Physics

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Physics

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Author: search.filters.author.YUSUF Abubakar Sadiq

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    Effect of Natural Dye Co-Sensitization on the Performance of Dye-Sensitized Solar Cells (DSSCS) Based on Anthocyanin and Betalain Pigments Sensitisation
    (European Journal of Applied Sciences 9 (3): 140-146, 2017 ISSN 2079-2077, 2017-01-01) YUSUF Abubakar Sadiq; K.U. Isah; B.J. Jolayemi
    Dye-sensitized solar cells (DSSCs) were prepared using natural pigments containing anthocyanin and betalain extracted from Flame tree and Bougainvillea glabra flowers respectively as sensitizers. The dyes were used as lone sensitizers exploring anthocyanin and betalain separately and as co-sensitizers exploring the combined anthocyanin and betalain (water extract) and combined anthocyanin and betalain (ethanol extract) separately. The effects of the sensitizers on the performance of the DSSCs were investigated, the study reveals that all the cells possess comparable values of V of about 0.55 0.1 V. However, of the two lone sensitisers,oc betalain based device gave a better efficiency of 0.21% while anthocynin based device achieved 0.17 %, this is attributed to their different anchoring functional groups. The, combined anthocyanin and betalain dyes (water extract) had the highest conversion efficiency of 0.26 % suggesting dye synergic absorption effect as a result of co-sensitisation, the lower efficiency of 0.24 %) achieved by combined anthocyanin and betalain (ethanol extract) is attributed to the contributory effect of the extraction solvents
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    Optimizing the resistivity of colloidal SnO2 thin films by ion implantation and annealing
    (Surfaces and Interfaces Volume 55, December 2024, 105325, 2024-11-01) YUSUF Abubakar Sadiq; Martin Markwitz; Zhan Chen; Maziar Ramezani; John V. Kennedy; Holger Fiedler
    Tin oxide (SnO2) is a critical material for a wide range of applications, such as in perovskite solar cells, gas sensors, as well as for photocatalysis. For these applications the transparency to visible light, high availability, cheap fabrication process and high conductivity of SnO2 benefits its commercial deployment. In this paper, we demonstrate that the resistivity of widely colloidal SnO2 can be reduced by noble gas ion beam modification. After low energy argon implantation with a fluence of 4×1015 at.cm−2 at 25keV and annealing at 200°C in air, the resistivity of as-deposited film was reduced from (178±6)μΩcm to (133±5)μΩcm, a reduction of 25%. Hall effect measurements showed that the primary cause of this is the increase in carrier concentration from (8.1±0.3)×1020 cm−3 to (9.9±0.3)×1020 cm−3. Annealing at 200°C resulted in the removal of defect clusters introduced by implantation, while annealing at 300°C resulted in the oxidation of the films, increasing their resistivity. The concentration of oxygen vacancy defects can be controlled by a combination of low energy noble gas ion implantation and annealing, providing promising performance increases for potential applications of SnO2 where a low resistivity is crucial. Graphical abstract