Efficiency record for black silicon solar cells jumps to 22.1 percent

Aalto University's researchers improved their previous record by over 3 absolute percents

20-May-2015 - Finland

The researchers from Finland's Aalto University and Universitat Politècnica de Catalunya have obtained the record-breaking efficiency of 22.1% on nanostructured silicon solar cells as certified by Fraunhofer ISE CalLab. An almost 4% absolute increase to their previous record is achieved by applying a thin passivating film on the nanostructures by atomic layer deposition, and by integrating all metal contacts on the back side of the cell.

Aalto University

The surface area of the best cells in the study was already 9 cm2. This is a good starting point for upscaling the results to full wafers and all the way to the industrial scale.

The surface recombination has long been the bottleneck of black silicon solar cells and has so far limited the cell efficiencies to only modest values. The new record cells consists of a thick back-contacted structure that is known to be highly sensitive to the front surface recombination. The certified external quantum efficiency of 96% at 300nm wavelength demonstrates that the increased surface recombination problem no longer exists and for the first time the black silicon is not limiting the final energy conversion efficiency. The results were published in Nature Nanotechnology.

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