Direct and indirect band gaps ≈ Direct and indirect band gaps
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Parity-Forbidden Transitions and Their Impact on the Optical Absorption Properties of Lead-Free Metal Halide Perovskites and Double Perovskites Open
Using density-functional theory calculations, we analyze the optical\nabsorption properties of lead (Pb)-free metal halide perovskites\n(AB$^{2+}$X$_3$) and double perovskites (AB$^+$B$^{3+}$X$_6$) (A = Cs or\nmonovalent organic ion, B$^{2…
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Structural Diversity in White-Light-Emitting Hybrid Lead Bromide Perovskites Open
Hybrid organic-inorganic halide perovskites are under intense investigations because of their astounding physical properties and promises for optoelectronics. Lead bromide and chloride perovskites exhibit intrinsic white-light emission bel…
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Composition design, optical gap and stability investigations of lead-free halide double perovskite Cs<sub>2</sub>AgInCl<sub>6</sub> Open
Stable double perovskite Cs2AgInCl6 has been reported as a direct gap semiconductor with a wide band gap of 3.23 eV obtained experimentally and 3.33 eV obtained by DFT calculation.
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Thin-Film Deposition and Characterization of a Sn-Deficient Perovskite Derivative Cs<sub>2</sub>SnI<sub>6</sub> Open
In this work, we describe details of a two-step deposition approach that enables the preparation of continuous and well-structured thin films of Cs2SnI6, which is a one-half Sn-deficient 0-D perovskite derivative (i.e., the compound can al…
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Indirect to direct bandgap transition in methylammonium lead halide perovskite Open
Unusually long charge carrier lifetime in methylammonium lead halide perovskites is a result of the Rashba-split indirect bandgap. At high pressure the bandgap becomes purely direct, with shorter carrier lifetime and higher radiative effic…
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Limitations of the Tauc Plot Method Open
The Tauc plot is a method originally developed to derive the optical gap of amorphous semiconductors such as amorphous germanium or silicon. By measuring the absorption coefficient α ( hν ) and plotting versus photon energy hν , a value fo…
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Direct-bandgap emission from hexagonal Ge and SiGe alloys Open
Silicon crystallized in the usual cubic (diamond) lattice structure has dominated the electronics industry for more than half a century. However, cubic silicon (Si), germanium (Ge) and SiGe alloys are all indirect-bandgap semiconductors th…
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Tunable Magnetism and Extraordinary Sunlight Absorbance in Indium Triphosphide Monolayer Open
Atomically thin two-dimensional (2D) materials have received considerable research interest due to their extraordinary properties and promising applications. Here we predict the monolayered indium triphosphide (InP3) as a new semiconductin…
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Temperature-Dependent Optical Band Gap in CsPbBr<sub>3</sub>, MAPbBr<sub>3</sub>, and FAPbBr<sub>3</sub> Single Crystals Open
Single crystals represent a benchmark for understanding the bulk properties of halide perovskites. We have indeed studied the dielectric function of lead bromide perovskite single crystals (MAPbBr3, CsPbBr3 and for the first time FAPbBr3) …
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Investigation on the electronic structure, optical, elastic, mechanical, thermodynamic and thermoelectric properties of wide band gap semiconductor double perovskite Ba<sub>2</sub>InTaO<sub>6</sub> Open
In the present paper, double perovskite Ba2InTaO6 was investigated in terms of its structural, electronic, optical, elastic, mechanical, thermodynamic and thermoelectric properties using density-functional theory (DFT).
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Low Band Gap Conjugated Semiconducting Polymers Open
Important parameters of an organic semiconductor material are the electronic band gap ( E g ) and the position of highest occupied and lowest unoccupied bands versus vacuum. These bands are called valence and conduction band for inorganic …
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Near-Direct Bandgap WSe<sub>2</sub>/ReS<sub>2</sub> Type-II pn Heterojunction for Enhanced Ultrafast Photodetection and High-Performance Photovoltaics Open
Pn heterojunctions comprising layered van der Waals (vdW) semiconductors have been used to demonstrate current-rectifiers, photodetectors, and photovoltaic devices. However, a direct or near-direct heterointerface bandgap for enhanced phot…
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Universal Mechanism of Band-Gap Engineering in Transition-Metal Dichalcogenides Open
van der Waals two-dimensional (2D) semiconductors have emerged as a class of materials with promising device characteristics owing to the intrinsic band gap. For realistic applications, the ideal is to modify the band gap in a controlled m…
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Cs<sub>2</sub>PbI<sub>2</sub>Cl<sub>2</sub>, All-Inorganic Two-Dimensional Ruddlesden–Popper Mixed Halide Perovskite with Optoelectronic Response Open
The two-dimensional Ruddlesden-Popper (RP) phases are an important class of halide perovskites with versatile optoelectronic properties. So far, only organic-inorganic hybrid RP phases involving long organic spacers were reported in this c…
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Thickness dependent electronic properties of Pt dichalcogenides Open
Platinum-based transition metal dichalcogenides have been gaining renewed interest because of the development of a new method to synthesize thin film structures. Here, using first-principles calculation, we explore the electronic propertie…
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Electronic, vibrational, elastic, and piezoelectric properties of monolayer Janus MoSTe phases: A first-principles study Open
By performing density functional theory based first-principles calculations, the electronic, vibrational, elastic, and piezoelectric properties of two dynamically stable crystal phases of monolayer Janus MoSTe, namely $1H$-MoSTe and $1{T}^…
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Electronic and optical properties of vacancy ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; and X = Cl, Br, I): a first principles study Open
The highly successful PBE functional and the modified Becke–Johnson exchange potential were used to calculate the structural, electronic, and optical properties of the vacancy-ordered double perovskites A 2 BX 6 (A = Rb, Cs; B = Sn, Pd, Pt…
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Ultrafast Electronic Band Gap Control in an Excitonic Insulator Open
We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor Ta_{2}NiSe_{5} investigated by time- and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of F_{…
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Valence and conduction band tuning in halide perovskites for solar cell applications Open
We performed density functional calculations aimed at identifying the atomistic and electronic structure origin of the valence and conduction band, and band gap tunability of halide perovskites ABX3 upon variations of the monovalent and bi…
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Analysis of direct band gap A2ScInI6 (A=Rb, Cs) double perovskite halides using DFT approach for renewable energy devices Open
Double perovskite halides are probable renewable energy generation materials that are believed to fulfill the requirements for solving energy scarcity problems. Therefore, investigations of these hallides have emerging applications in the …
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First‐principle calculations of optical properties of monolayer arsenene and antimonene allotropes Open
Recently a stable monolayer of antimony in buckled honeycomb structure called antimonene was successfully grown on 3D topological insulator Bi 2 Te 3 and Sb 2 Te 3 , which displays novel semiconducting properties. By first‐principle calcul…
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Strain-Modulated Bandgap and Piezo-Resistive Effect in Black Phosphorus Field-Effect Transistors Open
Energy bandgap largely determines the optical and electronic properties of a semiconductor. Variable bandgap therefore makes versatile functionality possible in a single material. In layered material black phosphorus, the bandgap can be mo…
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Structural, vibrational, and electronic properties of single-layer hexagonal crystals of group IV and V elements Open
Sevim, Koray/0000-0002-6150-8954; Sevincli, Haldun/0000-0002-1896-2588; Ozbal, Gozde/0000-0002-6265-964X; Ozdamar, Burak/0000-0001-7185-1978
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Band Gap Engineering of Hexagonal SnSe2 Nanostructured Thin Films for Infra-Red Photodetection Open
We, for the first time, provide the experimental demonstration on the band gap engineering of layered hexagonal SnSe 2 nanostructured thin films by varying the thickness. For 50 nm thick film, the band gap is ~2.04 eV similar to that of mo…
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Band Tailing and Deep Defect States in CH<sub>3</sub>NH<sub>3</sub>Pb(I<sub>1–<i>x</i></sub>Br<sub><i>x</i></sub>)<sub>3</sub> Perovskites As Revealed by Sub-Bandgap Photocurrent Open
Organometal halide perovskite semiconductors have emerged as promising candidates for optoelectronic applications because of the outstanding charge carrier transport properties, achieved with low-temperature synthesis. In this paper, we pr…
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Stability of single-layer and multilayer arsenene and their mechanical and electronic properties Open
Using first-principles spin-polarized density functional theory, we carried out an analysis on the atomic structure, stability, energetics, and mechanical and electronic properties of single-layer structures of arsenene. These are buckled …
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Defect-Tolerant Monolayer Transition Metal Dichalcogenides Open
Localized electronic states formed inside the band gap of a semiconductor due to crystal defects can be detrimental to the material's optoelectronic properties. Semiconductors with a lower tendency to form defect induced deep gap states ar…
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Optical Band Gap Estimation of ZnO Nanorods Open
The optical band gap energy of ZnO nanorods was estimated by different methods found in literature. These nanorods were deposited onto TiO2 covered borosilicate glass substrates by aerosol assisted chemical vapor deposition. Characterizati…
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Chemical Vapor Deposition of Monolayer Mo1−xWxS2 Crystals with Tunable Band Gaps Open
Band gap engineering of monolayer transition metal dichalcogenides, such as MoS 2 and WS 2 , is essential for the applications of the two-dimensional (2D) crystals in electronic and optoelectronic devices. Although it is known that chemica…
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Unified theory of direct or indirect band-gap nature of conventional semiconductors Open
Although the direct or indirect nature of the bandgap transition is an\nessential parameter of semiconductors for optoelectronic applications, the\nunderstanding why some of the conventional semiconductors have direct or\nindirect bandgaps…