A research team led by Kanazawa University has developed a one-step recycling strategy that enables the efficient recovery of toxic lead (Pb) and valuable metals, including gold (Au) and indium (In), from end-of-life flexible perovskite solar cells (PSCs).
Flexible PSCs are gaining strong attention due to their high efficiency, lightweight structure, and compatibility with low-cost, large-area manufacturing. However, their complex multilayer architectures - typically incorporating Pb-based perovskite absorbers, Au electrodes, and indium tin oxide (ITO) on polymer substrates - pose challenges for end-of-life treatment. In particular, the lack of efficient recovery routes for toxic Pb and scarce metals such as Au and In has limited the development of circular lifecycle strategies. To address this issue, the researchers designed an integrated process based on a low-concentration mixed acid dissolution system combined with selective adsorption and controlled precipitation. The approach uses a HCl/HNO3 mixture (1 M : 1 M) to dissolve encapsulated flexible PSC stacks in a single step, effectively breaking down complex device structures while avoiding the safety and environmental concerns associated with highly concentrated acids such as aqua regia.
Following dissolution, Au is selectively recovered under strongly acidic conditions using a cellulose-based adsorbent (DMC-2), achieving a recovery efficiency of 91.6%. Subsequent pH adjustment enables the selective separation of Pb and In via chelating resin treatment, resulting in near-complete recovery efficiencies of 99.7% for Pb and 100% for In. The process also incorporates precipitation of metal sulfates, facilitating straightforward separation and purification while minimizing secondary waste.
"We wanted to develop a practical recycling strategy that not only recovers toxic Pb but also captures valuable metals including Au and In from end-of-life flexible PSCs and modules," explains Shahiduzzaman, associate professor at Kanazawa University and corresponding author of the study.
A key advantage of the method is its compatibility with both fresh and degraded devices, which is essential for real-world recycling scenarios. In addition, the system supports regeneration of the chelating resins and reduces secondary waste generation, improving the environmental footprint of the process. The combination of selective adsorption and controlled chemical conditions enables high recovery selectivity without requiring complex multi-step separations.
The resulting closed-loop recycling pathway provides both environmental and economic benefits by mitigating Pb-related risks while recovering critical raw materials. This is particularly important given the growing demand for Au and In in electronic and energy technologies, as well as increasing regulatory pressure around Pb-containing devices.
"Recycling technologies will become increasingly important as PSCs move closer to large-scale commercialization," Kanazawa University Prof. Tetsuya Taima says. "Our work provides a pathway toward a circular economy for next-generation perovskite solar energy technologies."
The researchers note that the proposed strategy can be integrated into existing photovoltaic recycling infrastructures and scaled with further optimization. Future work will focus on process scale-up, operational parameter refinement, and life-cycle assessment to enhance overall sustainability and industrial feasibility.
Overall, the study demonstrates a viable and scalable route to recover toxic and valuable components from flexible PSCs, supporting resource security and the circular deployment of emerging perovskite photovoltaic technologies.
