Browsing by Author "Mbese, Johannes Z. 0000-0001-9136-9302"

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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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    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%.