Multi‐Dimensional Stress Release by Interfacial Embedding of Nanolubricants for Mechanically Stable Perovskite Solar Cells

Abstract Managing residual stress in hybrid perovskites is crucial for achieving mechanically stable perovskite solar cells (PSCs) with high power conversion efficiency (PCE), while challenges remain for synchronous stress regulation in multiple dimensions during solution‐processing. Herein, a grain‐boundary‐lubricating strategy is demonstrated to relieve stress within perovskite films—both in‐plane and out‐of‐plane—for enhancing the mechanical integrity of PSCs. As a proof of concept, laser‐manufactured multilayer nanolubricants of WSe 2 are embedded at grain boundaries (GBs) of perovskite films, linking adjacent grains through interactions between uncoordinated Pb and active Se atoms. This multi‐dimensional stress release significantly reduces stress concentration at GBs, shifting the fracture mode of perovskite films from intergranular to transgranular, thereby improving the mechanical reliability of PSCs under external stress. Such linking also facilitates charge transport while the rationally selected nanolubricant can passivate interfacial defects. The resultant PSCs deliver PCEs of over 25% with pronounced environmental stability, and demonstrate exceptional mechanical durability, retaining 88.3% of their initial PCE even after 10 000 bending cycles at a bending radius of 3 mm. This work opens a new avenue for stress management in PSCs via the interfacial embedding of nanolubricants.