Browsing by Author "Mdluli, Siyabonga Beizel"

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    Novel heterojunction superstrate Cu2ZnInS4−x (CZIS) thin film kesterite solar cell with vertical arrays of hexagonal ZnO nanorods window layer
    (Elsevier, 2022-11-24) Yussuf, Sodiq Tolulope; Ramoroka, Morongwa Emmanuel; Mdluli, Siyabonga Beizel; Nwambaekwe, Kelechi Chiemezie; Ekwere, Precious Idinma; Uhuo, Onyinyechi Vivian; Ikpo, Chinwe Oluchi; Iwuoha, Emmanuel Iheanyichukwu
    Quaternary Cu2ZnInS4−x (CZIS) thin films have been prepared by a facile and cheap sol-gel spin coating technique. Low-temperature solution-based methods were used to fabricate a heterojunction solar cell in the superstrate architecture with CZIS thin film as the absorber, vertically aligned ZnO nanorod arrays, and CdS as the window and buffer layers respectively. ZnO nanorod arrays were prepared by hydrothermal technique and nanocrystal layer deposition technique were employed for the deposition of CdS-coated ZnO nanorod arrays. CZIS absorber layer was spin coated on the CdS-coated ZnO nanorod arrays and annealed at different temperatures. The vertically aligned ZnO nanorod arrays, and uniformly distributed CdS shell layer were confirmed from morphological studies. The device had a final configuration of Glass/ITO/ZnO NRs/CdS/ CZIS/Ag. HRSEM revealed a nanoflake-like morphology and a band gap between 1.5 and 1.77 eV for the CZIS thin films. CZIS superstrate solar cell had a power conversion efficiency of ∼ 0.61%, an open circuit voltage of ∼ 0.8 V, a short circuit current of ∼ 0.95 mA cm−2 and a fill factor of ∼ 61.35%. This method demonstrates a novel, facile and eco-friendly technique for synthesizing nanocrystalline CZIS thin films with promising photo response from the fabricated device indicating a proof of principle that this material can find application in solar cells.
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    Photoluminescent Responses of Polypropylenethiophenoimine-Co-Pedot/ Polystyrenesulfonic Acid and Zinc Selenide Quantum Dot Composite Materials
    (University of the Western Cape, 2018) Mdluli, Siyabonga Beizel; Iwuoha, Emmanuel I.; Modibane, Kwena D.
    Research in renewable energy has gained momentum and become a centre of attention as a possible alternative solution to the energy catastrophe. This is attained by the use of solar energy as an alternative clean energy source. The creation of solar energy arises as a consequence of direct conversion of light photons from the sun into electrical energy by the use of solar cells made up of semiconducting materials incorporated into the system. In the context of solar energy, hybrid photovoltaics comprising of organic molecules and nanomaterials have emerged to be one of the most promising candidates to lower the cost of construction of solar cells as well as improving the power conversion efficiency (PCE). This is mainly due to the ease of processability of the active layer and the unique properties brought by the use of nanomaterials. In the exponential increasing wide field of nanotechnology, focus has shifted to novel hybrid dendritic star copolymers as the organic donor materials and quantum dots as the inorganic acceptor materials.
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    Synthesis and photovoltaics of novel 2,3,4,5-tetrathienylthiophene-co-poly(3-hexylthiophene-2,5-diyl) donor polymer for organic solar cell
    (MPDI, 2021) Ramoroka, Morongwa E.; Mdluli, Siyabonga Beizel; John-Denk, Vivian S.
    This report focuses on the synthesis of novel 2,3,4,5-tetrathienylthiophene-co-poly(3-hexylthiophene-2,5-diyl) (TTT-co-P3HT) as a donor material for organic solar cells (OSCs). The properties of the synthesized TTT-co-P3HT were compared with those of poly(3-hexylthiophene-2,5-diyl (P3HT). The structure of TTT-co-P3HT was studied using nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FTIR). It was seen that TTT-co-P3HT possessed a broader electrochemical and optical band-gap as compared to P3HT. Cyclic voltammetry (CV) was used to determine lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy gaps of TTT-co-P3HT and P3HT were found to be 2.19 and 1.97 eV, respectively. Photoluminescence revealed that TTT-co-P3HT:PC71 BM have insuffi-cient electron/hole separation and charge transfer when compared to P3HT:PC71 BM. All devices were fabricated outside a glovebox. Power conversion efficiency (PCE) of 1.15% was obtained for P3HT:PC71 BM device and 0.14% was obtained for TTT-co-P3HT:PC71 BM device. Further studies were done on fabricated OSCs during this work using electrochemical methods.