Browsing by Author "Mageto, Maxwell"

Now showing 1 - 6 of 6
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    Publication
    Acoustical properties of compressed earth blocks: Effect of compaction pressure, water hyacinth ash and lime
    (Elsevier, 2023-07-01) Ouma, Justus; Ongwen, Nicholas; Ogam, Erick; Auma, Mercy; Fellah, Z. E. A.; Mageto, Maxwell; Ben Mansour, Mohamed; Oduor, Andrew
    This study assessed the potential use of a mixture of lime and water hyacinth ash (WHA) as binders in fabrication of cylindrical compressed earth blocks (CEBs) with good acoustic absorption properties for building and construction. Different concentrations of the binders and compaction pressures were employed so as to vary the acoustical properties of the fabricated blocks. The geometric and transport parameters of their porous microstructure were recovered through probing using acoustic waves. A low-frequency acoustic wave guide was built for this purpose. It was found out that the transmission coefficient decreased with the compaction pressure, and with addition of lime, while WHA increased the transmission coefficient. The non-acoustical parameters recovered using the equivalent fluid model (JCAL) showed that the variation of the geometry of the microstructure of the blocks is what influences the acoustic transmission coefficient. Thus, the properties of the CEBs can be steered using binder concentration and compaction pressure in a controlled manner.
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    Publication
    Electrical and Structural Properties of Aluminium Doped tin Oxide Codoped with Sulphur for Solar Energy
    (Elsevier, 2016-08) Muramba, Valentine Wabwire; Mageto, Maxwell
    Thin films of Tin Oxide co-doped with 28 atomic percentages of Aluminium (i.e. 28 at% Al) and varied concentration of Sulphur were prepared on 1mm thick, 1cm by 1cm glass substrates at 470 0C by Spray Pyrolysis technique. Films were produced from 2.0M solution of hydrous Tin Chloride dissolved in Ethanol with 38% Hydrochloric acid concentration, 1.5M aqueous Aluminium chloride and 2.0M aqueous solution of Ammonium Sulphide. The effects of Sulphur concentration on structural and electrical properties of transparent Tin Oxide thin films were investigated in the atomic percentage of Sulphur content ranging from zero to fifty (i.e. 0at%S -50at%S) with a fixed 28at%Al content. Polycrystalline structures without any second phases were observed with preferential orientations along the (110), (101), (200) and (211) planes. The average grain size as determined from the (110) peaks lay in the range 19.2 nm-47.7nm. The minimum resistivity was found to be 1.15x10-3Ωcm for the Tin Oxide films doped with 32 at% Al content and 9.59x10-3Ωcm for Tin Oxide films co-doped with 28 at% Al and 20 at% S content. It was observed that Aluminium doping lowered the grain size significantly but doping to optimum level of 32 at% Al content increases electrical conductivity of tin oxide. When Sulphur was intentionally introduced in the crystal structure of 28 at% Al doped Tin Oxide, the electrical conductivity decreased appreciably and the grain size increased.
  • Publication
    Publication
    Electrical and Structural Properties of Aluminium Doped tin Oxide Codoped with Sulphur for Solar Energy
    (Elsevier, 2016-08) Muramba, Valentine Wabwire; Mageto, Maxwell
    Thin films of Tin Oxide co-doped with 28 atomic percentages of Aluminium (i.e. 28 at% Al) and varied concentration of Sulphur were prepared on 1mm thick, 1cm by 1cm glass substrates at 470 0C by Spray Pyrolysis technique. Films were produced from 2.0M solution of hydrous Tin Chloride dissolved in Ethanol with 38% Hydrochloric acid concentration, 1.5M aqueous Aluminium chloride and 2.0M aqueous solution of Ammonium Sulphide. The effects of Sulphur concentration on structural and electrical properties of transparent Tin Oxide thin films were investigated in the atomic percentage of Sulphur content ranging from zero to fifty (i.e. 0at%S -50at%S) with a fixed 28at%Al content. Polycrystalline structures without any second phases were observed with preferential orientations along the (110), (101), (200) and (211) planes. The average grain size as determined from the (110) peaks lay in the range 19.2 nm-47.7nm. The minimum resistivity was found to be 1.15x10-3Ωcm for the Tin Oxide films doped with 32 at% Al content and 9.59x10-3Ωcm for Tin Oxide films co-doped with 28 at% Al and 20 at% S content. It was observed that Aluminium doping lowered the grain size significantly but doping to optimum level of 32 at% Al content increases electrical conductivity of tin oxide. When Sulphur was intentionally introduced in the crystal structure of 28 at% Al doped Tin Oxide, the electrical conductivity decreased appreciably and the grain size increased.
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    Publication
    Numerical Study of Copper Antimony Sulphide (CuSbS2) Solar Cell by SCAPS-1D
    (Heliyon, 2023-07-27) Obare, Nancy; Isoe, Wycliffe; Nalianya, Amos; Mageto, Maxwell; Odari, Victor
    Copper antimony sulphide has ability in applications on photovoltaics since it is a promising, less toxic, earth abundant absorber material. In this study, the photovoltaic characteristics of copper antimony sulphide (CuSbS2) photovoltaic cell were simulated and studied by one dimensional solar cell capacitance simulator (SCAPS-1D) to improve their operations. This study investigated the impact of modifying the thicknesses of fluorine-doped tin oxide (FTO), cadmium sulphide (CdS), carbon(C), and CuSbS2 absorber layer, Also the amount of doping and the number of defects on CuSbS2 photoactive layer, the structure of the solar cell is made up of glass, FTO, n-CdS, p-CuSbS2, C, and Au. The optimum parameters of the designed photovoltaic cell yielded 0.9388 V of open-circuit voltage (Voc), the short-circuit current density (Jsc) was 28.31 mA/cm2, the fill factor (FF) of 60.8%, and the solar cell efficiency of 16.17%. The ideal thickness was discovered to be 300 nm for the CuSbS2 solar cell. The defect density increment led to a decrease in carrier lifetime resulting also to decrease in diffusion length and the optimum absorber layer doping concentration was found to be 1018 cm-3
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    Publication
    Numerical study of lead free CsSn0.5Ge0.5I3 perovskite solar cell by SCAPS-1D
    (Elsevier, 2021-12) Nalianya, Milimo Amos; Awino, Celline; Barasa, Henry; Odari, Victor; Gaitho, Francis; Omogo, Benard; Mageto, Maxwell
    Lead free perovskite solar cells (PCS) are becoming a distinctly predominant area of study due to the toxicity and stability hurdles of the lead halide perovskite. Current lead-free perovskites are also plagued with low efficiency. This work is concerned with the design and analysis of CsSnGeI3 that is a viable competitor to lead based perovskites by SCAPS-1D simulator (ver.3.3.08). The primary solar cell’s structure is FTO/PCBM/ CsSn0.5Ge0.5I3 / spiro-OMeTAD/Au which achieved a power conversion efficiency (PCE) of 7.11% [1]. To enhance device performance, the effect of optimizing absorber layer defect density (1 × 1015 cm−3) and thickness (700–800 nm), doping concentration of absorber layer (1 × 1015 cm−3), variation of Electron Transport Material (ETL) and Hole Transport Material (HTL) parameters (effect of CBO and VBO and doping concentration) and potential material options for ETL and HTL are studied. The results of the simulation are as follows; maximum power conversion efficiency (PCE) 18.79%, short circuit current density (Jsc) 27.05 mA/cm2, open circuit voltage (Voc) 0.87 V and fill factor (FF) 79.25%. By choosing appropriate material parameters, improving fabrication and encapsulation processes, CsSn0.5Ge0.5I3 proves to be an environmentally friendly solar cell with high efficiency.
  • Publication
    Publication
    Thickness Dependence of Window Layer on CH3NH3PbI3-XClX Perovskite Solar Cell
    (International Journal of Photoenergy, 2020-07-28) Isoe, Wycliffe; Mageto, Maxwell; Maghanga, Christopher; Mwamburi, Maurice; Odari, Victor; Awino, Celline
    CH3NH3PbI3-xClx has been studied experimentally and has shown promising results for photovoltaic application. To enhance its performance, this study investigated the effect of varying thickness of FTO, TiO2, and CH3NH3PbI3-xClx for a perovskite solar cell with the structure glass/FTO/TiO2/CH3NH3PbI3-xClx/Spiro-OMeTAD/Ag studied using SCAPS-1D simulator software. The output parameters obtained from the literature for the device were 26.11 mA/cm2, 1.25 V, 69.89%, and 22.72% for Jsc, Voc, FF, and , respectively. The optimized solar cell had a thickness of 100 nm, 50 nm, and 300 nm for FTO, TiO2, and CH3NH3PbI3-xClx layers, respectively, and the device output were 25.79 mA/cm2, 1.45 V, 78.87%, and 29.56% for Jsc, Voc, FF, and , respectively, showing a remarkable increase in FF by 8.98% and 6.84% for solar cell efficiency. These results show the potential of fabricating an improved CH3NH3PbI3-xClx perovskite solar cell.