A microwave radiation technology developed by researchers in Australia not only cuts the time and energy intensity of solar cell production but also yields devices that are more amenable to recycling.

The annealing process currently applied during silicon solar cell manufacture requires furnace temperatures of 1,652° F to 2,012° F (900° C to 1,100° C). The less energy intensive microwave radiation-based annealing scheme can selectively heat sections of a solar panel and mitigate light-induced degradation that can reduce cell efficiency by up to 10%.

Under microwave treatment, the ethylene vinyl acetate plastic coating that protects the silicon plate from moisture and contamination softens to the point where it can be peeled off mechanically. The plate can then be easily delaminated and its components reused without employing harsh chemicals.

The ability to focus microwave radiation means the heating induced can be selective and highly tuned, making the process ideal for fabricating heterojunction devices in which crystalline and amorphous silicon are interleaved. Precise focusing also means that annealing can be directed to specific parts of the solar panel, making it ideal for processing solar panels with more intricate internal structures fabricated for special purposes.

Tests demonstrated that absorption of microwaves in a semiconductor can be used as an effective annealing method, and this may provide many opportunities to reduce both cost and thermal load within the semiconductor industry.

The study conducted by researchers from Macquarie University and the University of New South Wales is published in Applied Physics Letters.