Upcycling Silicon Photovoltaic Waste into Thermoelectrics

Two decades after the rapid expansion of photovoltaics, the number of solar panels reaching end-of-life is increasing. While precious metals such as silver and copper are usually recycled, silicon, which makes up the bulk of a solar cells, goes to landfills. This is due to the defect- and impurity-sensitive nature in most silicon-based technologies, rendering it uneconomical to purify waste silicon. Thermoelectrics represents a rare class of material in which defects and impurities can be engineered to enhance the performance. This is because of the majority-carrier nature, making it defect- and impurity-tolerant. Here, the upcycling of silicon from photovoltaic (PV) waste into thermoelectrics is enabled. This is done by doping 1% Ge and 4% P, which results in a figure of merit (zT) of 0.45 at 873 K, the highest among silicon-based thermoelectrics. The work represents an important piece of the puzzle in realizing a circular economy for photovoltaics and electronic waste.

Automated summary

With the increasing number of end-of-life solar panels, the recycling of precious metals like silver and copper has become common practice. However, the majority of the silicon used in solar cells ends up in landfills due to the difficulty and cost of purifying waste silicon. This research presents a breakthrough in upcycling silicon from photovoltaic waste into thermoelectric materials, offering potential for a circular economy for photovoltaics and electronic waste.