Browsing by Author "Meyer, Edson L. 0000-0002-9912-311X"

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    Aliphatic mixed ligands Sn(II) complexes as photon absorbers in quantum dots sensitized solar cell
    (Elsevier, 2022-04) Agoro, Mojeed A. 0000-0002-0434-9635; Meyer, Edson L. 0000-0002-9912-311X; Mbese, Johannes Z. 0000-0001-9136-9302; Fuku, Xolile 0000-0001-8247-109X; Ahia, Chinedu C. 0000-0002-5666-1823
    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.
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    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. 0000-0002-0434-9635; Mbese, Johannes Z. 0000-0001-9136-9302; Meyer, Edson L. 0000-0002-9912-311X; Onyenankeya, Kevin 0000-0001-5814-8823
    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.
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    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 0000-0002-0434-9635; Meyer, Edson L. 0000-0002-9912-311X
    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.
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    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. 0000-0002-0434-9635; Mbese, Johannes Z. 0000-0001-9136-9302; Meyer, Edson L. 0000-0002-9912-311X
    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%.
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    Proficient One-Step Heat-Up Synthesis of Manganese Sulfide Quantum Dots for Solar Cell Applications
    (MDPI, 2022-10-07) Agoro, Mojeed A 0000-0002-0434-9635; Meyer, Edson L. 0000-0002-9912-311X
    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.
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    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. 0000-0002-0434-9635; Meyer, Edson L. 0000-0002-9912-311X
    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.