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Bello, Oluwaseyi Oluwatimileyin and Covenant University, Theses (2021) SYNTHESIS, CHARACTERIZATION, AND ANALYSIS OF LEAD-FREE INORGANIC PEROVSKITE FOR SOLAR CELL APPLICATION. Masters thesis, Covenant University Ota..

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Perovskites are at the forefront of research into possible replacements for cumbersome and expensive silicon based solar cells. Lead based inorganic and organic-inorganic hybrid perovskite solar cells have been breaking records for efficiency, approaching 25% in recent years. However, these suffer from instability problems along with the possible health hazards in the long term. Hence, there has been a parallel search for lead-free, and preferably inorganic, perovskite solar cells in the hope of matching and ultimately exceeding the achievements of lead perovskite analogues. Based on in-depth literature review, this research proposed that structural modifications of perovskite using stoichiometry, dopants, and additives be used as a unique technique for enhancing the efficiency of lead-free inorganic perovskites. Four inorganic perovskites were synthesized via solution and solid-state reaction methods with several additives (such as plant extracts and Isopropanol) and dopants (such as copper and silver). The plants extracts were obtained from Buxus sempervirens, Cercis Occidentalis, Plecranthus scutellariodes, Kola Nitida, Carica Papaya, Ficus Exasperata, and Musa Paradisiaca. The optical characterization was carried out using X-ray Fluorescence spectroscopy (XRF), and Ultraviolet-Visible (UV-VIS) spectroscopy. The electronic characterization was performed using SCAPS-1D to obtain Power Conversion Efficiency (PCE), current density, voltage, doping density, flat band potential, and external quantum efficiency (QE). CaZnBr3 had an efficiency of 7.52% at 100 μm, with a band gap of 3.658 eV. As a pure lead-free inorganic perovskite, it is already higher than existing lead-free inorganic perovskites. When Buxus Sempervirens extract was added, the efficiency improves to 9.71% at 0.2 g and 9.74% at 0.5 g. NaCaZn2Br6 had low efficiency because of its low short circuit current density (Jsc), steep Mott Schottky curve, and low QE. Na2Zn2Br6 performs better as a double perovskite, with higher efficiency of 8.31% in its pure form than CaZnBr3, with an optimized efficiency of 9.78% when doped with 0.2 g of Musa paradisiaca extract. In conclusion, the use of stoichiometry, dopants, and additives for structural modifications of inorganic perovskites has been proposed for obtaining new perovskite candidates and PCE optimization. It is recommended that the novel double perovskite Na2Zn2Br6 be researched further using different synthetic routes.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Perovskite, Dopants, Characterization, Synthesis, Additives, SCAPS-1D.
Subjects: Q Science > QC Physics
Divisions: Faculty of Engineering, Science and Mathematics > School of Physics
Depositing User: Mrs Patricia Nwokealisi
Date Deposited: 31 Jan 2022 16:33
Last Modified: 31 Jan 2022 16:33

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