Sustainability Benefit Ratio: Bridging Environmental Metrics and Economic Feasibility for Circular Remanufacturing of Perovskite Solar Cells

Perovskite solar cells (PSCs) are approaching large-scale deployment, yet short lifetimes and end-of-life risks make circular strategies essential. Here we propose a time-resolved Sustainability Benefit Ratio (SBR), a dimensionless indicator that aggregates (i) physically accounted greenhouse-gas emissions/avoidance and (ii) monetized life-cycle costs converted to CO2-equivalent via an economic carbon-intensity coefficient (CC), enabling a unified assessment of environmental performance and economic burdens over time. This work highlights design for remanufacturing as a key enabler of circular PSC deployment. Using an industrially relevant carbon-based PSC architecture designed for remanufacturing, we simulate multi-cycle operation under periodic remanufacturing and repeated new manufacturing, and derive an analytic steady-state limit, SBRss. Remanufacturing markedly increases long-run circular value relative to renewal replacement under realistic lifetimes, while conventional payback economic indicators diverge in timing, motivating an explicit bridge between environmental payback and economic feasibility. We therefore introduce a circular value weighting factor β applied only to CC-converted terms, where β = 0 recovers a purely physical CO2-based benefit-to-burden ratio, and β-sweeps transparently represent stakeholder-dependent emphasis on valuation-weighted burdens/credits. Finally, feasibility-constrained design maps and Bayesian optimization demonstrate that SBRss can serve as a practical objective function to efficiently explore economically viable remanufacturing specifications and identify dominant design levers governing circular value.