Enhanced solar cells

A large-area solar cell with 18.4 per cent conversion efficiency and copper-plated contacts was recently developed by researchers in Belgium.

The team from the Leuven-based nano-electronics and nanotechnology research centre, IMEC, recently demonstrated the cells at the European Photovoltaic Solar Energy Conference in Hamburg, Germany.

The IMEC solar cell is designed with an emitter that has an enhanced response to blue wavelength light.

A solar cell’s emitter is a light-sensitive material used to emit electrons into a semiconductor and initiate the flow of electricity. The emitter's extra sensitivity to blue wavelength light means it will be capable of emitting more electrons and increasing the flow of electricity.

The researchers designed the cell with front contacts made of copper plating, and created cells measuring 125cm², which they believe proves the industrial viability of the process.

‘Using copper instead of silver adds to the sustainability of solar-cell production,’ said Joachim John, team manager at IMEC. ‘IMEC was able to do this because it has extensive experience with copper plating on silicon.

‘A similar efficiency result was obtained with screen-printed contacts, but the long-term sustainability and low-cost potential of copper-based contacting solutions and the fact that this was a first result obtained without dedicated fine tuning makes it particularly encouraging.’

Jef Poortmans, IMEC’s photovoltaics programme director, stated that the cells with copper-plated contacts are furthering IMEC’s goal to develop more cost-effective, efficient crystalline silicon solar cells. The ultimate goal, he added, is to target cells that are only 40µm thick with efficiencies above 20 per cent.