Clean Recovery of All Components of CIGS Thin-Film Solar Cells: Research on Ambient Temperature Oxidation Coupling Multimetal Cascade Extraction Process

As the copper indium gallium selenide (CIGS) solar cell industry expands, the recycling of its waste materials has become an essential requirement for achieving a circular economy. This study proposes an integrated clean process for recovering valuable metals from CIGS solar panels. The thermal alkali method (6% NaOH, 80 °C) can efficiently remove the PET coating (>98%) without damaging the underlying material. An innovative room-temperature, nonstirring HCl/H2O2 leaching process (7 M HCl, 5% v/v H2O2, 20 °C) synergistically extracts Cu, In, Ga, Se, Fe, Mo, and Ti through room-temperature oxidation and Ti passivation, with recovery efficiency exceeding 92.99% for each metal. A multistage solvent extraction system separates the leaching solution: TBP removes Fe/Mo (>99%) while minimizing coextraction of Ga/In; targeted TBP extraction enriches In (98.3%); D2EHPA extracts Ga (95.8%); LIX984 captures Cu at low pH (>99.9%). Se is recovered via a green ascorbic acid reduction method (99.5%). By combining the “stripping-leaching-extraction-reduction” process, the overall metal recovery efficiency exceeds 97%. After flocculation of the wastewater, the concentrations of all ions are below 5 ppm, meeting the requirements of the EU WEEE Directive and China’s circular economy standards. This closed-loop process provides key technology for establishing a sustainable “production-retirement-regeneration” chain in the photovoltaic industry.