Surface- or bulk-passivation using organic additives plays a critical role in improving the performance and stability of hybrid perovskite solar cells (HPSCs). Here, we report 2-hydroxyethyl acrylate (HEA) as an additive to reduce crystallization and passivate defects. Because of the dual functionality of the HEA additive, the optimized HPSCs yield 22.05% and 21.46% power conversion efficiency (PCE), respectively, for mesostructured negative-intrinsic-positive (n-i-p)- and planar positive-intrinsic-negative (p-i-n)-type device configurations, which is much higher than control devices. Large devices with 1 cm2 active area also produce a promising 20.03% PCE, which is comparable to the current efficiency. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) measurement analysis indicates the HEA settles not only in grain boundaries but also within the perovskite grain, which facilitates passivation and suppresses halogen-ion migration. Importantly, photostability analysis reveals negligible efficiency loss over 1,000 h under continuous 1 sun illumination under different environmental conditions
