Internal electric field design suppresses ion migration in perovskite solar cells

Halide ion migration is one of the most critical bottlenecks preventing the commercial deployment of perovskite solar cells (PSCs). Current mainstream strategies, relying solely on material-level defect passivation or physical barriers, remain insufficient to prevent the accumulation and penetration of activated ions during long-term operation. Here, we propose a physical paradigm, the ion blocking contact (IBC), that significantly suppresses ion migration via interfacial built-in electric field engineering. By constructing a targeted p-type ion blocking contact at hole transport layer (HTL) side, the dual-functional contact generates an electric field to repel ion migration, and simultaneously acts as a physical barrier to further enhance ion blocking. We validate this conceptual design across both n-i-p and p-i-n device architectures by employing strategies tailored to their distinct processing compatibilities. This strategy enables independently certified power conversion efficiencies of 26.29% and 27.05% for n-i-p and p-i-n architectures, respectively. Crucially, both IBC devices exhibit superior operational stability under 85°C maximum power point tracking, with the n-i-p and p-i-n devices showing less than 3% and 2% efficiency loss after 1200 and 2160 hours, respectively.