Simultaneous Suppression of Multilayer Ion Migration via Molecular Complexation Strategy toward High‐Performance Regular Perovskite Solar Cells

Abstract The migration and diffusion of Li + , I − and Ag impedes the realization of long‐term operationally stable perovskite solar cells (PSCs). Herein, we report a multifunctional and universal molecular complexation strategy to simultaneously stabilize hole transport layer (HTL), perovskite layer and Ag electrode by the suppression of Li + , I − and Ag migration via directly incorporating bis(2,4,6‐trichlorophenyl) oxalate (TCPO) into HTL. Meanwhile, TCPO co‐doping results in enhanced hole mobility of HTL, advantageous energy band alignment and mitigated interfacial defects, thereby leading to facilitated hole extraction and minimized nonradiative recombination losses. TCPO‐doped regular device achieves a peak power conversion efficiency (PCE) of 25.68 % (certified 25.59 %). The unencapsulated TCPO doped devices maintain over 90 % of their initial efficiencies after 730 h of continuous operation under one sun illumination, 2800 h of storage at 30 % relative humidity, and 1200 h of exposure to 65 °C, which represents one of the best stabilities reported for regular PSCs. This work provides a new approach to enhance the PCE and long‐term stability of PSCs by host–guest complexation strategy via rational design of multifunctional ligand molecules.