Abstract:The buried interface defects of inverted perovskite solar cells are a significant factor that can suppress the performance and lifetime of these solar cell devices.These defects can constrain the efficiency and stability, making it cru• cial to solve them for improved solar cell performance.Using organic small molecules as passivation materials has been shown to be an effective strategy to mitigate these interface defects, thereby reducing the non-radiative recombination of charge carriers.In this study, we have successfully integrated a kind of passivation material with a self-assembled hole transporting layer, enabling a one-step passivation of the buried interface with a two-dimensional perovskite material.Af• ter the deposition of the perovskite film, the number of excess lead iodide particles at the buried bottom interface was sig• nificantly reduced, and the presence of two-dimensional perovskite was detected, from which it can be hypothesized that the passivation material at the bottom reacted with the lead iodide to synthesize it.This innovative approach significantly improves the efficiency of solar cells, especially the V oc and device reproducibility due to the reduction of buried interface defects.Our results demonstrate that through the passivation of the buried interface, we were able to achieve an impres• sive efficiency of 21. 42% by using blade coating.Furthermore, to validate the scalability and practicality of our method, we fabricated perovskite solar modules with an aperture area of 21. 5 cm 2 .These modules achieved an efficiency of 21. 02% and remained stable for almost 1 000 h at 85 ℃ and 85% humidity after proper encapsulation.The simplicity and efficiency of this process confirm the potential for large-scale applications in perovskite solar cell technology. Key words: perovskite solar cell; buried interface; passivation; self-assembled monolayer; high efficiency