Eindhoven: Improved solar cells

Development lead

Bram Hoex and colleagues at Eindhoven University of Technology and the Fraunhofer Institute for Solar Energy Systems in Freiburg, Germany, have improved the efficiency of a type of solar cell, n-type with front junction, from 21.9 to 23.2 per cent, a relative improvement of 6 per cent, by applying an ultra-thin aluminum oxide layer at the front of the cell.

While an improvement of just over 1 per cent in absolute terms may appear modest, it could enable solar cell manufacturers to greatly increase the performance of their products, as higher efficiency is an effective way of reducing the cost price of solar energy.

As the costs of applying the thin layer of aluminium oxide are expected to be low, the researchers say the development implies a significant reduction in the cost of producing solar electricity.

Hoex achieved the increase in efficiency by depositing an ultra-thin layer of approximately 30 nanometres of aluminium oxide on the front of a crystalline silicon solar cell that was fabricated by Jan Benick at Fraunhofer ISE.

This layer has an unprecedentedly high level of built-in negative charges, through which the normally significant energy losses at the surface of the cell are almost eliminated. Of all sunlight falling on these cells, 23.2 per cent is now converted into electrical energy.

A number of solar cell manufacturers have shown an interest in the technique.