Pulse laser recovery of high-purity colloidal silver spheres from end-of-life crystalline silicon solar panels

Abstract

Crystalline silicon photovoltaic (c-Si PV) modules, regarded as first-generation solar cells, are expected to generate a significant volume of end-of-life materials in the coming years due to their limited lifecycle. We propose a novel recycling process to recover silver from spent c-Si PV modules, producing high-purity silver spheres through photoreduction using a nanosecond pulsed laser. In detail, a leaching efficiency of ∼100 % was shown with an optimized lixiviant concentration (1 M HNO3), temperature (70 °C), time (60 min), and solid–liquid ratio (75 g/L). To recover high-purity silver from the leachate, interfering ions other than silver were removed through pH adjustment, and the loss rate of silver was only 1.9 %. High-purity spherical silver particles were recovered by irradiation with a nanosecond pulsed laser at 100 mJ for 60 min to the Ag2O suspension, which was produced by adding NaOH to the purified leachate. The final recovery efficiency of silver was ∼ 98 % through leaching, impurity removal, and laser reduction from the waste PV cell. A preliminary life cycle assessment indicated that the process has lower energy consumption and environmental impact than conventional techniques, though economic performance still requires improvement.