BOOSTING STABILITY AND EFFICIENCY IN PEROVSKITE SOLAR CELLS BY UTILIZATION OF PASSIVATORS AND ORGANIC CHARGE CARRIERS

Date

2024-11-21

Author

Gözükara Karabağ, Zeynep

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Lead-based perovskite materials are promising in photovoltaics due to exceptional properties such as high absorption coefficients, carrier mobility, and tunable bandgap. However, enhancing the stability of perovskite solar cells (PSCs) is a critical challenge. One effective strategy is surface passivation, mainly using 2D perovskites based on phenylethylammonium (PEA+) salts. Systematic studies conducted in this thesis revealed that halogenated PEA+ salts, like meta-bromo phenylethylammonium iodide (m-BrPEAI), yield high efficiencies (23.42%). In contrast, meta-chloro phenylethylammonium iodide (m-ClPEAI)-treated cells provide superior stability and reproducibility. Methoxylated PEA+ salts, particularly ortho-methoxy phenylethylammonium iodide (o-OMe-PEAI), reduce defect densities and nonradiative recombination rates, leading to power conversion efficiencies (PCEs) over 23%. Density functional theory (DFT) suggests these improvements result from favorable formation energies and optimal molecular orientations. Furthermore, the design and synthesis of thermally evaporable DFH (N2,N2,N7,N7- tetra-ptolylspiro[fluorene-9,2′-[1,3]dioxolane]-2,7-diamine)-based NiOx passivation molecules and naphthalene diimide (NDI) derivatives as fullerene alternatives were realized. Their preliminary performance was demonstrated in inverted PSCs. Polymeric passivation layers have great potential to enhance the performance of PSCs. Diketopyrrolopyrrole (DPP)-based polymers integrated into cesium formamidinium methylammonium (CsFAMA)-based perovskites improve crystallization, defect management, ambient and thermal stability. In this work, PSCs utilizing novel polymeric additive 1 (poly-ADD1) achieve efficiencies of nearly 21%, significantly surpassing those of unmodified cells. It retains 67% of its efficiency after 1600 hours of storage at 85 °C in an ambient environment compared to reference devices, retaining 29% of its initial PCE. This research provides critical insights into the development of innovative passivation techniques. It offers solutions to the stability challenges of PSCs and extends their longevity within the industry.

Subject Keywords

Perovskite Solar Cells, 2D Perovskite Passivation, Stability, DPP-Based Polymeric Passivation, Organic Charge Transport Materials

URI

https://hdl.handle.net/11511/112963

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Graduate School of Natural and Applied Sciences, Thesis