Cryogenic grinding for selective lead separation in Film-Type perovskite solar cell waste

The increasing development of perovskite solar cells (PSCs) has raised concerns regarding end-of-life management due to the presence of lead (Pb) in the perovskite absorber layer. Film-type PSC modules consist of thin inorganic functional layers laminated within polymer-rich structures, making mechanical separation difficult. This study investigates cryogenic grinding combined with particle size classification as a management strategy for PSC waste. Cryogenic grinding using dry ice was employed to suppress polymer softening and promote brittle fragmentation of the laminated structure.　Macroscopic and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) observations revealed stepwise fragmentation behavior during cryogenic milling. Polymer-based laminated outer films were readily delaminated, exposing the underlying functional layers. Subsequently, the metal back electrode and the perovskite absorber layer were selectively fragmented into fine composite particles, whereas polyethylene terephthalate (PET)-supported conductive substrate layers containing In (indium) and Sn (tin) remained relatively coarse. Elemental redistribution analysis demonstrated strong concentration of metal electrode derived material and Pb into the < 0.5 mm fraction. Under optimized conditions using an impact-type cutter with a milling duration of 20 s, 86% of metal electrode derived material was concentrated into the < 0.5 mm fraction. Leaching tests showed that Pb release was primarily associated with the fine particle fraction, whereas several coarse fractions exhibited low Pb concentrations. These results demonstrate that cryogenic grinding can selectively concentrate Pb-bearing functional layers into a limited material stream, providing a potential upstream separation process for PSC waste management.