Energy & Green Tech

The efficient annealing of silicon using microwave radiation for the production of solar cells

Solar cells will be easier to recycle, and their manufacturing process will be enhanced by a microwave technology developed at Macquarie University.

During solar panel manufacturing, silicon undergoes annealing, a series of high-temperature processes. The cells are currently cooking in an oven.

However, a team led by senior lecturer Dr. Binesh Puthen Veettil from the School of Engineering demonstrated that heating with microwave radiation is nearly as effective in a paper that was published this week in the journal Applied Physics Letters. In addition, it offers additional benefits and conserves a lot of time and effort.

Silicon is selectively heated by microwave radiation, which results in almost instantaneous effects and significant energy savings. This is in part due to the fact that the remaining glass, plastic, and aluminum laminated panels are largely unaffected. And that property, for which the group has a patent application pending, has resulted in an unexpected recycling benefit.

“In the rare cases when they are recycled, the panels are crushed, heated to around 1400°C, and then chemically washed to remove the plastic—a process that uses a lot of energy. However, governments are demanding that solar panels be recycled as they reach the end of their useful lives and are retired. Solar panels first started to be deployed in large numbers about 20 to 30 years ago.”

Dr. Binesh Puthen Veettil of the School of Engineering.

Benefits of recycling During microwave treatment, the silicon plate’s plastic (ethylene vinyl acetate) coating softens to the point where it can be mechanically peeled off. This protects the silicon plate from moisture and contamination. This indicates that no harsh chemicals are required to delaminate the plate and reuse its components.

Dr. Veettil asserts, “Until now, it made economic sense to simply dump the panels in the landfill.” In the uncommon occurrences when they are reused, you pound the boards, heat them to around 1400°C, and wash them with synthetics to eliminate the plasticpoa profoundly energy-requesting process. However, governments are now requesting that the solar panels, which were installed in large numbers between 20 and 30, be recycled as they reach the end of their useful lives and are being decommissioned.

Microwave annealing has a number of additional advantages over selective annealing. The capacity to concentrate microwave radiation implies the warming it incites can be particularly and exceptionally tuned. For instance, heterojunction technology, in which crystalline and amorphous silicon are interleaved, is utilized in some of the more recent panels. Faster and better-directed annealing is extremely beneficial in these cells.

Exact centering likewise implies that strengthening can be coordinated to explicit pieces of the sunlight-based charger, making it ideal for tempering sunlight-powered chargers with additional mind-boggling inner designs created for specific purposes.

In addition, microwave annealing takes place in a clean environment, in contrast to an oven, where various chemical substances are released from the walls. Dr. Veettil explains, “So there is less contamination.” What’s more, the entire interaction can be generally enjoyed at room temperature.”

New materials Macquarie is working on a number of other projects that involve solar cells and sustainable energy. Associate Professor Shujuan Huang is in charge of a group studying microwave annealing in perovskite solar cells. He is one of the co-authors of the annealing paper. Perovskites are a gathering of glasslike minerals with semiconductor properties that may, in the future, be utilized for sun-based cells since they are adaptable, lightweight, and modestly priced to create.

Compared to conventional annealing methods, microwave radiation produced more efficient solar cells in this instance, but the reason for this is unclear. This work is being done in part to find out the answer to that question.

More information: Binesh Puthen Veettil et al, Microwave annealing of silicon solar cells, Applied Physics Letters (2023). DOI: 10.1063/5.0127896

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