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Perovskite solar cells have made significant strides in recent years. However, there are still challenges in terms of photoelectric conversion efficiency and long-term stability associated with perovskite solar cells. The presence of defects in perovskite materials is one of the important influencing factors leading to subpar film quality. Adopting additives to passivate defects within perovskite materials is an effective approach. Therefore, we first discuss the types of defects that occur in perovskite materials and the mechanisms of their effect on performance. Then, several types of additives used in perovskite solar cells are discussed, including ionic compounds, organic molecules, polymers, etc. This review provides guidance for the future development of more sustainable and effective additives to improve the performance of solar cells.

Multifunctional buried interface modification is key to boost the performance of perovskite solar cells (PSCs). Herein, a multifunctional passivator, N-(2-hydroxyethyl) ethylene diamine triacetic acid trisodium salt (HEDTA-3Na), is employed to modify an SnO2 electron transport layer (ETL) for fabricating efficient and stable PSCs. It is found that the addition of HEDTA-3Na not only reduces defect state density by passivating uncoordinated Sn4+ and Pb2+ defects in an ETL/perovskite interface, but also forms appropriate energy band alignment, facilitating electron extraction, and improves the quality of the perovskite film with enlarged grain sizes. In addition, the Na+ ions can diffuse into the perovskite layer to passivate iodine vacancy defects and inhibit ion migration. As a result, the PSC with HEDTA-3Na modification achieves a champion PCE of 23.11% with enhanced VOC and FF compared to the control device (20.82%). Moreover, the unencapsulated HEDTA-3Na-modified PSC retains 90% of its initial efficiency after 1600 hours at 25 °C and 20–25% relative humidity under ambient conditions. This work offers a simple and effective approach to synergistically improve the performance of PSCs with a single multifunctional molecule. [ABSTRACT FROM AUTHOR]