Stability of perovskite solar cell

Abstract

Solar cells, which can convert sunlight into electric energy, have attracted much attention with the increasing demand for renewable energy. Perovskite solar cells (PSCs) have attracted attention with high PCE (~26.7%) and low processing temperature. However, the commercialization of PSCs has been hindered by poor stability due to the sensitivity of perovskite to environmental factors. The objective of this thesis is to investigate the mechanisms behind the degradation of perovskite solar cells (PSCs) and to identify effective methods to enhance their stability. Chapter 1 provides an overview of PSCs, discussing the inherent properties of perovskite materials, the architecture of PSCs, and the challenges related to their stability, along with existing strategies to mitigate these issues. Chapter 2 describes the methodologies applied in this research, including PSCs fabrication, characterization techniques, and morphological investigations. Chapter 3 investigated the effect of Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) 2D perovskite on the stability of 2D/3D perovskite against the photo-oxidation. The PSCs modified with DJ perovskite exhibit significant reduction in ion migration and longer lifetime compared to those modified with RP perovskite. In Chapter 4, a comparative study of the stability of various perovskite compositions under different experimental conditions was conducted. Among 3 types of perovskites investigated, the Cs0.1FA0.9PbI2.9Br0.1 (MA-free) perovskite exhibits the highest resistance to thermal stress, illumination, oxygen, while it is still sensitive to the presence of moisture. To enhance the stability against 6 moisture, three types of additives to MA-free perovskite were studied, with the cross-linkable additive showing the most considerable improvement in moisture resistance Finally, Chapter 5 focuses on the optimization of PSCs through the application of self-assembled monolayers (SAMs). The study explored the dual modification with small phosphonic acid molecules and carbazole-based SAMs, which alleviate the photo-induced segregation of perovskite on top. Additionally, the role of SAMs in adjusting energy levels was examined to reduce the adverse effects of thick 2D perovskite layers on electron collection.