29th September 2013

World record solar cell with 44.7% efficiency

The efficiency of solar power continues to inch upward.

Two German institutes – Fraunhofer ISE and Helmholtz-Zentrum Berlin – collaborated on a three year project, setting a new world record. Their work involved creating four subcells, based on different materials stacked on top of each other, each absorbing separate parts of the spectrum and combining these wavelengths to increase the overall power.

Solar efficiency is defined as the percentage of sunlight hitting a panel – from infrared through to ultraviolet – that is successfully converted to electricity. The researchers' new cell achieved an efficiency of 44.7%, a full percentage point higher than a previous effort by the same team just four months ago.

Frank Dimroth, project leader at Fraunhofer ISE, states in a press release: “We are incredibly proud of our team which has been working now for three years on this four-junction solar cell. This four-junction solar cell contains our collected expertise in this area over many years. Besides improved materials and optimisation of the structure, a new procedure called wafer bonding plays a central role. With this new technology, we are able to connect two semiconductor crystals, which otherwise cannot be grown on top of each other with high crystal quality. In this way we can produce the optimal semiconductor combination to create the highest efficiency solar cells.”

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