single-crystal X-ray diffraction and reveals significant Cu displacement within the CuSe2Cl4 octahedra. The electronic structure of CuBiSeCl2 is investigated computationally, which indicates highly anisotropic charge carrier effective masses, and by experimental verification using X-ray photoelectron spectroscopy, which reveals a valence band dominated by Cu orbitals. The band gap is measured to be 1.33(2) eV, a suitable value for solar absorption applications. The electronic and thermal properties, including resistivity, Seebeck coefficient, thermal conductivity, and heat capacity, are also measured, and it is found that CuBiSeCl2 exhibits a low room temperature thermal conductivity of 0.27(4) W K-1 m-1, realized through modifications to the phonon landscape through increased bonding anisotropy.

Combined DFT and MD simulation approach for the investigation of intrinsic material properties of T-phase Rb2Se monolayer

Two-dimensional monolayers are a prime class of materials due to their extensive spectrum of applications. In the present study, the material characteristics of the 1T-Rb2Se monolayer are investigated and analysed by employing the first-principles DFT calculations. The computations of structural, electronic, bonding nature, dynamical, optical, thermoelectric, and elastic properties of the theoretically predicted 1T-Rb2Se monolayer are effectuated. The 1T-Rb2Se monolayer displays a semiconducting nature with the energy gap quantified using various exchange-correlational potentials. The phonon and CPMD was deployed for the conclusions on the dynamical and thermal stabilities. With indirect band gap and good thermal response, the material will have possible applications in photovoltaics and thermoelectrics. Positive Poisson's ratio and elastic tensors validates the elastic strength of the monolayer. The effective masses of charge carriers and its relative ratio are determined from the energy band paraboloids with the deformation potentials for the accuracy of the relaxation time. The 1T-Rb2Se is electronically, ionically, dynamically, thermally, and elastically stable that confirms its feasibility for experimental studies.

Tuning structural and electronic properties of Stanene-based nanotube by strain and transverse electric field: First-principles investigation

In this work, we investigate the effects of applying strain and transverse electric field on the geometrical parameters and the electronic properties of (5,5) Stanene-based nanotube (SnNT) using density functional theory (DFT) calculations. The results reveal that the geometrical parameters such as diameter and buckling parameter affect by applying strain. Moreover, it is found that the studied nanotube exhibits direct and indirect band gap under tensile and compressive strain, respectively. In addition, the band gap energy decreases by increasing the compressive strain until the semiconductor to metal phase transition occurs. The external transverse electric field leads to separate degenerated states in the band structure and reduces the band gap energy of nanotube. Tuning the electric field induces semiconductor to metal transition. To further examine the electronic properties of (5,5) SnNT, the effective mass of charge carriers is calculated under applied strains and transverse electric fields.

First-Principles study of the structural, electronic, elastic, lattice dynamics and thermoelectric properties of the newly predicted half-heusler alloys NaYZ (Z = Si, Ge, Sn)

In this study, we applied Density Functional Theory (DFT) and Boltzmann Transport Theory to investigate the structural, electronic, lattice dynamic, elastic and thermometric properties of new half-Heusler compounds NaYZ (Z = Si, Ge, Sn). The structural optimization calculations revealed that the ZXY (1/4,1/2,0) phase have the most stable state with the least energy among others. Our calculated lattice constants in (Å) are found to be 6.861, 6.899, and 7.284 for NaYZ (Z = Si, Ge, Sn). Also, the calculated elastic constants satisfied the Born-Huang criteria and were found to be mechanically and elastically stable. The Density Functional Perturbation Theory (DFPT) was used to examined the lattice dynamics of the compounds and the results shown non-existence of negative frequencies all through dispersion band structures, thus all the compounds are dynamically stable. The Seebeck coefficient of the compounds at room temperature for the p-type (n-type) are 143.79 (−48.91) μ V/K, 132.49 (−48.86) μ V/K, 154.75 (−60.24) μ V/k for NaYZ (Z = Si, Ge, Sn). The modified Slack's approach was used to compute lattice thermal conductivity (kp) within the experimental range and the kp values obtained for NaYZ (Z = Si, Ge, Sn) at room temperature are 17.265 Wm −1 K −1, 14.671 W m−1K−1, 10.693 W m−1K−1, respectively. The computations of charge carriers relaxation time (τ = F(T)) as a function of temperature through deformation potential theory and the effective mass of charge carriers were used to evaluate the figure of merit (zT) for p-type and n-type of the materials. The maximum zT at 1200 K of τ = F(T) (τ = 10−13 s) are 1.76 (1.67), 1.73 (1.65), and 1.91 (1.88). These results show that τ = F(T) has improvement in determining the figure of merit as compared to the constant relaxation time (τ).

Ultralow Lattice Thermal Conductivity and Extraordinary Thermoelectric Performance in Highly Disordered CuIn7Se11 Layered Compound

AbstractSince the lattice thermal conductivity of thermoelectric materials is a relatively independent parameter, exploring semiconductor materials with intrinsically low lattice thermal conductivity is an important direction in the field of thermoelectric research. Herein, a high figure of merit ZT of 1.23 at 873 K and an exceptionally low lattice thermal conductivity of 0.18 W m−1 K−1 are realized in the n‐type CuIn7Se11 compound for the first time. The weak In─Se chemical bonds induce strong coupling between acoustic phonon and optical phonon with low frequency, leading to low sound velocity. The highly disordered configuration of Cu, In, and vacancies at In2, In3, and M sites, in conjunction with atomic‐scale slips and flips intensify phonon scattering. All these result in an intrinsically low thermal conductivity of the CuIn7Se11 compound. DFT calculation reveals that the density of states at the bottom of the conduction band is mainly contributed by the coupling between 4p orbitals of Se atoms and 5s orbitals of In atoms, featuring with a small effective mass. This small effective mass of charge carrier renders the CuIn7Se11 compound high carrier mobility of 435 cm2 V−1 s−1 at 300 K. Consequently, the CuIn7Se11 compound possesses an extraordinary thermoelectric performance

Rational Atom Substitution to Obtain Efficient, Lead‐Free Photocatalytic Perovskites Assisted by Machine Learning and DFT Calculations

AbstractInorganic lead‐free halide perovskites, devoid of toxic or rare elements, have garnered considerable attention as photocatalysts for pollution control, CO2 reduction and hydrogen production. In the extensive perovskite design space, factors like substitution or doping level profoundly impact their performance. To address this complexity, a synergistic combination of machine learning models and theoretical calculations were used to efficiently screen substitution elements that enhanced the photoactivity of substituted Cs2AgBiBr6 perovskites. Machine learning models determined the importance of d10 orbitals, highlighting how substituent electron configuration affects electronic structure of Cs2AgBiBr6. Conspicuously, d10‐configured Zn2+ boosted the photoactivity of Cs2AgBiBr6. Experimental verification validated these model results, revealing a 13‐fold increase in photocatalytic toluene conversion compared to the unsubstituted counterpart. This enhancement resulted from the small charge carrier effective mass, as well as the creation of shallow trap states, shifting the conduction band minimum, introducing electron‐deficient Br, and altering the distance between the B‐site cations d band centre and the halide anions p band centre, a parameter tuneable through d10 configuration substituents. This study exemplifies the application of computational modelling in photocatalyst design and elucidating structure–property relationships. It underscores the potential of synergistic integration of calculations, modelling, and experimental analysis across various applications.

Rational Atom Substitution to Obtain Efficient, Lead-Free Photocatalytic Perovskites Assisted by Machine Learning and DFT Calculations.

Inorganic lead-free halide perovskites, devoid of toxic or rare elements, have garnered considerable attention as photocatalysts for pollution control, CO2 reduction and hydrogen production. In the extensive perovskite design space, factors like substitution or doping level profoundly impact their performance. To address this complexity, a synergistic combination of machine learning models and theoretical calculations were used to efficiently screen substitution elements that enhanced the photoactivity of substituted Cs2 AgBiBr6 perovskites. Machine learning models determined the importance of d10 orbitals, highlighting how substituent electron configuration affects electronic structure of Cs2 AgBiBr6 . Conspicuously, d10 -configured Zn2+ boosted the photoactivity of Cs2 AgBiBr6 . Experimental verification validated these model results, revealing a 13-fold increase in photocatalytic toluene conversion compared to the unsubstituted counterpart. This enhancement resulted from the small charge carrier effective mass, as well as the creation of shallow trap states, shifting the conduction band minimum, introducing electron-deficient Br, and altering the distance between the B-site cations d band centre and the halide anions p band centre, a parameter tuneable through d10 configuration substituents. This study exemplifies the application of computational modelling in photocatalyst design and elucidating structure-property relationships. It underscores the potential of synergistic integration of calculations, modelling, and experimental analysis across various applications.

A theoretical–experimental study of KSr2Nb(3-x)TaxO10 (x = 0,1,2) systems as photocatalysts

Understanding the influence of structural changes arising from electronic characteristics is a significant challenge in novel material development. The Nb(V) and Ta(V) cations are pertinent due to their similar ionic radii across various coordinations. Layered perovskites (KSr2Nb(3-x)TaxO10, where x = 0,1, and 2) were synthesized using the solid-state method. These compounds were characterized employing experimental techniques and subjected to photocatalytic testing in a model reaction. Density Functional Theory simulations were conducted, confirming experimental data accuracy and prediction reliability. Evaluation of intra and inter-octahedral distortion and charge carrier effective masses were correlated with experimental outcomes. Remarkably, substituting Nb with Ta increased photocatalytic activity, suggesting a promising avenue for tailoring material properties.