Indium recycling pathways from heterojunction solar cells: Processes, challenges, and prospects

Indium is a vital raw material in heterojunction (HJT) solar cells, yet its limited reserves and increasing demand pose sustainability challenges. With the rapid growth of photovoltaic deployment, the secondary recovery of indium from end-of-life (EoL) HJT modules is becoming indispensable for resource security, economic value, and environmental protection. This review outlines the current status of indium recycling, integrating advanced pretreatment, selective leaching, and high-purity refining, while comparing their efficiency, environmental impact, and economic feasibility. Hydrometallurgical methods dominate current research, despite their prevalence, challenges regarding chemical consumption, hazardous emissions, and low recovery yields remain unresolved. Beyond technical barriers, weak regulatory frameworks and insufficient industrial-scale practices hinder efficient waste management. To ensure long-term sustainability, holistic recycling strategies should be integrated with policy incentives, eco-design of PV modules, and international cooperation. Advancing green recovery technologies that minimize secondary pollution and maximize material reuse is critical for foster a closed-loop supply chain for strategic critical metals. Overall, indium recovery from EoL HJT solar cells represents not only a technological challenge but also an opportunity to advance circular economy goals and support the sustainable development of renewable energy systems.