A 15.6 cm × 15.6 cm versatile SHJ photo voltaic cell
Picture: Chinese language Academy of Sciences, nature, Inventive Commons License CC BY 4.0
Researchers on the Chinese language Academy of Sciences have efficiently developed foldable crystalline silicon (c-Si) wafers, identified for his or her robust light-harvesting functionality, to be used in versatile silicon heterojunction (HJT) photo voltaic cells.
Scientists say that HJT cell expertise is good for making versatile photo voltaic cells, as a result of it eliminates blade warping as a result of inner stress in the course of the firing course of. The wafers are produced utilizing a blunting therapy, a method generally used to spherical the sides of a wafer, to forestall flashing and cracking throughout processing. The researchers stated that the therapy resulted in a shift within the fracture mechanism from intrinsic brittle cleavage fracture to shear banding with steps and cracks.
The analysis staff used 180 μm Czochralski n-type c-Si wafers, equipped by China-based Sichuan Yongxiang, to provide textured wafers with a thickness of 60 μm.
“The wafers had been textured with a 2.1-vol% aqueous alkali answer at 80 C for 10 min to kind microscale pyramids on the surfaces,” it defined. “All wafers are cleaned utilizing an ordinary root trigger evaluation (RCA) course of to take away natural and metallic ions. Subsequent, they had been cleaned with a 2.0% aqueous answer of hydrofluoric acid for 3 minutes to etch the floor oxide.
The teachers used the wafers to make two HJT cells with thicknesses of 65 μm and 55 μm. The primary cell has an influence conversion effectivity of 23.31%, an open-circuit voltage of 0.752 V, a short-circuit present density of 0.09 mA cm-2, and a fill issue of 82.40%. The second cell achieved an effectivity of 23.35%, an open-circuit voltage of 0.754 V, a short-circuit present density of 0.11 mA cm-2and a fill issue of 82.51%.
The group then utilized an anti-reflective coating based mostly on magnesium fluoride (MgF2) to the cells and their effectivity was elevated to 24.50%.
“Though this worth is decrease than (25.83%) of a thick cell as a result of it’s affected by the low gentle harvesting means of the thinner wafer, it’s a exceptional effectivity in comparison with the present versatile photo voltaic cells produced from different cost-effective supplies,” the scientists stated, noting that utilizing a 60-μm wafer would scale back manufacturing prices by roughly 29%. “Total, the versatile expertise developed on this examine reduces the vitality price degree by roughly 39% (23%) on the photo voltaic cell (module) degree.
Teachers current a brand new manufacturing course of for “Versatile photo voltaic cells based mostly on foldable silicon wafers with blunted edges,” just lately printed in NATURE. The analysis staff contains scientists from Tongwei (TW) in China, Changsha College of Science and Know-how, Southwest Petroleum College, Soochow College, and Beihang College,
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