25%, approaching that of established single crystal silicon cells. [5] The stability of PSCs has also been greatly improved and basically reach the required standard for industrial application. [6,7] Recently, the PCE of large-area perovskite modules has also been improved high enough to be comparable to that of the prevailing polycrystalline silicon solar cells for large-scale applications. [8] All these developments have demonstrated the great promise of PSCs as cost-effective next-generation photovoltaic technology. Nevertheless, an unavoidable barrier remains blocking their way toward practical application is the environmental contamination with water-dissolved lead ions from the lead halide perovskites. [9][10][11][12] Therefore, in the process of promoting the real application of PSCs, the elimination of lead leakage should be strengthened while pursuing high efficiency and high stability.Although the efficiency is already quite high, there is still room for improvement in the performance of PSCs. As the most crucial functional layer in PSCs, the perovskite films prepared by solution method usually have various defects at the surface and grain boundaries. [13][14][15] These defects not only easily become the corrosion sites of water and oxygen in the surrounding environment, causing the degradation of perovskite film, but also closely related to the nonradiative charge recombination in the device, resulting in the significant reduction of With the continuous improvement of performance of lead-based perovskite solar cells (PSCs), the potential harm of water-soluble lead ion (Pb 2+ ) to environment and public health is emerging as a major obstacle to their commercialization. Herein, an amphoteric phenylbenzimidazole sulfonic acid (PBSA) that is almost insoluble in water is added to the perovskite precursor to simultaneously regulate crystallization growth, passivate defects, and mitigate lead leakage of high-performance PSCs. Through systematic research, it is found that PBSA can not only regulate the crystallization of perovskite grains to form the film, but also passivate the defects of annealed films mainly due to the strong interaction between the functional groups in PBSA and Pb 2+ , which greatly improves the crystallinity and stability of perovskite films. Consequently, the highest power conversion efficiency of 23.27% is achieved in 0.09 cm 2 devices and 15.31% is obtained for large-area modules with an aperture area of 19.32 cm 2 , along with negligible hysteresis and improved stability. Moreover, the leakage of lead ions from unpackaged devices is effectively prevented owing to the strong coupling between PBSA molecules and water-soluble Pb 2+ to form insoluble complexes in water, which is of great significance to promote the application of optoelectronic devices based on lead-based perovskite materials.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smtd.202101257.

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Expeditious charge transfer at the interfaces between photoactive and charge transport layers is critical in perovskite solar cells (PSCs). Defects on the surface of charge transport layers usually lead to the degradation of carrier mobility, resulting in low power conversion efficiency (PCE) and serious hysteresis. Herein, phosphorus‐containing Lewis acids are applied to modify the SnO2/perovskite interface and neutralize redundant OH− on the SnO2 surface. The interaction between the Lewis acids and SnO2 significantly accelerate the electron transfer and greatly reduce the energy barrier at the SnO2/perovskite interface, boosting the PCE of the PSCs. By modifying the SnO2/pervoskite interface with diphenylphosphine oxide, the PCE of a small area device was increased from 18.94% to 22.14%, along with negligible hysteresis and improved stability. Moreover, the 5 × 5 cm2 solar modules with an aperture area of 22.56 cm2 achieved a best efficiency of 15.69%.

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