Toward Stable and Efficient Perovskite Solar Cells: Unlocking the Potential of Porous PbI ₂ Scaffolds via Two‐Step Sequential Deposition

ABSTRACT The two‐step sequential deposition method for perovskite solar cells (PSCs) is often limited by the dense PbI ₂ film morphology, leading to incomplete conversion, residual PbI ₂ , and high defect density. This review consolidates research showing that engineering a porous PbI ₂ architecture is a universal and transformative solution. We categorize the key strategies: (1) Solvent Engineering: Using solvent extraction, vapor treatment, or anti‐solvent methods to create rapid nanoporosity; (2) Molecular Additives: Lewis bases or volatile amines that coordinate with Pb ²⁺ , disrupting crystallization and forming porous scaffolds; (3) Ionic Liquids and Salts: Multi‐functional agents templating porosity while passivating defects and boosting stability; (4) Sacrificial Agents and Frameworks: Pore‐forming compounds or MOFs/COFs that provide predefined porous structures; (5) Interfacial Engineering: Substrate modifications or low‐dimensional seeds guiding favorable PbI ₂ porosity. A porous PbI ₂ scaffold enhances organic salt diffusion, ensuring complete conversion to high‐quality perovskite films with larger grains, improved crystallinity, and lower trap densities. This consistently yields PSCs with efficiencies >25%–26% and outstanding stability, often retaining >90% performance after thousands of hours. Controlling PbI ₂ morphology thus offers a scalable route to enhance perovskite photovoltaic performance and commercial viability.