pH-Independent lead sequestration and light management enable sustainable and efficient perovskite photovoltaics

The illumination side of perovskite solar cells is more vulnerable to external impacts (such as hail, flying rocks, snow, hurricanes, etc.) than the rear side, leading to more likelihood of Pb²⁺ leakage. They also suffer from severe optical loss at the air/solid interface, deteriorating the solar cell performance. In this study, large-area textured phosphate-buffered functionalized polymer films (PFPFs) with self-healing characteristics, up to 16 × 16 cm² in size, are deliberately designed and employed on the illumination side of PSCs. The PFPF immobilizes Pb²⁺ mainly through phosphate precipitation with an ultrafast Pb²⁺ sequestration rate (200.9 m² min⁻¹ g⁻¹) and sequestration capacity equaling 24 times the theoretical Pb amount in typical 500-nm-thick PSCs. The pH-independent lead sequestration capability results in a Pb²⁺ leakage concentration well below the US drinking water safety level (15 μg L⁻¹) even under extreme environmental condition scenarios. The pyramidal-structured surface of the PFPF also reduces reflective losses over broadband wavelengths and increases the optical path of the incident light. We have utilized this in both rigid and flexible devices, improving the efficiencies by over 7% (relative gain). The PFPF is of low cost and can be easily applied to both rigid and flexible devices, demonstrating its universal applicability and promising commercialization potential.