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

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.