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Investigating effect of strain on electronic and optical properties of lead free double perovskite Cs2AgInCl6 solar cell compound: A first principle calculation
摘要： Despite serious problems associated with toxicity of lead, lead halide perovskite based solar cells have resulted with remarkable efficiency and hence gained much interest. To overcome this aspect, numerous solutions are attempted by researchers which include the development of new environmental friendly lead free double perovskite (DP) photovoltaic materials. Enlightening on the same line, we report first principle calculations on electronic and optical properties of Cs2AgInCl6 solar photovoltaic materials. Present opto-electronic computations for lead free DP compound, have been performed using the full potential linearized augmented plane wave method. In present investigations, we have adopted exchange and correlation potentials prescribed by Perdew et al. and the most accurate Tran-Blaha modified Becke-Johnson. Both exchange and correlation potential computations are performed with and without spin orbit coupling. Results obtained for electronic and optical properties are validated by systematic comparison with available experimental data. Reasonable reconciliation between investigated results and the available experimental data, endorse accuracy of present computations. To identify the effect of strain on energy gap and hence on the optical properties of Cs2AgInCl6 compound, computations of electronic and optical properties have also been performed under the different values of strain application.
关键词： Density functional theory,Optical properties,Solar cells,Electronic structure
更新于2025-09-12 10:27:22
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A computational study of the electronic structure and optical properties of the complex TeO<sub>2</sub>/TeO<sub>3</sub> oxides as advanced materials for nonlinear optics
摘要： Electronic structure of series of tellurium oxide crystals within the TeO2—TeO3 binary system is studied with generalized gradient approximation to DFT, hybrid DFT-HF method with the PBE0 and B3LYP exchange-correlation functionals and with quasiparticle G0W0 approach. Comparison with available experimental data revealed significant underestimation of the band gap values within DFT. The hybrid DFT-HF method leads to slightly overestimated values of the bandgap, and the best agreement with experimental data provides the “one-shot” G0W0 calculations starting from Kohn-Sham solutions. The electronic structure of tellurium oxides is discussed in details. It is found that the bandgap value decreases proportionally to fraction of tellurium atoms in octahedral coordination. This change is due to formation of gap states by 5s(Te) electrons which do not participate in Te(VI)–O bonding. Dielectric susceptibilities are calculated within Random Phase approximation for the series of tellurium oxides and high nonlinear properties of the compounds are predicted by empirical Miller’s rule.
关键词： Ab initio,DFT,tellurium oxides,GW,nonlinear optics,electronic structure
更新于2025-09-12 10:27:22
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Electronic structure of hydroxylated La@C <sub/>82</sub> endohedral metallofullerene: implications on photovoltaic cells
摘要： The good performance of a photovoltaic device requires fitting a series of parameters related to electronic structure of materials. Since it is well-known that fullerenol is an excellent electron acceptor with excellent electron conductivity, in this paper we analyse the electronic levels, energy gaps, absorption spectra and electron mobility of hydroxylated La@C82 (La@C82(OH)n, n = 0?32) endohedral metallofullerene. Furthermore, calculations was performed on one unit of three donor polymers with low energy of the lowest unoccupied molecular orbital and on the well-known accep- tor fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) in order to compare the electronic structure and possible donor–acceptor combinations. Interestingly, high coatings have larger energy gap between the highest occupied molecular orbital of donor and the lowest unoccu- pied molecular orbital of acceptor, which is essential for increasing the open circuit voltage, which relates directly to power conversion efficiency. On the other hand, low coatings have better elec- tron mobility, which is essential in electron transport layers in perovskite-based solar cells. Finally, the absorption spectra of fullerenols were also calculated and compared with the widely used in organic solar cells PC61BM, obtaining a broader absorption spectrum in hydroxylated endohedral metallofullerenes helping in the performance of fullerenols for harvesting the solar spectrum.
关键词： density functional theory,absorption spectra,Solar cell,electronic structure tuning,endohedral metallofullerene
更新于2025-09-12 10:27:22
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Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots
摘要： Detailed theoretical studies of the electronic structure of (InGa)(AsSb)/GaAs/GaP quantum dots are presented. This system is unique since it exhibits concurrently direct and indirect transitions both in real and momentum space and is attractive for applications in quantum information technology, showing advantages as compared to the widely studied (In,Ga)As/GaAs dots. We proceed from the inspection of the con?nement potentials for k (cid:2)= 0 and k = 0 conduction and k = 0 valence bands, through the formulation of k · p calculations for k-indirect transitions, up to the excitonic structure of (cid:2) transitions. Throughout this process we compare the results obtained for dots on both GaP and GaAs substrates, enabling us to make a direct comparison to the (In,Ga)As/GaAs quantum dot system. We also discuss the realization of quantum gates.
关键词： excitonic structure,quantum dots,electronic structure,quantum gates,quantum information technology
更新于2025-09-11 14:15:04
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Study of charge injection in Ortho-, Meta- and Para-NKX-2553 in Dye-Sensitized Solar Cells: A theoretical approach
摘要： Dye sensitizers due to their significant role in the efficiency of Dye-Sensitized Solar Cells (DSSCs) have become the focal center of interest in recent years. In this study, NKX-2553 as one of the appealing metal-free organic dyes in different configurations of Ortho, Meta, and Para has been investigated. Parameters such as geometries, electronic structures, and optical properties, along with dipole moment, polarizability and first-order hyperpolarizability were calculated using density functional theory (DFT) and time-dependent DFT (TD-DFT). Results show that the Para-NKX-2553 is the best configuration in respect of increasing the charge injection in DSSCs. Moreover, according to our study, the efficiency of DSSCs can be improved through applying an external electric field in an appropriate direction.
关键词： Electric field,Charge injection,DFT,TD-DFT,Dye-sensitized solar cells,Electronic structure
更新于2025-09-11 14:15:04
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[IEEE 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Kyoto, Japan (2019.7.2-2019.7.5)] 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Influence of molybdenum oxide thickness, electronic structure, and work function on the performance of hole selective silicon heterojunction solar cells
摘要： Ultra-thin MoOx is capable of exhibiting high work function (< 6 eV), large band gaps (< 3 eV) are benefiting for surface passivation and hole selectivity layer in silicon solar cells instead of the doped layers due to high parasitic absorption. Importantly, MoOx electronic structure by oxygen dilution during the evaporation have influence to the MoOx work function and hence reduce hole injection. XPS study confirmed the electronic structure and chemical composition of the evaporated and annealed (Ar and O2 atmosphere) MoOx sample. TEM showed a clear interface contact between the ITO/MoOx/a-SiH(i) layers and no diffusion between the layers after annealed at 140 oC. Fabricated 10 nm thick MoOx/n-Si solar cells archived an efficiency of 20.04%, FF of 73.79 % and Jsc of 38.40 mA/cm2. A sever degradation in FF and Jsc was noticed by increasing the MoOx thickness due to diffusion of layers and high parasitic absorption of MoOx.
关键词： work function,silicon heterojunction solar cells,thickness,MoOx,electronic structure
更新于2025-09-11 14:15:04
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Low-Temperature Effect on the Electronic Structure and Spectral-Fluorescent Properties of Highly Dipolar Merocyanines
摘要： Absorption and fluorescence spectra of a vinylogous series of reversely solvatochromic merocyanines based on benzimidazole and malononitrile have been studied in frozen ethanol solutions at 77 K. It is found that they possess negative thermochromism – in contrast to both positively solvatochromic merocyanines and negatively solvatochromic symmetrical ionic polymethines – and even stronger negative thermofluorochromism. It has been deduced from the spectral data, that at low temperature their electronic structure becomes more dipolar, deviating substantially from the virtual ideal polymethine in both the ground and excited states. At that, owing probably to high polarity and ordering of frozen ethanol, the dipolarity of the studied merocyanines increases with the polymethine chain lengthening – the tendency not observed for them in common solvents. The conclusions, based on the spectra data analysis, have been verified by the (TD)DFT–PCM simulations of the dyes within the four-level scheme of electronic transitions.
关键词： Low-Temperature Effect,Spectral-Fluorescent Properties,Merocyanines,Quantum Chemistry,Electronic Structure,Molecular Structure,Spectroscopy
更新于2025-09-10 09:29:36
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Influence of Oxygen Vacancy Density on the Polaronic Configuration in Rutile
摘要： Polaronic con?gurations that were introduced by oxygen vacancy in rutile TiO2 crystal have been studied by the DFT + U method. It is found that the building block of TiO6 will expand when extra electron is trapped in the central Ti atom as polaron. With manually adjusting the initial geometry of oxygen vacancy structure, a variety of polaronic con?gurations are obtained after variable-cell relaxation. By calculating different sizes of supercell model, it is found that the most stable con?guration can be in?uenced by the density of oxygen vacancy. With increasing interaction between vacancies, the most stable polaronic con?guration change from small polaronic con?guration to mixed con?guration.
关键词： DFT + U,rutile,electronic structure,oxygen vacancies,polarons
更新于2025-09-10 09:29:36
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Charge Dynamics and Metal–Insulator Transition in Perovskite SrIr <sub/>1?</sub><i> <sub/>x</sub></i> Sn <i> <sub/>x</sub></i> O <sub/>3</sub>
摘要： We investigate the variation of charge dynamics upon the metal–insulator transition for perovskite SrIr1?xSnxO3 by employing the optical spectroscopy. The Dirac semimetal of SrIrO3 turns into the antiferromagnetic insulator with a gap of 0.1 eV by the Sn-substitution, accompanying the reconstruction of electronic structure on an energy scale of 1 eV. The spectral intensity of optical excitation between Je? = 1=2-orbitals is signi?cantly reduced with increasing x, while that between the Je? = 3=2- and 1=2-orbital shows merely moderate x-dependence. We anticipate that the substituted Sn signi?cantly renormalizes the e?ective bandwidth of Je? = 1=2-orbital while modestly changing the Je? = 3=2-orbital.
关键词： charge dynamics,optical spectroscopy,electronic structure,Je? = 3=2-orbital,perovskite,metal–insulator transition,Dirac semimetal,Je? = 1=2-orbitals,SrIr1?xSnxO3,antiferromagnetic insulator,Sn-substitution
更新于2025-09-10 09:29:36
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Energetics and electronic structures of polymeric all-benzene hollow-cages and planar networks
摘要： We studied the energetics and electronic structure of polymerized benzene hollow-cages and sheet using the density functional theory with the generalized gradient approximation. The energetics and electronic structure of the polymeric benzene cages and sheet depend on their size and dimensionality. Because of the symmetric network topology as well as the constituent benzene units, the cages possess highly bunched states around the Fermi level. The energy gap between the highest occupied and the lowest unoccupied states of the cages is approximately proportional to their curvature, owing to the decrease of the strain. The polymerized benzene sheet is a direct gap semiconductor with the gap of 2.4 eV between the less dispersive states of the highest branch of the valence and the lowest branch of the conduction bands.
关键词： density functional theory,electronic structure,planar networks,polymerized benzene,hollow-cages
更新于2025-09-10 09:29:36