Journal for Foundations and Applications of Physics
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First Principle Study on Lead-Free CH3NH3GeI3 and CH3NH3GeBr3 Perovskite solar cell using FHI-aims Code
Get PDFAn Ab-initio calculation in the framework of Density Functional Theory (DFT), as implemented in the FHI-aims package within Generalized Gradient Approximation (GGA) with the pbe parameterization was carried out in this work. Although methyl ammonium lead iodide (CH3NH3PbI3) has proven to be an effective photovoltaic material, there remains a main concern about the toxicity of lead. An investigation into the possible replacement of CH3NH3PbI3 with CH3NH3GeI3 and CH3NH3GeBr3 as the active layer in perovskite solar cell was carried out. The electronic band structure, band gap energy and dielectric constants were calculated for CH3NH3GeI3 and CH3NH3GeBr3. The effect of temperature on linear thermal expansion coefficient and temperature dependence of lattice constant were studied in the temperature range of 273 to 318 K. Band gap shift due to lattice expansion was also studied. The dielectric constants of these materials were also determined. The energy band gap calculated for CH3NH3GeI3 and CH3NH3GeBr3 at their respective equilibrium lattice constant are 1.606 and 1.925eV respectively. A numerical simulation with some of these materials as the active layer in a perovskite solar cell was performed using General-purpose Photovoltaic Device Model (GPVDM) and the conversion efficiency of the resulting solar cell was obtained. Conversion efficiency of 10% and 8.4% were obtained for CH3NH3GeI3 and CH3NH3GeBr3 respectively
Characterization of Indian pine Oleoresin and Evidence for the existence of Silicon compounds
Get PDFHerein we report the thermal behavior of the Indian pine oleoresin by thermogravimetric, differential thermal analysis (TG-DTA) and powder XRD studies. The natural oleoresin is amorphous as seen from powder XRD studies. However, when heated to a high temperature, it forms crystalline SiO2 with characteristic reflections of alpha-quartz (SiO2) as seen in powder XRD patterns. TG-DTA analysis shows that the amount of SiO2 obtained upon heating is about 75% of the initial resin mass, a huge proportion compared to a maximum of 20% reported in the literature from other plant sources. The FTIR spectra of the oleoresin and its organic extract show a band around 1013-1081 cm-1, indicating the presence of compounds containing Si-O or Si-O-R groups in oleoresin. Our results suggest that the oleoresin contains a substantial amount of dispersed biosilica and/or several organosilicon compounds, not reported till date.
 
“Spooky” interaction and non-classical interference interpreted by a product of classical electric field
Get PDFMany experiments to verify nonlocal interaction and non-classical phenomena using entangled lights were conducted in the 1980s, and many physicists were interested in their unrecognizable correlation. These quantum mechanical effects were used in Aspect\u27s experiments and Bell tests and had a great influence on the interpretation of quantum mechanics. However, their essence, including their “spooky” interaction, is unknown. In this study, we show that entangled light can be expressed by the product of electric fields and that the same result as quantum mechanics can be obtained using the product form
Predicting the Fate of Schrodinger’s Cat
Get PDFWe describe a simple experiment in which a radioactive atom in a box decays in unit time with probability equal to ½, but such that the probability of a correct prediction of whether or not the atom decays is greater than ½
Experimental verification of wave packet collapse using fourth-order interference
Get PDFThe concept of wave packet collapse is the most interesting and difficult to understand assumption of quantum mechanics and it remains an unresolved issue. Therefore, it is necessary to carefully examine its principle and process experimentally. We fabricated a new fourth-order interference apparatus capable of verifying the collapse of a wave packet. Contrary to expectation, a “collapse” was not observed in our experiment
A Semiclassical Model of Leptons
Get PDFA semi-classical model of leptons is presented on the assumption that they are stable equilibrium states of spherical bubble like extended structures with negative pressure of a false vacuum created inside and balanced by an outward stress due to vacuum polarization originating from the charge residing on the surface. The idea is a semiclassical analog of the Poincare model of the electron, where the outward classical electromagnetic stress is replaced by the stress due to vacuum polarization. Here the electron carries a bare mass (energy) due to negative pressure or equivalently a positive energy density inside and QED electromagnetic self-energy and both dependent on a cut-off radius R. Minimization of total energy with respect to R, yields a relation connecting equilibrium radius, negative pressure P, renormalized fine structure constant and lepton mass. Assumption that the maximum possible value of P corresponds most massive tau lepton is Planck pressure, enables determination of the renormalized fine structure constant and input of masses of the electron and muon determines corresponding internal negatives pressures and lepton radii. Tau lepton size is of the order of the Planck length and the muon and the electron are two and three orders of magnitude larger. Model suggests that the lepton flavor is an attribute associated with three different phases of a false vacuum
Omnidirectional reflection band in multi-layered graphite film based one dimensional photonic crystal nanostructure
Get PDFWe report the omnidirectional reflection (ODR) in one dimensional photonic crystal (PC) structure consisting of alternate layers of Graphite as material of low refractive index and Tellurium (Te) as material of high refractive index. The effects of the incidence angles on the spectral reflectance have been investigated using transfer matrix method (TMM). The proposed structure gives 100% reflection within a wide range of wavelengths in the visible-near IR region and can be used effectively in wavelength filters, optical resonators and mirrors for visible-near IR region of electromagnetic spectrum. Due to considerable control of absorption of low frequency radiation in graphite, the damping and skin effect in the PC are also suppressed. The investigation has also been made for the study of role of ambient medium and the effect of number of layers in formation of ODR
Anisotropic bulk viscous string cosmological models with heat flux
Get PDFBulk viscosity coupled with cosmic string for Bianchi type VI0 cosmological model is investigated in the context of Self creation theory of gravitation. Field equations are solved for two different cases by considering relation between metric potentials. It is assumed that scalar function is proportional to the scale factor. It is found that the universe is anisotropic and stable. The early universe is highly heated. Some physical parameters are also discussed in details
Enhancement of omnidirectional bandgap in graphene based quasi-periodic one dimensional photonic crystal heterostructures
Get PDFWe study the omnidirectional reflection (ODR) in one dimensional photonic crystal (PC) structures consisting of alternate layers of graphene as material of high refractive index and SiO2 as material of low refractive index. The effects of the thickness of layers and incidence angles on the spectral reflectance have been investigated using transfer matrix method (TMM). The proposed structure gives high reflection within a wide range of wavelengths in the visible and near infrared region and can be used effectively in wavelength filters, optical resonators and mirrors. We also propose here the considerable enhancement of omnidirectional reflection band in near infrared region by changing the design parameters using a gradual constant. Due to considerable control of absorption and small dissipation of electromagnetic energy in graphene, the damping and skin effect in the PC are also obscured
The Effect of Doping Concentrations on the Thickness of the Depletion Layer on Some Semiconductor Materials
Get PDFIn this work, the code “Poisson” written by Silsbee and Drager, developed at Cornell University was used to Simulate band bending and carrier concentrations in the inhomogenous semiconductors: Gallium nitride, Zinc oxide, Cadmium sulfide, Cadmium selenide, Cadmium telluride, Indium phosphide, Gallium arsenide and Silicon. The energy gap for these semiconductors is generally greater than 1eV. Simulation of doping concentrations was run on preset four (4) on the code “Poisson”. The effect of doping concentrations on the thickness of the depletion layer width and charge displacement of the semiconductor materials was obtained. The width of depletion layer decreases with increase in doping concentrations while increase in doping concentrations leads to increase in the charge displacement. The relationship between depletion layer width and the doping concentrations (from 1×1020 to 1×1016 cm-3 ) is best described by a power function of the form y=axb. On the other hand, wide band gap results in increase in depletion layer width