Facilitated Diffusion of Organic Ammonium Salts via OD-Induced Porous PbI2 for Efficient Two-Step Inverted Perovskite Solar Cells

• • Introduction of 2,4-oxazolidinedione (OD) into PbI2 precursor induces a porous PbI2 network, enhancing organic ammonium salt diffusion and reducing unreacted PbI2 residues, leading to a champion PCE of 26.31% (VOC 1.197 V, JSC 26.28 mA cm-2, FF 83.58%). • • The porous PbI2 framework and OD synergistically retard perovskite crystallization, yielding films with improved crystallinity and preferred orientation, which is critical for minimizing non-radiative recombination and enhancing charge extraction. • • Optimized devices exhibit negligible hysteresis and outstanding operational stability: retaining 90.24% of initial PCE after 1500 h at 25°C and 90.47% after 1000 h at 65°C under maximum power point tracking, demonstrating industrial relevance for long-term deployment. • • The approach directly addresses the bottleneck of incomplete conversion in two-step sequential deposition, offering a scalable route to high-efficiency inverted PSCs without complex processing steps.