Additive‐Mediated (111)‐Facet‐Oriented Perovskite Films via Two‐Step Blade‐Coating for Efficient and Stable Inverted Solar Cells

Efficiency and stability have long been bottlenecks hindering the rapid development of perovskite solar cells (PSCs). To address the stability issues of inverted perovskite cells, this work introduced propylammonium iodide (PAI) as an additive into the lead iodide precursor, achieving growth with preferential crystal orientation. The device set a new stability record, maintaining 95% of its initial efficiency after 1680 h of continuous operation in maximum power point tracking, and achieved a photoconversion efficiency of 20.05%. Density functional theory calculations revealed that the binding energy of the PA + cation on the perovskite (111) crystal plane (−0.83 eV) is significantly higher than that on the (100) crystal plane (−0.43 eV), which gives the (111) crystal plane a more pronounced competitive growth advantage over the (100) crystal plane, thus enabling the preparation of perovskite films dominated by the (111) orientation. Further studies indicate that the (111) crystal plane is perpendicular to the normal direction of the film surface, and it is precisely this structure that achieves high stability. Based on the study of introducing PAI additives in the two‐step blade‐coating of inverted perovskites, this work successfully controlled the growth mechanisms of the (111) and (100) crystal orientations, providing an approach for achieving high stability in PSCs.