Browsing by Author "Meyer, Edson L."

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    Advances in the Use of Atomic Force Microscopy as a Diagnostic Tool for Solar Cells Characterization: From Material Design to Device Applications
    (Wiley, 2023-12-03) Ahia, Chinedu Christian; Meyer, Edson L.
    Considerable efforts in search for an effective characterization technique for photovoltaic devices with utmost precision is on the increase. For precise analysis and tailoring of device performance, a reliable technique is vital. Atomic force microscopy is one of the leading surface analysis techniques of choice for probing surface patterns in a variety of materials with atomic precision using a cantilever. It has evolved as a reliable technique for the investigation of subatomic scale properties of materials such as photocurrent heterogeneity, electromechanical response, charge distribution, molecular weight effects, and many other material parameters. The integration of artificial intelligence hybrid algorithms in atomic force microscope for optoelectronic device fabrication and characterization has increasingly emerged to be desirable due to its reliability and effectiveness in achieving high image resolution, automated analysis, actuation, and the coupling of manufactured units with a precision down to atomic units. In this review, an investigation of topical developments in the use of atomic force microscopy as a diagnostic tool for solar cells characterization is presented with special focus on polymer solar cells, perovskite solar cells, quantum dots-sensitized solar cells, dye-sensitized solar cells, fullerene-based solar cells, III-V-based solar cells, and silicon-based solar cells.
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    Development of cupric sulphate nanocrystals on fluorine-doped tin oxide substrates using hydrothermal technique
    (Springer, 2023-06-29) Ahia, Chinedu Christian; Meyer, Edson L.
    Cupric sulphate nanocrystals (NCs) are desirable for a number of applications. The NCs were grown using a hydrothermal technique on Fluorine-doped Tin Oxide substrate which was sandwiched into the grooves of a sample holder at an angle between 45 and 90 relative to the wall of a 100 ml Teflon container. The surface features were observed using an optical microscope while atomic scale features which are not visible under the optical microscope were investigated using a scanning electron microscope and atomic force microscope. Details of the weight percentage composition were investigated on the sample by means of energy-dispersive X-ray spectroscopy. A broad absorption spectrum from 690 to 1100 nm, having a full width at half maximum value of 254 nm and an energy excitonic absorption peak in the visible region at 810 nm, was observed when the NCs are dissolved in water (hydrate solution) contrary to the highest absorption peak which was observed at 678 nm for the anhydrous compound. A total number of 16 vibrational frequencies were observed from Raman scattering while five active modes were visible in the Fourier Transform Infrared spectrum. Information on room-temperature photoluminescence and fluorescence spectroscopy measurements obtained from the NCs is reported. The deposition technique adopted in present work could be optimized for the high-yield production of more uniform layers of ultrathin nanostructures with increased aptitude for various applications.
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    Influence of a One-Pot Approach on a Prepared CuS Macro/Nanostructure from Various Molecular Precursors
    (MDPI, 2023-06-24) Agoro, Mojeed A.; Meyer, Edson L.; Gulino, A.
    Nanostructured metal sulfides such as copper sulfide (CUS) form from single-source precursors (SSPs) and are cost-friendly materials that can be used in a one-pot approach with potential applications in dye-sensitizer solar cells (DSCs). This is an attractive pathway that allows the careful control of tailoring the design of the nanostructures with slight variations in the mixture conditions to form uniform nanoparticles and enhance the performance of DSCs. We report on the optical, structural, and morphological properties of CuS as photosensitizers and their application in QDSCs using characterization techniques such as cyclic voltammetry (CV), current–voltage (I-V), UV-Vis spectroscopy (UV-Vis), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), etc. The UV-Vis reveals that the band gap for the three samples is found at 2.05–2.87 eV, confirming them as suitable materials for solar cells. The XRD peaks for the three CuS nanoparticles harmonized very well with hexagonal CuS. The thermal gravimetric (TGA) suitability of the three complexes shows a two-step decomposition within the temperature range of 125–716 ◦C, with a final residue of 2–4%. CV curves for three samples show that none of the developed metal sulfides exhibits a peak indicative of limited catalytic activity in the iodine electrolyte. The I-V overall energy conversion efficiency (η%) of 4.63% for the CuSb photosensitizer is linked to the wide electronic absorption spectrum and better relative dye loading. The synthesis of photosensitizers from a trioctylphosphine oxide (TOPO) capping agent shows improved efficiency compared to our previous studies, which used hexadecylamine as a coordinating solvent.