Interface-confined sulfidation metallurgy (ICSM): Sustainable recovery of high-purity Te/Cd/Sn and glass from EoL CdTe photovoltaics

CdTe thin-film solar cells, as a core component of photovoltaic devices, have been commercially deployed for over 30 years with global installations surpassing 30 GWp. Decommissioning has surged since 2010, showing major material recovery potential from retired modules. However, CdTe thin-film solar cells feature ultra-precise architectures with micron-sized CdTe/CdS/SnO 2 functional layers deposited on glass substrates. This structural complexity and ultralow metal concentrations create significant technical barriers for metal recovery. Current recycling technologies in both literature and practice exhibit insufficient constituent recovery and secondary waste generation, necessitating advanced separation technologies. This study developed an innovative recycling process achieving multi-component recovery: intact glass substrates, high-purity Te powder (99.9 wt%), CdS precipitates (99.0 wt%), and sodium thiostannate (Na 2 SnS 3 ) solutions. There were four steps: (1) Decommissioned modules were heated in air at 300 °C for 1 h to degrade EVA and recover intact back glass; (2) Front glass with functional layers further reacted with NaHS at 400 °C, converting CdTe/CdS/SnO₂ into Te/CdS/SnS₂ powder and recovering clean front glass; (3) Mixed powder was processed at 500 °C for 2 h (<10 Pa), yielding >99.9 wt% Te with 98.31 % ± 2.11 % recovery; (4) Na₂S leaching (140 g/L, L/S = 10:1, 40 °C, 2 h) yielded 99.0 wt% CdS precipitate and Na₂SnS₃ solution with >99 % metal recovery. Material balance analysis and life cycle assessment demonstrated that the proposed technology exhibits superior cost-effectiveness and minimized environmental footprint, while maintaining industrial scalability.