Department of Physics & Materials Science: Recent submissions
Now showing items 41-60 of 158
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Occurrence characteristics of equatorial plasma bubbles over Kisumu, Kenya during Solar maximum of Solar Cycle 24
(International Journal of Advanced Astronomy, 2021)Equatorial Plasma Bubbles (EPBs) are irregular plasma density depletions in the ambient electron density in the equatorial F-region ion osphere generated after sunset. EPBs are known to bring disruptions to telecommunication ... -
Conserved excitation number and U(1)-symmetry operators for the anti-rotating (anti-Jaynes-Cummings) term of the Rabi Hamiltonian
(Cornell University, 2021)In this article we apply algebraic operator ordering property of the basic atom and field operators to construct and prove conservation of the excitation number operator of the anti-rotating (anti-Jaynes-Cummings) component ... -
The anti-Jaynes-Cummings model is solvable : quantum Rabi model in rotating and counter-rotating frames ; following the experiments
(Cornell University, 2021)This article is a response to the continued assumption, cited even in reports and reviews of recent experimental breakthroughs and advances in theoretical methods, that the antiJaynes-Cummings (AJC) interaction is an ... -
Symmetry conjugates and dynamical properties of the quantum Rabi model
(Cornell University, 2021)Symmetry transformations have proved useful in determining the algebraic structure and internal dynamical properties of physical systems. In the quantum Rabi model, invariance under parity symmetry transformation has been ... -
Enhancing light absorption and lifetime stability of organic solar cells using pentacene encapsulation
(SA Institute of Physics, 2015). In the present work we compare the performance of a pristine P3HT:PCBM based bulk heterojunction solar cell with a device incorporated with pentacene encapsulated Ag nanoparticles. Encapsulation has been achieved through ... -
Improved efficiency of organic solar cells using Au NPs incorporated into PEDOT: PSS buffer layer
(AIP Publishing LLC, 2017)Au based plasmonic phenomenon inside the hole transport layer poly(3,4- ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) of an organic solar cell based on blend of poly(3-hexylthiophene) (P3HT) and [6:6]-phen ... -
Structural and spectroscopic analysis of ex-situ annealed RF sputtered aluminium doped zinc oxide thin films
(AIP Publishing LLC, 2017)Aluminium doped zinc oxide thin films are prepared by Radio Frequency magnetron sputtering in pure argon atmosphere at 100 W. The structural results reveal good film adhesion on a silicon substrate (001). The thin films ... -
[HTML] from rsc.org Effect of thermal treatment on ZnO: Tb 3+ nano-crystalline thin films and application for spectral conversion in inverted organic solar cells
(Royal Society of Chemistry, 2018)Down conversion has been applied to minimize thermalization losses in photovoltaic devices. In this study, terbium-doped ZnO (ZnO:Tb3+) thin films were deposited on ITO-coated glass, quartz and silicon substrates using ... -
Role of oxygen concentrations on structural and optical properties of RF magnetron sputtered ZnO thin films
(Springer US, 2019)We report an investigation on the efect of oxygen fow rate on the structural and optical properties of zinc oxide thin flms prepared by RF magnetron sputtering. The structural measurements were carried using grazing ... -
Probing the stoichiometry dependent catalytic activity of nickel selenide counter electrodes in the redox reaction of iodide/triiodide electrolyte in dye sensitized solar cells
(Royal Society of Chemistry, 2020)Nickel selenide (NixSey) systems have received much attention in recent years as potential low cost counter electrodes (CEs) in dye sensitized solar cells (DSSCs). Their electrocatalytic activities are comparable to ... -
Annealing efect on the structural and optical behavior of ZnO:Eu3+ thin flm grown using RF magnetron sputtering technique and application to dye sensitized solar cells
(Nature Publishing Group, 2020)Eu-doped ZnO (ZnO:Eu3+) thin flms deposited by RF magnetron sputtering have been investigated to establish the efect of annealing on the red photoluminescence. PL spectra analysis reveal a correlation between the ... -
The effect of temperature and time on the properties of 2D Cs 2 ZnBr 4 perovskite nanocrystals and their application in a Schottky barrier device
(Royal Society of Chemistry, 2021)2D hybrid perovskites are promising materials for solar cell applications, in particular, cesium-based perovskite nanocrystals as they offer the stability that is absent in organic–inorganic perovskites. However, the most ... -
Comparative Investigation of Fullerene PC 71 BM and Non-fullerene ITIC-Th Acceptors Blended With P3HT or PBDB-T Donor Polymers for PV Applications
(Frontiers, 2021)Fundamentally, organic solar cells (OSCs) with a bulk-heterojunction active layer are made of at least two electronically dissimilar molecules, in which photoabsorption in one (donor) generates Frenkel excitons. The ... -
Enhancing climate action at grassroots levels in least developed countries: unlocking bio-briquetting opportunities for communities in Wajir, Vihiga, Kitui, and Kajiado counties in Kenya
(Inderscience Publishers (IEL), 2021)Grassroots communities are often the hardest hit by climate change. They also appreciably contribute to the problem through activities like deforestation, land use changes, and cooking with firewood. Bio-briquettes from ... -
Evaluating the effect of the substrate on the electrocatalytic performance of Cu2ZnSnS4 and Cu2ZnSnSe4 counter electrodes in dye-sensitized solar cells
(Elsevier, 2022)The colloidal synthesis of Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) nanoparticles and their application as counter electrodes in dye-sensitized solar cells (DSSCs). In particular, the effect of three substrates namely; ... -
Microstructural and elastic properties of stable aluminium-rich TiAl and TiAl2 formed phase Intermetallics
(North-Holland, 2021)We studied aluminium-rich Ti-Al (Ti32Al68 and Ti40Al60) binary alloys that were composed of TiAl and TiAl2 lamellar microstructures. The law of mixtures was employed in calculating the theoretical Young’s moduli. The ... -
Optical properties and Raman studies of amorphous se-bi thin films
(The African Review of Physics, 2014)Flash evaporated amorphous Se Bi (x = 0, 1, 2, 3, and 4 at. %) thin films of 350 ± 10 thickness have been investigated in the wavelength range of 200nm − 3000nm. It is found that the effect of increasing bismuth content ... -
Investigation of the effect of film thickness on the optical properties of amorphous Se85-xte15sbx thin films
(Africa Journal of Physical Sciences, 2014)Amorphous thin films of Se85-xTe15Sbx (x = 0.0, 0.5, 2.5, and 5.0 at. %) deposited by flash evaporation technique, have been investigated in the wavelength range of 500nm-3000nm. It is found that the effect of increasing ... -
Compositional and Thickness Effects on the Optical Properties of Zinc– Doped Selenium–Antimony Thin Films
(AJOL, 2018)Chalcogenide system of antimony (Sb)-selenium (Se)-zinc (Zn) system is a promising semiconductor for phase change memory devices due to its thermal stability and low power consumption. The study investigated the effect ... -
Investigation of long acoustic waveguides for the very low frequency characterization of monolayer and stratified air-saturated poroelastic materials
(Elsevier, 2021)When sound propagates in a porous medium, it is attenuated via several energy loss mechanisms which are switched on or off as the excitation frequency varies. The classical way of measuring acoustic energy loss in porous ...