Passivation strategies for the optimization of perovskite solar cells

This thesis focuses on developing environmentally sustainable strategies to enhance the performance, stability, and scalability of PSCs, among the most promising PV technologies of the current scenario. The experimental results are organized in three sections, chapters 3 to 5, the first one employing bio-derived materials as components of the PSC device foreseeing the amelioration of the photoactive film characteristics combined with the engineering of device interfaces. In details, chapter 3 reports on the use of β-carotene and PHB, to improve the environmental stability and optoelectronic properties of perovskite films. β-carotene, which scavenges oxidizing species, mitigates perovskite degradation, leading to increased material stability and prolonged charge carrier lifetimes. Devices incorporating β-carotene achieve a PCE of 20%, highlighting its potential to improve the lifespan and sustainability of solar cells. Similarly, PHB, a biodegradable polymer, enhances the mechanical flexibility and crystalline quality of perovskite films, and surpasses the reference efficiency, achieving a PCE of 9.3%. This suggests the potential of PHB to contribute to the development of more sustainable, flexible, and eco-friendly perovskite-based devices. The second section is focused on the key role of device interfaces for fully inorganic CsPbI₃-based solar cells. The incorporation of PCBM as an interlayer between C₆₀ and CsPbI₃ enhances energy level alignment and reduces defects, contributing to more efficient charge transfer. Successively, the introduction of TTH as a novel interlayer further improves device performance, with a PCE of 8.12% surpassing the reference efficiency of 6%, by reducing interfacial recombination and facilitating efficient charge separation. These innovations demonstrate the potential to optimize perovskite-based devices for more sustainable energy solutions. Finally, in chapter 5 plasma-based treatments are explored as environmentally friendly surface modification methods for MAPbI3 perovskite films. Plasma treatments with gases like Ar and H₂ enhance device performance by selectively removing organic components and introducing chemical functionalities that improve the stability and efficiency of the interfaces. Unlike traditional chemical treatments, plasma-based methods offer a less invasive and potentially more eco-friendly approach to surface engineering. In conclusion, this thesis demonstrates the potential of combining bio-inspired additives, interlayer engineering, and plasma treatments to address key challenges in perovskite solar cell technology. These advancements not only improve the efficiency and stability of the devices but also pave the way for the development of more environmentally sustainable and scalable photovoltaic solutions, contributing to the global transition towards clean and renewable energy sources.