Highly Efficient And Stable Two-Dimensional Perovskite Solar Cells Via Engineering Crystallization And Orientation

Abstract

2D perovskites offer greater stability but lag in PCE due to the poor conductivity of bulky organic spacers that hinder carrier transport. This thesis aims to narrow the PCE gap between 2D and 3D PSCs by refining crystallization processes, optimizing crystal orientation, and improving film quality, thereby advancing the practical application of 2D PSCs in renewable energy. In Chapters 1-2, we introduce the origins of solar cells, tracing developments from the initial discoveries of the photovoltaic and photoelectric effects to the evolution of crystalline silicon and thinfilm solar cells. In Chapter 3, we introduced some fabrication methods used for each layer of perovskite solar cells. Next, we introduce the principles and detailed methods of the characterization techniques. In Chapter 4, We aim to address the inherent stability in FA-based 2D perovskites, especially lattice strain and poor carrier transport. Through spacer cation engineering, we achieved a stable perovskite lattice structure with relaxed microstrain and reduced carrier-lattice interactions. In Chapter 5, we aim to address the issues related to low crystallinity and disordered orientation in low-n 2D perovskite solar cell, which restrict carrier transport and efficiency. We found that effectively NH4+SCN additives retarded non-uniform crystallization, promoting vertical quantum well growth. In Chapter 6, we introduce a novel de-templated crystallization strategy designed to control the crystallization kinetics of 2D perovskite film. We successfully eliminate the templated in-plane growth near the liquid-air interface and promote the formation of highly out-of-plane orientated crystals. In Chapter 7, we summarized the development and advantages of PSCs and provided the perspective research directions in 2D halide perovskites for further optoelectronic applications.