Lead Leakage from Broken Perovskite Modules: Water-Soluble Lead and Lead Capture Layers

… more less Lead leakage from broken perovskite modules is the main safety worry about this technology. Most high-efficiency perovskites contain lead, and lead salts are toxic. In a working module the lead is sealed inside glass. If the glass cracks and rain gets in, the film breaks down into lead compounds such as lead iodide. These can dissolve in water and wash out. That makes them more mobile than the lead in old solder, which stays as metal. The amount is small. A square metre of panel holds well under a gram of lead, because the film is so thin. Still, mobile lead in soil or water is a real concern, so the package is designed to hold it in. One fix is a lead capture layer. This is a film or resin inside the package that binds lead tightly, often using phosphonate or sulfonate groups that grab lead ions. Tests on deliberately broken cells show these layers can hold back most of the lead. Some encapsulants also melt and reseal small cracks when warmed by the sun. At end of life, recycling can recover the lead and the glass. After this Concept you can explain why broken perovskite modules can leak lead and judge the fixes used to keep it in.