Jean Marie NDJAKA

Highlighting some layers properties in performances optimization of CIGSe based solar cells: Case of Cu(In, Ga)Se–ZnS

Tchangnwa Nya Fridolin, Dzifack Kenfack Guy Maurel, Geh Wilson Ejuh, Touogam Touolak Bénédicte, Ndjaka Jean Marie

Journal of King Saud University - Science

In this research work which is based on recent studies, we investigated the effects of the physical properties of the Zinc Sulfide (ZnS) buffer layer such as electronic affinity, doping concentration and thickness on the electrical parameters of a defined solar cell structure. These properties values, combined with those of the CIGSe absorber layer and other materials that make up our cell, provide vital information on the optimization of the layer properties that enhance the efficiency of the CIGSe based ultra-thin solar cells. After a judicious choice of the input parameters of the materials constituting our solar cell device, we obtained employing SCAPS numerical simulation software, electrical parameters more interesting than those found in the literature. In particular, for 5 nm thickness of the ZnS buffer layer and 500 nm thickness of the CuIn0.7Ga0.3Se2 absorber layer, we obtained an efficiency η = 21.42% and a fill factor FF = 82.16%. For 5 nm thickness of the ZnS buffer layer and 2500 nm thickness of the CuIn0.7Ga0.3Se2 absorber layer, we obtain an efficiency η = 26.30% and a fill factor FF = 85.15% with a good choice of others material properties such as intrinsic doping concentration, electrons and holes mobility. A good knowledge of the exact parameters of simulations, allowed us to determine the values of the optimal properties of the Cu(In, Ga)Se–ZnS solar cell, useful for their physical implementation.

• #chalcogenide semiconductor thin films
• #quantum dots synthesis and properties
• #copper-based nanomaterials and applications
• #zinc sulfide

Computational determination of the Electronic and Nonlinear Optical properties of the molecules 2-(4-aminophenyl) Quinoline, 4-(4-aminophenyl) Quinoline, Anthracene, Anthraquinone and Phenanthrene

Geh Wilson Ejuh, Nouemo Samuel, Tchangnwa Nya Fridolin, Ndjaka Jean Marie

Materials Letters

• #nonlinear optical materials research
• #photochemistry and electron transfer studies
• #synthesis and properties of aromatic compounds
• #anthracene

Modeling of the electronic, optoelectronics, photonic and thermodynamics properties of 1,4-bis(3-carboxyl-3-oxo-prop-1-enyl) benzene molecule

Geh Wilson Ejuh, Nouemo Samuel, Fridolin Tchangnwa Nya, Ndjaka Jean Marie

Journal of the Iranian Chemical Society

• #nonlinear optical materials research
• #synthesis and properties of aromatic compounds
• #organic chemistry cycloaddition reactions
• #hyperpolarizability

Vibrational Spectra, Electronic Structure and Properties of the Molecules Aspirin and Ibuprofen.

Geh Wilson Ejuh, Chifu E. Ndikilar, Fridolin Tchangnwa Nya, Nouemo Samuel, Ndjaka Jean Marie

JOURNAL OF ADVANCES IN PHYSICS

The FT-IR Vibrational spectra analysis, electronic structures and properties of the anti-inflammatory drugs Aspirin and Ibuprofen in gas and water and ethanol have been studied by using ab initio and DFT computational calculation. The present investigation deals with the analysis of structural and bonding features responsible for biological activities, stability of the molecules, average polarizability, anisotropy, energies and the IR vibrational spectra of the molecules. The observed and the calculated vibrational frequencies are found to be in good agreement. The experimental FT-IR spectra also coincide satisfactorily with those of the theoretically constructed line spectra at the B3LYp/6-31+G* level of theory.

• #nonlinear optical materials research
• #free radicals and antioxidants
• #organic chemistry cycloaddition reactions
• #molecule

Linear and Non Linear Optical Effects of Pyrimethamine and Sulfadoxine: Ab-initio and Density Functional Study

Geh Wilson Ejuh, Ndjaka Jean Marie

˜The œAfrican review of physics

The molecular structures of pyrimethamine and sulfadoxine have been explored for non linear optical ef fects. The abinitio Hartee Fock calculations and Density Functio nal Theory with B3LYP method have been carried out employing 6311++G** basis set. The dipole moments ( µ), polarizability ( α), and first hyperpolarizability ( βmol ) in gas phase and in solvated medium (water and ethanol) are calculated using the same level of theory. The variation of th e C-N bond lengths suggests that there is an extended pi-electron delo calization over the pyrimidine moiety that is respo nsible for non linearity of these molecules. Equally, the large values of βmol for these molecules suggest potential applications of these molecular systems in the development of non linear materials. The large βmol values, which is a measure of the non linear optical activity of the molecular system, is associated wit h the intermolecular charge transfer resulting from an electron cloud movement through the pi-electron delocalization. Hence theoretical determination of βmol is quite useful, both in the understanding of relationship between the molecular structure and non linear optical properties.

• #nonlinear optical materials research
• #molecular spectroscopy and chirality
• #spectroscopy and quantum chemical studies
• #polarizability

A Study of Structure and Thermo-dynamical Properties of Pyrimethamine Obtained by an Analytical Hessian Calculation

Geh Wilson Ejuh, Ndjaka Jean Marie, Amar Singh

˜The œAfrican review of physics

Molecular modeling of the structure of Pyrimethamine molecule has been carried out in an attempt to un derstand its structure and thermo-dynamical properties using the Hessian matrix. Ab initio and DFT geometric optimizations were carried out at RHF/6-311++G** and B3Lyp/6-311++G** level of theory in the gas medium. The zero point vibrationa l energy (ZPVE), enthalpy (H), entropy (S) and relative free energy (G) have been calculated from the frequenci es obtained by an analytical Hessian calculation. The polarizability tensor components, the average polarizability and t he anisotropy have also been calculated. The theoretical calculation shows that B3LYP/6-311++G** values were higher than the RHF/6-311, a result we believe is due to the effect of electron correla tion.

• #advanced physical and chemical molecular interactions
• #various chemistry research topics
• #chemical thermodynamics and molecular structure
• #hessian matrix