OAJ Materials and Devices

Effect of RGPP (Reactive Gas Pulsing Process) deposition parameters on physical properties and electrochromic performances of WOx thin films

2025-11-19T10:46:57+00:00

WO_x electrochromic films were deposited using an innovative method known as RGPP (Reactive Gas Pulsing Process) by varying the parameter t_ON which controls
the duration of oxygen pulsing. This parameter has little influence on the chemical composition and physical properties but significantly affects their electrochromic performance, particularly the discoloration time and coloration efficiency. The deposited films are sub-stoichiometric (WO?.?? – WO?.??) and transparent, with a refractive index ranging from 2.11 to 2.12 and a porosity from 15% to 16% as t_ON increases from 10 s to 40 s. The ion density and defects in the films vary slightly. The coloration times of films are very similar (12 s - 13 s), whereas the discoloration time varies significantly, from 71 s to 275 s for t_ON = 10 s to 40 s, respectively. The highest CE = 50 cm²/C was obtained for the film deposited with t_ON = 30 s.

A Effect of Annealing on Physicochemical, Optoelectronic and Gas Sensing Properties of Polyaniline Thin Films

2025-04-16T18:04:54+00:00

The present article describes about synthesis of polyaniline thin films by soft chemical solution polymerization method at room temperature over glass substrate and effect of air annealing at 100, 200 and 300^oC on the physicochemical and optoelectronic properties intending to characterize as gas sensing materials. The as deposited and annealed thin films characterized for compositional, elemental, surface morphology, optical properties and electrical properties along with ammonia gas sensing applications. Slight shift in peaks positions from 1167, 1372, 1506 and 1593 cm^-1 and broadening of peak with increase in intensity recorded on Fourier transform infra-red (FTIR) spectra confirm annealing induced elemental variations, while Raman spectrum represents chemical bond shifting upon annealing polyaniline thin films which can be inferred as compositional modifications upon annealing. Fatty granular appearing surface morphology obtained in atomic force microscopy (AFM) found to be coalesces into smaller granular shapes on post deposition treatments which can also be confirmed from the scanning electron microscopy (SEM) images. Optical absorbance shows shift in absorbance peaks corresponding for excitation of polaron band which observed to be red shifted may be correlated to polygonization process i.e. absorbance of energy at the surface and utilizing in materials modifications. The ammonia gas sensing characteristics have represented the increase in gas response upto 85% for the sample annealed at 200^oC The response and recovery time is observed to be lower than the as deposited and 300C annealed samples, this can be correlated to the fact of structural saturations at moderate annealing.

Neighborhood Degree-Based Topological Indices of chemical structure of Conductive 2D Metal-Organic Framework

2025-04-23T12:55:18+00:00

The conductive 2D metal-organic framework (MOF) $Cu_3(HITP)_2[s, t]$ exhibits remarkable electronic properties due to its highly ordered structure and efficient charge transport, making it a promising material for applications in electronics and energy storage. A topological index is a numerical value derived from the structure of a molecular graph, used to describe its topology and predict chemical, physical, or biological properties. This study explores the topological properties of 2D MOF $Cu_3(HITP)_2[s, t]$ using neighborhood degree-based indices. We compute NM-polynomials for this chemical structure, facilitating the derivation of various neighborhood degree-based indices through advanced algebraic and calculus-based methods. These indices are crucial in understanding the structural characteristics and electronic properties of the materials.

Abstract book ISPESFM

2025-11-23T20:06:08+00:00

This volume compiles the proceedings of the first International Symposium on Physics of Energy Storage and Ferroic Materials (ISPESFM), held in October 2024 in Abidjan, Ivory Coast. It highlights innovative research on renewable energy sources, ferroic materials, and energy storage and conversion technologies. The contributions focus on the development of solar, wind, hydro, and biomass energies, as well as the application of ferroelectric, piezoelectric, and smart materials for sustainable energy solutions. The primary goal is to promote scientific advancements to support the energy transition, emphasizing Africa’s abundant natural resources and the importance of strengthening research and innovation on the continent. This collection provides a platform for sharing knowledge and fostering collaboration toward a future of environmentally sustainable and resilient energy systems.

Studying the confined membrane bundle by solving the Schrödinger-like equation using the Bethe ansatz method

2025-04-03T15:15:38+00:00

Elastic membranes stretched between two substrates adopt shapes determined by their separation length. This behaviour is analogous to many biological structures, such as coiled DNA and mitochondria in eukaryotic cells. Such systems can be modelled as a stack of parallel membranes separated by layers of water. In this study, we focus on a simplified system of four membranes, where the upper and lower membranes are modelled as two rigid walls. The two-dimensional shapes of the elastic membranes confined between these walls are investigated by introducing the Morse Double Potential (MDP). In the first step, we established a Schrödinger-like equation within the continuum limit approximation. Solving this equation allowed us to distinguish between the excited states and the fundamental (ground) state. Our results demonstrate that the shape of the substrate potential plays a crucial role in determining both the membrane's unbinding transition temperature and the separation length between the two confined membranes.

Optical and Electrophysical Properties of the Germanium Oxynitride-Semiconductor Structure

2025-04-03T15:13:03+00:00

The paper studies the optical and electrophysical characteristics of dielectric films of germanium oxynitride obtained by nitridation of single-crystalline germanium with humid ammonia and deposition of reaction products on semiconductor substrates. These films create a high-quality interface with silicon and indium phosphide.

Improvement of the quality of short-term forecast of the solar potential using hybrid model: application to Dakar region

2025-11-24T16:53:18+00:00

This study addresses the critical need to enhance short-term forecasting of solar potential for photovoltaic
power generation in Senegal, focusing on the Dakar region. A hybrid forecasting model is developed by integrating
a Gaussian Mixture Model (GMM), a Hidden Markov Model (HMM), and a Kalman Filter (KF) to characterize the
variability of solar radiation influenced by meteorological factors. The GMM identifies distinct fluctuation states of
solar radiation using the EM algorithm, while the HMM captures temporal dependencies between these states
through Forward Backward and Viterbi algorithms. Subsequently, a Kalman Filter refines state-based predictions
within a 20-minute horizon. Comparative results demonstrate that the hybrid model [NRMSE=0.0093,
NMAE=0.044 and NMBE=0.0006] significantly outperforms the standalone Kalman Filter [NRMSE =0.048,
MBE=2.718 and NMAE=0.004] 0.004], achieving lower normalized root mean square errors and bias metrics. This
innovative approach offers a robust probabilistic and deterministic framework to improve intermittent solar energy
forecasting, supporting optimized energy planning in the Sahelian zone.