# Rubber Additive Gives Perovskite Solar Its Missing 1,700 Hours - Date: 2026-03-31 - Category: Space & Aerospace A rubber vulcanization chemical helped perovskite-silicon tandem cells retain 91 percent efficiency after 1,700 hours of continuous operation — on industrial-grade TOPCon wafers, not bespoke lab cells. Whether it survives a summer on a rooftop in Arizona remains an open question. ---