Electrochemically Enabled Recycling of Cadmium Telluride Photovoltaic Solar Panels for Extracting Critical Semiconductor Materials

Abstract Global transition to clean energy security requires technologies that efficiently gather the potential of renewable sources but also the conception of cradle-to-cradle approaches that close the materials loop, supporting the sustainability of such technologies. Within the realm of solar energy, cadmium telluride (CdTe) thin-film photovoltaics (PVs) occupy >30% of the U.S. utility-scale solar panel market. However, due to limited resources of Te and toxicity of Cd, recovery of Te and Cd from end-of-life (EOL) CdTe PVs remains a critical step of the overall technology viability. Current industrial recycling technologies for EOL CdTe PVs are highly energy- and chemical-intensive processes and require the sacrificial use of hydrogen peroxide (H2O2), embedding high carbon footprint. To improve the energy efficiency and environmental sustainability of chemical recycling of EOL CdTe PVs, herein we have developed a novel electrochemically (EC)-enabled recycling strategy. EC-enabled recycling precludes externally sourced H2O2, and, instead, leverages H2O2 that is generated onsite, in situ from oxygen using electrons as ‘green reagents’. The superior performance of EC-enabled recycling allowed near-quantitative (∼99%) extraction efficiencies for Te and Cd, while reducing >65% of the total process energy consumption of conventional chemical recycling. Techno-economic and life cycle analyses helped identify the economic and environmental hotspots with which to further improve practical viability. Application of EC recycling for energy-efficient extraction of Te and Cd from EOL CdTe PVs constitutes the first example in the field, supporting resilient and sustainable supply chains of critical energy metals to produce new solar panels, facilitating the global ‘net-zero carbon’ mission.