Composition Restoration Enables Recycling of Mixed‐Cation, Mixed‐Halide Perovskites for Solar Cells

The rapid industrial emergence of perovskite photovoltaics (PV) highlights their potential to complement silicon PV in meeting the growing global solar demand. As deployment scales, closed-loop recycling of perovskite PV will be beneficial to conserve critical resources and mitigate environmental risks associated with lead. However, mixed-cation, mixed-halide perovskites-typical in record-efficiency devices-undergo systematic composition drift during device fabrication. Consequently, material recovered from end-of-life modules inherits these deviations, degrading cell performance if reused without adjustment. To overcome this fundamental bottleneck in circular manufacturing, we developed a comprehensive quantification framework to audit and restore perovskite composition. By combining nuclear magnetic resonance (NMR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and ion chromatography (IC), we obtained full compositional fingerprints of the hybrid perovskite recovered from processed solar-cell stacks, allowing us to resolve their altered composition and restore the material to match the original precursor formulation. Composition restoration effectively closed the performance gap, yielding recycled perovskite cells with efficiencies comparable to pristine devices. A cost analysis demonstrates this approach can achieve a 69.1% cost reduction, while preserving supply-constrained elements like Cs and I. These results demonstrate a practical, compositionally informed pathway for the sustainable, closed-loop manufacturing of complex perovskite absorbers.