Universal Ion Migration Suppression Strategy Based on Supramolecular Host–Guest Interaction for High‐Performance Perovskite Solar Cells

Abstract The migration of multiple chemical species is are main factor leading to the intrinsic instability of perovskite solar cells (PSCs). Herein, a universal ion migration suppression strategy is innovatively reported to stabilize multiple functional layers by simultaneously suppressing the migration of multiple mobile chemical species based on host–guest interaction via calixarene supramolecules. After incorporating 4‐tert‐butylcalix[8]arene (C8A), the interfacial defects are passivated, suppressing trap‐assisted nonradiative recombination. Moreover, the p‐doping of Spiro‐OMeTAD is facilitated, and the extraction and transport of holes are promoted for n‐i‐p regular PSCs. The C8A doped regular devices based on the two‐step perovskite deposition method achieve a power conversion efficiency (PCE) of 26.01% (certified 25.68%), which is the record PCE ever reported for the TiO₂‐based planar PSCs. The C8A passivated p‐i‐n inverted PSCs obtain a champion PCE of 27.18% (certified 26.79%), which is the highest PCE for the PSCs using the vacuum flash evaporation method. The resulting unsealed inverted device retains 95% of its initial PCE after 1015 h of continuous operation at maximum power point. This work provides a feasible and effective avenue to address the intrinsic instability of perovskite‐based photovoltaics and other optoelectronic devices.