The cell boasts high energy efficiency with further increases possible

Solar cell efficiency rockets with stacking technology

Scientists at Laboratory for Thin Films and Photovoltaics in Switzerland have created a super energy-efficient dual-layer solar cell.

Two solar cells were stacked on top of one another, with the top layer being constructed from semi-transparent material.

While the top layer was able to efficiently convert large energy photons into electricity, the underlying cell was able to convert the remaining low-energy photons.

Greater energy efficiency was achieved because a larger portion of the light energy was able to be converted to electricity than with traditional technology.

Although similar techniques have been employed for some time, the high cost of creating tandem cells on expensive single crystal wafers prevented the technology from being mass produced and it was confined to niche uses such as space vehicles.

However, the tandem cells from the Swiss researchers are developed on polycrystalline thin films which make them suitable for large area, low-cost manufacturing. Flexible plastic or metal foils could also be used as substrate in the future.

The tandem solar cell has already yielded an efficiency rate of 20.5 per cent when converting light to electricity and the researchers have emphasised that it has the potential to offer better conversion rates in the future.

They believe that a 30 per cent efficient cell is possible although further research will be needed to reach this level of electricity production.

"What we have achieved now is just the beginning. We will have to overcome many obstacles before reaching this ambitious goal,” said.Ayodhya Tiwari, the head of the laboratory.

“To do this, we will need lots of interdisciplinary experience and a large number of combinatorial experiments until we have found a semi-transparent high-performance cell together with the right base cell and technologies for electrical interconnections of these solar cells."

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