Advanced spectroscopic techniques for characterizing defects in perovskite solar cells

Abstract There is currently substantial interest in commercializing perovskite solar cells as they offer superior properties over silicon-based solar cells, such as ability for bandgap tuning, higher absorption coefficients, and potentially lower manufacturing costs. However, trap states originating from ionic vacancies, imperfect interfaces, and grain boundaries have hampered their performance and long-term stability during operation. Identifying and quantifying defects in perovskite solar cells becomes inevitable to address these challenges and mitigate the deteriorating effects of these defects. This Review focuses on recent developments in optical and electrical characterization techniques employed for the investigation of defects in halide perovskites and the techniques to understand ion migration in devices. We focus on sample preparation, advantages, limitations, and the nature of information obtained from each of the spectroscopic techniques. This Review will enable the researchers to understand and identify suitable characterization techniques for characterizing defect concentrations and their energetic and spatial distribution in perovskite solar cells.