Structural and functional engineering strategies for long-term stability of lead halide perovskite solar cells

Lead halide perovskite solar cells (LHPSCs) have achieved outstanding power conversion efficiencies, yet their long-term operational stability remains the primary barrier to commercialisation. Device degradation arises from both intrinsic factors like ion migration, light-induced phase segregation, and crystallographic instabilities, and extrinsic stressors such as moisture, oxygen, thermal stress, ultraviolet radiation, and electrical bias. These mechanisms collectively accelerate perovskite decomposition, interfacial deterioration, and electrode corrosion, ultimately reducing device efficiency and operational lifespan. To systematically address these challenges, this review critically examines engineering strategies across multiple structural and functional levels. Bulk compositional modification and defect passivation improve intrinsic material stability and suppress ion migration. Surface and interface passivation enhances energy-level alignment while reducing non-radiative recombination losses. Charge transport layer optimisation ensures effective carrier extraction and improved thermal resilience, while electrode engineering mitigates metal diffusion and chemically induced deterioration. Finally, we outline future directions centred on stability-by-design principles, integrating advanced materials and interface engineering, robust encapsulation, operando characterisation, and artificial intelligence and machine learning-driven optimisation to overcome key degradation pathways and enable long-lasting, high-performance LHPSCs.