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

Abstract

The illumination side of perovskite solar cells is more vulnerable to external impact (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-buffer functionalized polymer films (PFPF) with self-healing characteristics, up to 16 × 16 cm2 in size, are deliberately designed and employed on the illumination side of PSCs. 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 a typical 500-nm-thick PSCs. The pH-independent lead sequestration capability results in the Pb2+ leakage concentration well below the US drinking water safety level (15 μg/L) even under extreme environmental condition scenarios. The pyramidal-structured surface of PFPF also reduces reflective losses over broadband wavelengths and increases the optical path of incident light. We have utilized this in both rigid and flexible devices, improving the efficiencies by over 7% (relative gain). The PFPF is low-cost and can be easily applied to both rigid and flexible devices, demonstrating its universal applicability and promising commercialization potential.