Precise Iodide-Trap Strategy for Photothermally Stable Spiro-OMeTAD-Based Perovskite Solar Cells

Photothermal stress induces irreversible iodide ion migration in perovskite solar cells (PVSCs) based on 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD). Diffused iodide ions lead to weak physical interfacial contact and de-doping of spiro-OMeTAD, posing substantial challenges to photothermal stability. Here we present a dual iodide-trap strategy to precisely trap mobile iodide ions, retaining high hole transport capacity in spiro-OMeTAD and robust interfacial stability under photothermal stress. Specifically, 2,3,5,6-tetrafluoro-4-iodobenzamide (TFIBA) is innovatively devised as an inhibitor to construct precise iodide ion traps on perovskite surfaces via directional halogen bonding. Moreover, (bis(trifluoroacetoxy)iodo)pentafluorobenzene (FPIFA) as an ideal dopant ensures rapid and controllable p-doping of spiro-OMeTAD without air assistance, with a byproduct providing an additional trap against iodide invasion. Consequently, the resulting device achieves an efficiency of 26.81% with T₉₃ lifetime over 1140 h under standard illumination at 85°C, representing one of the highest stabilities for spiro-OMeTAD-based PVSCs. These findings exhibit a viable route toward efficient and photothermally stable PVSCs for commercialization.