Using hybrid density-functional calculations we investigate the effects of native point defects on electrical and optical properties ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$. We analyze formation energies, transition levels, local lattice relaxations for all defects. find that donor are in general more energetically favorable than acceptor defects, except near O-rich conditions, where oxygen interstitials indium vacancies have low energy $n$-type The vacancy is lowest-energy defect with level...

Methylammonium lead iodide (MAPbI₃) is an important light-harvesting semiconducting material for solar-cell devices.

In$_2$Se$_3$ is a semiconductor material that can be stabilized in different crystal structures (at least one 3D and several 2D layered have been reported) with diverse electrical optical properties. This feature has plagued its characterization over the years, reported band gaps varying an unacceptable range of 1 eV. Using first-principles calculations based on density functional theory HSE06 hybrid functional, we investigated structural electronic properties four phases In$_2$Se$_3$,...

$P$-type doping in oxides is usually difficult due to their low valence-band energy. In order make them $p$ type, the electronic structure of should be fundamentally changed; that is, occupied valence band raised significantly. Here, using first-principles calculations, we propose by adding a small amount ${\mathrm{Bi}}_{2}{\mathrm{O}}_{3}$ into ${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ form dilute ${({\mathrm{Bi}}_{x}{\mathrm{Ga}}_{1--x})}_{2}{\mathrm{O}}_{3}$ alloys and, more importantly, with...

Stability and maintenance of the crystal structure are main drawbacks application organic-inorganic perovskites in photovoltaic devices. The ΔT = 62 K robust shift structural phase transition observed here allows us to conduct a comprehensive study at room temperature tetragonal versus cubic on MAPbI3. absence for all-inorganic CsPbI3 samples confirms importance both orientation dynamics organic cations. Our results provide unique opportunity evaluate physical properties phases MAPbI3 same...

Chalcopyrites are a demonstrated material platform for realizing efficient thin-film photovoltaics, with the most well known Cu(In,Ga)Se2 (CIGS)-based solar cells exceeding 23%. Several factors, including flexibility in tuning absorber bandgap, enhanced surface treatments, and electrically benign nature of common defects responsible existing high performance future promise chalcopyrite-based photovoltaic devices. The introduction Cu-poor phases (also as ordered-vacancy compounds or OVCs)...

Abstract Alloys of ABX 3 halide perovskites (HP) exhibit unique phase behavior compared to traditional III‐V and II‐VI semiconductor alloys used in solar cells. While the latter typically have good mutual miscibility when their mixed components are size matched, phase‐segregate mismatched, HP show dark but can under light. Quantum mechanical calculations described herein reveal light‐induced defect formation migration hold key. Specifically, interaction between a halogen vacancy V X with...

We study the stability of corundum, gallia, and bixbyite structures ${\mathrm{Al}}_{2}{\mathrm{O}}_{3},{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$, ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ with density functional theory calculations. To artificially control relative position $d$ states within band structure, we add a Hubbard-like on-site Coulomb interaction to states. quantitatively show that smaller (larger) atomic radii favor corundum (bixbyte) which supports empirical models based on radius ratio...

In this study, a three-dimensional surface enhanced Raman scattering (SERS) substrate comprised of silver coated gold nanorods (Ag/AuNRs) decorated on electrospun polycaprolactone (PCL) fibers has been applied, for the first time, to quantitative analytical measurements various arsenic species: p-arsanilic acid ( pAsA), roxarsone (Rox), and arsenate (AsV), with demonstrated sensitivity below 5 ppb. AsV detection in solution common salt ions demonstrated, showing tolerance more complex...

Using density functional theory (DFT) calculations with the screened hybrid of Heyd, Scuseria, and Ernzerhof (HSE06), we study effects hydrostatic pressure on electronic properties LaAs. We focus band crossing near $X$ point that can make LaAs a topological semimetal, discussing results both DFT within generalized gradient approximation (GGA) HSE06 functional. find in DFT-GGA, under calculated equilibrium lattice parameter, displays between highest As $p$ lowest La $d$ due to overestimated...

Inorganic halide perovskites (HP's) of the CsPbX3 (X = I, Br, Cl) type have reached prominence in photovoltaic solar cell efficiencies, leading to expectation that they are a new class semiconductors relative traditional ones. Peculiarly, shown an asymmetry their ability be doped by holes vs. electrons. Indeed, both structural defect-induced doping as well extrinsic impurity-induced strangely often result HP's unipolar (dominantly p-type) with low free carriers' concentration. This raises...

Recent finds have revealed in metal halide perovskites the presence of lower local symmetry contributions especially cubic phase detriment to its high monomorphic structure (Pm-3m). We analyzed impact polymorphic nature CsBX3 inorganic (B = Ge, Sn, Pb; X Cl, Br, I) through first-principle calculations show how polymorphism contributes more material stability than their counterparts. Distinct trends can be seen for each halogen and series, revealing role (strong) spin–orbit coupling (SOC) on...

Good transparent conducting oxides (TCOs), such as ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$:Sn (ITO), usually combine large optical band gaps, essential for high transparency, with relatively small fundamental gaps due to low conduction-band minima, which favor $n$-type doping and enhance the electrical conductivity. It has been understood that are wider than because transitions between band-edge states forbidden. The mechanism blocking transitions, can play a crucial role in designing of...

The k · p method is a successful approach to obtain band structure, optical and transport properties of semiconductors it depends on external parameters that are obtained either from experiments, tight binding or ab initio calculations. Despite the widespread use method, systematic analysis stability accuracy its not usual in literature. In this work, we report theoretical framework determine state-of-the-art hybrid density functional theory including spin–orbit coupling, providing...

We quantified the bulk Rashba splitting and suppression in polymorphs of MA(Pb, Sn, Ge, or Si)I3 perovskites. The low-computational-cost DFT-1/2 quasiparticle correction was performed for all structures, combined with inclusion spin–orbit coupling (SOC) effects. presence SOC symmetry breaking from metal off-centering octahedral distortion are indispensable essential conditions splitting, whose magnitude emerges Pb → Si sequence. Additionally, provides energy bandgaps MAPbI3 (cubic,...

The interest in light-sensitive organic molecules, such as azobenzene, has increased because of their ability to functionalize two-dimensional layered systems and engineer electronic structure. In this work, we explore the azobenzene trans cis isomer adsorption on a molybdenum disulfide MoS2(0001) layer employing density functional theory (DFT) within van der Waals (vdW) corrections semilocal exchange–correlation functional. We found that aromatic rings lay parallel surface (two one isomer),...

Observation of large nonsaturating magnetoresistance in rare-earth monopnictides has raised enormous interest understanding the role its electronic structure. Here, by a combination molecular-beam epitaxy, low-temperature transport, angle-resolved photoemission spectroscopy, and hybrid density functional theory we have unveiled band structure LuSb, where electron-hole compensation is identified as mechanism responsible for this topologically trivial compound. In contrast to bulk single...

Quaternary chalcogenide materials offer a wide variety of chemical and physical properties, hence, those compounds have been widely studied for several technological applications. Recently, experimental studies found that the ${\mathrm{Cs}}_{2}{\mathrm{M}}^{\mathrm{II}}{\mathrm{M}}_{3}^{\mathrm{IV}}{\mathrm{Q}}_{8}$ family (${\mathrm{M}}^{\mathrm{II}}$ = $\mathrm{Mg}, \mathrm{Zn}, \mathrm{Cd}, \mathrm{Hg}, {\mathrm{M}}^{\mathrm{IV}}$ $\mathrm{Ge}, \mathrm{Sn}$ $\mathrm{Q}$ $\mathrm{S},...

The optical band gap, extracted from absorption measurements, defines the figure of merit for transparent conducting oxides (TCOs). In many oxides, such as [Formula: see text] or text], inversion symmetry introduces a selection rule that blocks transitions valence-band maximum to conduction-band minimum. This raises threshold and enlarges gap relative fundamental gap. Here, we present density-functional computations identifying two gaps, either which can be detected, depending on light...

Because of instability issues presented by metal halide perovskites based on methylammonium (MA), its replacement to Cs has emerged as an alternative improve the materials' durability. However, impact this electronic properties, especially gap energy and bulk Rashba splitting remains unclear since electrostatic interactions from organic cations can play a crucial role. Through first-principles calculations, we investigated how organic/inorganic properties MAPbI3 CsPbI3 perovskites. Although...

We have produced Fe-doped paramagnetic MAPbI3 microwires by using a novel strategy involving self-assembly growth process of [PbI6]4– octahedral chains in the presence liquid water. Structural and morphological studies confirmed that after dissociation recrystallization process, doped samples preserved both perovskite structure with tetragonal phase microwire shape, while X-ray photoelectron spectroscopy revealed mixed-valence Fe3+/Fe2+ ions negligible change PbI6 cage environment maximum...

Semiconductors with a wide band gap ($>3.0$ eV), high dielectric constant ($>10$), good thermal dissipation, and capable of $n$- $p$-type doping are highly desirable for high-energy power electronic devices. Recent studies indicate that ${\mathrm{ZnGa}}_{2}{\mathrm{O}}_{4}$ may be suitable these applications, standing out as an alternative to ${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$. The simple face-centered-cubic spinel structure results in isotropic optical properties, contrast the large...

Despite the large number of theoretical III-V semiconductor studies reported every year, our atomistic understanding is still limited. The limitations approaches to yield accurate structural and electronic properties on an equal footing, due unphysical self-interaction problem that mainly affects band gap spin-orbit splitting (SOC) in semiconductors and, particular, systems with similar magnitude SOC. In this work, we report a consistent study by using screening hybrid-density functional...

A comprehensive study on the correlations of structural, magnetic, and electronic properties a new disordered Nd2CoFeO6 double perovskite has been conducted. The lack strong divergence magnetic susceptibility suggests competition between interactions at phase transition TN = 246 K, which is confirmed by absence heat capacity peak. results indicate that Fe/Co spins form classical noninteracting paramagnetic state above T ≈ 2.2TN, while deviations are found intermediate temperatures indicating...