ALD tool improves solar cells

Researchers have developed a thin-film coating providing an unparalleled level of surface passivation of crystalline silicon solar cells, using Oxford Instruments' FlexAL ALD tool.

The team from the Eindhoven University of Technology (TU/e), Netherlands, showed that ultra-thin aluminium oxide layers deposited by remote plasma ALD outperform existing passivation coatings in terms of eliminating the normally significant electronic losses at solar cells' back and front surfaces.

Oxford Instruments customised its FlexAL and OpAL tools for this specific application.

Improved solar cell efficiency was recently demonstrated in a collaboration between TU/e and the Fraunhofer Institute for Solar Energy Research (ISE) in Germany.

An efficiency of 23.2 per cent was obtained for Perl solar cells based on n-type silicon, with the application of an ultra-thin aluminium oxide layer at the front of the solar cell.

The p-type front of this class of solar cells was hard to passivate and the efficiency improvement of 6 per cent is therefore a significant advance.

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