Non-ionic Phthalocyanine Additives Enable Synergistic Passivation and Strain Buffering in Stable Perovskite Solar Cells

The long-term stability of high-efficiency n-i-p perovskite solar cells is limited by coupled defect migration, residual lattice strain, and thermal–mechanical degradation. Here, we develop a non-ionic, interface-enriched zinc phthalocyanine derivative, 4PCSZnPc, as a molecular stabilizer for simultaneous defect anchoring and strain buffering. Unlike ionic additives that may introduce mobile species, 4PCSZnPc is distributed throughout the film, with enrichment near the buried SnO2/perovskite interface. Peripheral N/O/S heteroatoms coordinate with under-coordinated Pb2+ sites, while the Zn-regulated macrocyclic center interacts with iodide-related defects, forming dual-site Lewis acid–base anchoring. Meanwhile, the rigid phthalocyanine framework reduces residual tensile stress and may hinder strain-assisted ion migration. These combined effects of defect passivation and strain buffering reduce non-radiative recombination, improve film uniformity, and enhance thermal robustness. Consequently, 4PCSZnPc-treated devices achieve a champion power conversion efficiency (PCE) of 26.88% (certified 26.74%), a T80 lifetime of 1358 h under 1-sun at 85 °C, and 95% retention after 200 thermal cycles, providing a design principle for future thermally resilient photovoltaics.