DSpace Repository :: Browsing by Author "Meyer, Edson L."

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.
Aliphatic mixed ligands Sn(II) complexes as photon absorbers in quantum dots sensitized solar cell
(Elsevier, 2022-04) Agoro, Mojeed A. ; Meyer, Edson L. ; Mbese, Johannes Z. ; Fuku, Xolile ; Ahia, Chinedu C.
Dye-sensitized solar cells have attracted a lot of research interest due to the quest for an alternative energy supply given that it is cost-effective and its materials are easily available. However, the need to improve the conversion efficiency of these solar cell devices has necessitated the search for new materials that will lead to more energy conversion. One of such material of interest is tin (II) sulfide (SnS). In present study, we report results from the synthesis of hexadecylamine (HDA)-capped SnS and uncapped SnS photosensitizer using a molecular precursor. The efficiency of the photon absorbers, their morphological, structural and electrochemical properties were examined using different techniques. Both photosensitizers displayed X-ray diffraction (XRD) peaks within the range 26.03 –66.05 , which corresponds to orthorhombic structure. Field Emission Scanning Electron Microscope (FE-SEM) and High-Resolution Transmission Electron Microscope (HRTEM) further revealed that HDA-capped SnS has a better morphology and size distribution. UV–Vis analysis shows that the HDA-capped SnS exhibits strong absorption in the entire visible region which is attributed to perfect orientation. The HDA-capped photosensitizer superiority was linked to well reduced electron recombination and electron lifetime. The addition of HDA capping agent improved the J-V performance with a new conversion efficiency of 8.20%. Results obtained from present work proselytize the concept of using capping agent as an approach for improving the quality of photon absorbers.
Chalcogenide Perovskites and Perovskite-Based Chalcohalide as Photoabsorbers: A Study of Their Properties, and Potential Photovoltaic Applications
(MDPI, 2021-12-18) Adjogri, Shadrack. J. ; Meyer, Edson L.
In 2015, a class of unconventional semiconductors, Chalcogenide perovskites, remained projected as possible solar cell materials. The MAPbI3 hybrid lead iodide perovskite has been considered the best so far, and due to its toxicity, the search for potential alternatives was important. As a result, chalcogenide perovskites and perovskite-based chalcohalide have recently been considered options and potential thin-film light absorbers for photovoltaic applications. For the synthesis of novel hybrid perovskites, dimensionality tailoring and compositional substitution methods have been used widely. The study focuses on the optoelectronic properties of chalcogenide perovskites and perovskite-based chalcohalide as possibilities for future photovoltaic applications.
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.
Electrochemical signature of CuS photosensitizers thermalized from alkyldithiocarbamato Cu(II) molecular precursors for quantum dots sensitized solar cells
(Elsevier, 2020-12-10) Agoro, Mojeed A. ; Mbese, Johannes Z. ; Meyer, Edson L. ; Onyenankeya, Kevin
Environmental friendly and affordable energy sources is one of the biggest challenges of modern society. The substantial negative impact of fossil fuels on the environment has prompted the need for clean and sustainable solar energy. Recent reports affirm that increase in photovoltaic conversion efficiency is directly linked to morphology control resulting in excellent catalytic activity on the active layer. Herein, we report on the fabrication of (H is the addition of hexadecylamine HDA capping agents CuSH) and (CuS without HDA) photosensitizers using molecular precursor approach. The obtained CuS-H and CuS were characterized using structural, morphological and electrochemical instruments. The CV, EIS and bode plot results show that CuS displayed stronger electrocatalytic activity as a good optimum sensitizer. J-V efficiency obtained indicates that the CuS exhibited a much better efficiency in the QDSCs compared to CuS-H.
FeS/FeS2 nanoscale structures synthesized in one step from Fe(ll) dithiocarbamate complexes as a single source precursor
(Frontiers, 2022-12-02) Agoro, Mojeed A ; Meyer, Edson L.
Nanoscale FeS and FeS2 mixed phases were synthesized by one-pot decomposition of (N-anil-N-piperldtc)Fe1 as FeS#1), (N-piperldtc)Fe2 as FeS#2) and (N-anildtc)Fe3 as FeS#3) complexes as precursors, with the help of tri-n-octylphosphine oxide (TOPO) coordinating solvent. Their morphology, stability, size, optical and structural characteristics were observed using various material characterization instruments. In comparison to the FeS#2 nano-flower shape, FeS#1 and FeS#3 have a uniform nano-rod shape. A one-step decomposition pattern was obtained from the thermal gravimetric analysis (TGA) results with 3% final mass residual. The high-resolution transmission electron microscopy (HRTEM) image reveals an aggregation and size diameter of around 14.47–30.25 nm for the three samples. The optical response between 3.8 and 4.2 eV from the three samples shows that they are inconsiderable materials for solar cells application. The diffraction peaks for the three samples matched well with the FeS/FeS2. These nanoscale materials can be used in a variety of applications, including lithium-ion batteries, biosensors, hydrogen evolution, and multifunctional nanocomposite materials.
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.
Inorganic Pb(II)−P and Pb(II)−S Complexes as Photosensitizers from Primary and Secondary Amines in Dyes-Sensitized Solar Cells
(American Chemical Society, 2021-09-03) Agoro, Mojeed A. ; Mbese, Johannes Z. ; Meyer, Edson L.
Pb(II) complexes of bis(N-1,4-phenyl-N-(4-morpholinedithiocarbamato)) as Pb(II)−S and bis(N-diisopropyl-Noctyldithiocarbamato) as Pb(II)−P were prepared and characterized by optical, structural, morphological, and electrochemical techniques. The scanning electron microscopy analysis of Pb(II)−P and Pb(II)−S complexes consists of cubic crystals. X-ray diffraction and high-resolution transmission electron microscopy spectral studies revealed that the diameter increases in length for alkyl chain groups. This study demonstrates that the cubic shape of Pb(II) complexes can be synthesized from aromatic and aliphatic dithiocarbamate ligands. Photoluminescence analysis of both complexes fell within the blue shift region. The CV curve for Pb(II)−S revealed redox curves and the box-like shape as an indicative of a capacitive behavior, signifying limited catalytic redox activity. The J−V results for both sensitizers displayed satisfactory conversion efficiency (% η) between 3.77 and 3.96%.
Proficient One-Step Heat-Up Synthesis of Manganese Sulfide Quantum Dots for Solar Cell Applications
(MDPI, 2022-10-07) Agoro, Mojeed A ; Meyer, Edson L.
The necessity to develop renewable energy resources that are highly durable and flexible with superior energy density and capacitance ability has attracted considerable interest in the field of solar cell research. Semiconducting compound materials that are easily available, hazard-free and cost-effective are emerging as potential solutions to tackle this challenge. Herein, we present multiple molecular precursors used to grow manganese sulfide nanoparticles through a proficient one-step heat-up approach. For all of the tested samples, the X-ray diffraction peaks correspond to a γ-MnS hexagonal wurtzite structure. UV-Vis spectroscopy yielded absorption wavelengths of 359–420 nm and band-gap energies of 3.78–4.0 eV. Photoluminescence analysis shows characteristics of red and blue shift from 451–602 nm. High-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED) reveal a narrow size distribution with nanosticks and large contact areas, which are critical for improved catalytic performance. The current study provides an improved pathway to a well-grown and uniform nanocrystal structure for applications in energy devices.
Roles of TOPO Coordinating Solvent on Prepared Nano-Flower/Star and Nano-Rods Nickel Sulphides for Solar Cells Applications
(MDPI, 2022-09-28) Agoro, Mojeed A. ; Meyer, Edson L.
The present study describes a cheap, safe, and stable chemical process for the formationof nickel sulphide (NiS) with the use of mixed and single molecular precursors. The productionpathway is uncomplicated, energy-efficient, quick, and toxic-free, with large-scale commercialization potential. The obtained results show the effect of tri-N-octylphosphine oxide (TOPO) as a coordinating solvent on the reaction chemistry, size distributions, morphology, and optical properties of both precursors. Ni[N,N-benz-N-p-anisldtc] as NiSa, Ni[N,N-benzldtc] as NiSb, and Ni[N-p-anisldtc] as NiSc thermally decompose in a single step at 333–334 ◦C. The X-ray diffraction peaks for NiSa, NiSb, and NiSc matched well with the cubic NiS nanoparticles and corresponded to planes of (111), (220), and (311). The extrapolated linear part from the Tauc plots reveals band gap values of 3.12 eV, 2.95 eV, and 2.5 eV, which confirms the three samples as potential materials for solar cell applications. The transmission electron microscopy (TEM) technique affirmed the quantum dot size distribution at 19.69–28.19 nm for NISa, 9.08–16.63 nm for NISb, and 9.37–10.49 nm for NISc, respectively. NiSa and NiSc show a clearly distinguishable flower/star like morphology, while NiSb displays a compact nano-rod shape. To the best of the authors’ knowledge, very few studies have been reported on the flower/star like and nano-rod shapes, but none with the dithiocarbamate molecular precursor for NiS nanoparticles.

Browsing by Author "Meyer, Edson L."

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