Dimensionality and Composition Modifications for Highly Efficient and Durable Perovskite Solar Cells

This thesis presents a comprehensive study aimed at enhancing the performance and stability of perovskite photovoltaic cells. Perovskite solar cells represent a promising area in solar technology, but they face challenges including repeatability of the fabrication process and cell degradation over time. In addressing these challenges, the research focused on modifications of both perovskite chemical composition and perovskite solar cell structure. It was shown that the addition of camphorsulfonic acid (CSA) in the active layer of solar cells is an effective method for enhancing performance. This strategy resulted in significant improvements in material quality and grain sizes, boosting the efficiency by 20% compared to CSA-free reference. The research also delves into the development of a unique hole transport layer (HTL) using chemically synthesized polyaniline protonated with CSA. While this approach led to slightly lower efficiency compared to conventional methods, it demonstrated potential for boosting the long-term stability of the cells. A significant portion of this work investigates the degradation mechanisms in perovskites, with a particular focus on the influence of oxygen and water diffusion. The study presents insightful findings on the impact of environmental factors on perovskite stability and proposes potential mitigation strategies, including the fabrication of quasi-3D perovskites or a partial substitution of iodine with bromine. In addition to perovskite chemistry modifications, an Al2O3 protective layer was applied onto the perovskites using Atomic Layer Deposition (ALD), which effectively limited both oxygen and water diffusion, thereby enhancing the stability of the perovskite layers and solar cells. A non-standard in-situ technique of solidification processes and hydration of perovskite materials was utilized, proved to be highly fruitful in understanding the impact of precursor composition on the rate of crystallization processes and the resulting material structure. Furthermore, this technique enabled the tracing hydration processes and the determination of conditions for reversible hydration of perovskites. Systematic studies of the degradation of modified perovskites (quasi-3D), iodide, and those mixed with bromine were conducted over 120 days. While classic 3D perovskites completely degraded within this timeframe, the newly developed perovskite formulations (quasi-3D) retained a significant portion of their original structure, demonstrating the effectiveness of the applied approach. The work conducted provides novel insight into understanding degradation processes, as along with new strategies to enhance repeatability, efficiency, and durability of perovskite-based solar cells. The author hopes that these findings will serve as a foundation for future research in this exciting field.