Energy band gap

The F2B slab model weakens the oscillations and calculations on F2B model quickly converge. However, the F2B model leads to artificial narrowness of band gap. Besides, when the number of layers increases, surface energy obtained from all three slab models approaches similar values. In particular, values of surface energy from DFT calculations converge to the experimental range for all three slab models.

8p dianmotminh02 03-05-2024 5 2   Download

Perovskite solar cells are known to belong to the third generation of solar cells. Owing to the ability to change the band gap energy when changing the material composition, it has a high absorption coefficient that reduces manufacturing costs and carrier mobility. and the diffusion length of large charged particles leads to higher efficiency, so compared to other types of solar cells of the same generation such as color sensitive batteries and quantum dot batteries, perovskite batteries have the most application prospects.

3p visergey 02-04-2024 2 0   Download

The adsorption of toxic gas molecules on Xenes (X = Si, Ge, Sn) has been studied by density functional theory (DFT). The optimized adsorption site of the adsorbates (CO, CO2, NO2) on Xenes (X = Si, Ge, Sn), the corresponding adsorption energies, band gap, band structure, and density of states of silicene, germanene, and stanene are discussed.

15p visharma 20-10-2023 6 2   Download

The induced magnetic properties and the interaction between the electrons in the valence and the conduction bands affect the positions of the energy band and the band-gap in DMS. The growth technology of DMS is quite sophisticated and the magnetic properties mainly depend on the impurity concentrations of the properly grown multicomponent compounds.

6p viberbers 09-08-2023 4 3   Download

Results of this investigation have been correlated with the films structural and optical properties. Among the structural properties, surface roughness and morphology, and crystalline quality of the films have been obtained by using the XRD and AFM methods. Additionally, optical properties such as band gap tune-ability and dielectric constant have been determined by spectroscopic ellipsometer.

7p viberbers 09-08-2023 4 3   Download

The study explores the mechanical, optoelectrical and photocatalytic properties of GeS and SnS structures by Density Function Theory (DFT) through Quantum Espresso software. The results show that the GeS and SnS structures are the semiconductor materials at equilibrium with band gaps of 1.75 eV and 1.4 eV, respectively.

8p vihawkeye 26-05-2023 8 2   Download

Metal oxide nanomaterials are widely used in many applications of renewable energy. Ytterbium oxide (Yb2 O3 ) also attracts attention due to its similar structure to ZnO (~3,26 eV) and TiO2 (~3,36 eV) in terms of bandgap energy. In this study, Yb2 O3 belonging to the lanthanide oxide family was produced as nanofiber forms by using the electrospinning technique, which allows for large-scale production, for the first time.

9p lyhuyenthu 31-01-2023 8 2   Download

"Structural and electrical properties of germanene nanoribbons doped with boron - A DFT study" using density functional theory (DFT) and VASP software, the formation energies, energy band structures, and density of states of the configurations are studied. The configuration for the smallest formation energy is the most optimal configuration, so this configuration is the most stable. The appearance of an external electric field changes the band gap and the energy band structure of the system.

8p lieuyeuyeu18 23-12-2022 14 3   Download

In the study "Structural and electronic properties of germanene adsorbing O2, N2, and H2 gases: A DFT study" DFT calculations under van der Waals corrections are utilized to investigate the adsorption mechanism of the O2, N2 and H2 gases on germanene. The first-principles physical quantities are sufficiently developed to determine the structural and electronic properties, including the adsorption energies, optimal structural parameters, the electronic band structures, the charge density distribution.

6p lieuyeuyeu18 23-12-2022 8 3   Download

A series of solution processable, wide band-gap host materials composed of carbazole and tetraphenylsilane groups were designed and synthesized. Their thermal, electrochemical, and photophysical properties were fully investigated. The introduction of bulky tetraphenylsilane and tert-butyl groups around the carbazole led to high glass transition temperatures (Tg) between 120 and 204◦C. The triplet energies (ET) of the synthesized materials were examined by low temperature (77 K) photoluminescence studies and determined as E T > 2.6 for all compounds.

24p langthannam 29-12-2021 7 0   Download

Mixed-phased Inx Sey thin film containing InSe, In2 Se3 and In6 Se7 phases was prepared by M-CBD method and characterized by X-ray diffraction, AFM, optical spectroscopy and J-V measurements. Structural, optical and electrical conductance properties were modified by annealing the films at different temperatures. Optical and morphological properties were also investigated dependently on temperature and concentration of cationic precursor solution.

13p langthannam 29-12-2021 12 0   Download

A novel alkoxy-bridged dithieno (3, 2-B:2’,3’-D) pyrrole (DTP) derivative was synthesized and its corresponding polymer poly(1,2-bis(2-(4H-dithieno[3,2-b:2’,3’-d]pyrrol-4-yl)ethoxy)ethane) (P(DTP-alkoxy-DTP)) was successfully obtained electrochemically. The effects of alkoxy bridge in the structure on the electrochemical and spectroelectrochemical properties of the polymer were also investigated in detail. The results showed that the polymer film exhibits multielectrochromic behavior and a low band gap of 1.82 eV.

10p tudichquannguyet 29-11-2021 11 1   Download

ZnO powder was synthesized via a hydrothermally assisted sol-gel method. Synthesis variables including Znprecursor type, pH value, time, and temperature of hydrothermal treatment were analyzed using the Taguchi approach. The experimental procedures were defined based on the L9 array for four variables in three levels. The influences of those variables on the response parameters, i.e. crystallite size, crystallinity, band gap energy (Eg), and degradation constants (k), were evaluated. XRD results and Eg values showed that ZnO wurtzite appeared to be the only crystalline phase in the samples.

12p tudichquannguyet 29-11-2021 14 1   Download

In this paper, we present one method to determine the band gap energy of ZnO and ZnO:Tb3 materials. ZnO:Tb3 material has prepared by forced hydrolysis method. All samples have zinc oxide hexagonal wurzite structure. The obtained results show that the energy of the band gap depends on Tb3 molar ratio.

6p tamynhan5 10-12-2020 8 1   Download

Optimized geometries, formation energy, phonon spectra, electronic band structure, and elastic tensor calculation has ensured the energetically, dynamical and mechanical stability for the sheets. Furthermore, the theoretically found nanosheet series possess an intrinsic wide direct band gap preserving from wurtzite tetragonal-based bonding. This high symmetry wide bandgap semiconductor nanosheet series and their derivatives are expected to have broad applications in photocatalysis, and biomedicine.

10p trinhthamhodang9 10-12-2020 12 2   Download

Borotellurite glasses were prepared by melt quenching technique. Amorphous nature of samples was confirmed through X-ray diffraction (XRD) patterns. Effect of B2O3 content on the structure of glass network was studied through Fourier-transform infrared spectroscopy (FTIR) spectra. Optical band gap and Urbach energy were found from analysis of optical absorption spectra. Thermal studies were carried out by using Differential thermal analyzer (DTA) measurements.

8p tamynhan6 14-09-2020 11 1   Download

The maximum ionic conductivity of 5.39 108 Scm1 at 303 K was observed for the 5 mol VO2 ions doped PVP polymer electrolyte film. From the UV-Visible absorption spectra in the wavelength range of 200-800 nm the direct and indirect optical energy band gaps and optical absorption edges were found decreased with the increase in the VO2 ion concentration.

7p tamynhan4 06-09-2020 11 1   Download

It has been reported in literature that studies have been conducted on electrical conductivity and dielectric properties of polymer blends with regard to storage and dissipation of electric and magnetic energies. These materials reveal numerous phenomena in optics, electronics and solid state physics.

9p tamynhan4 06-09-2020 13 2   Download

Bismuth dioxide selenide, Bi2O2Se, is a thermoelectric material that exhibits low thermal conductivity. Detailed understanding of the compounds band structure is important in order to realize the potential of this narrow band semiconductor. The electronic band structure of Bi2O2Se is examined using first - principles density functional theory and a primitive unit cell. The compound is found to be a narrow band gap semiconductor with very flat bands at the valence band maximum (VBM). VBM locates at points off symmetry lines. The energy surface at VBM is very flat.

12p nguyenxuankha_bevandan 14-08-2020 13 1   Download

A solid acid membranes based on poly (vinyl alcohol) (PVA), sodium bromide (NaBr) and phosphoric acid (H3PO4) were prepared by a solution casting method. The morphological, IR, electrical and optical properties of the (PVA)0.7(NaBr)0.3(H3PO4)xM solid acid membranes where x = 0.00, 0.85, 1.7, 3.4, 5.1 M were investigated. The variation of film morphology was examined by scanning electron microscopy (SEM) studies. FTIR spectroscopy has been used to characterize the structure of polymer and confirms the complexation of phosphoric acid with host polymeric matrix.

7p kethamoi1 17-11-2019 17 0   Download