A Simple Green Process to Recycle Si from Crystalline-Si Solar Cells

Solar-grade Si can be recycled from end-of-life crystalline-Si solar cells and this recycled Si can be a new feedstock for growth of Si ingots. This study focuses on removing heavily-doped layers from crystalline-Si solar cells and extracting the Si base for recycling. The solar cells used in the study are commercial cells without the front Ag electrode. It is demonstrated that the heavily-doped layers can be removed within 30 min at 50 degrees C, and over 90% of the Si in the original cells can be recovered. Our method is simple and green, involving only three chemicals, HCl, HF and NaOH. In addition, a technique to monitor the removal of the heavily-doped layers based on four-oint probe is illustrated.