Honeycomb layer boost for ultra-thin silicon photovoltaics

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Researchers have developed a light-trapping honeycomb layer that has improved energy absorption in ultra-thin silicon photovoltaic panels by 25 per cent.

honeycomb layer
The thin silicon membrane uses a disordered honeycomb layer to maximise the absorption of sunlight (Image: Surrey University)

Co-led by Surrey University, the team’s 1μm thick solar panels convert light into electricity more efficiently than others and could pave the way to make it easier to general more clean, green energy.

In a paper published in Photonics, the team detail how they used characteristics of sunlight to design a disordered honeycomb layer which lies on top of a wafer of silicon. The honeycomb design enables light absorption from any angle and traps light inside the solar cell, enabling more energy to be generated.

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In a statement, Dr Marian Florescu from Surrey University’s Advanced Technology Institute (ATI) said: “One of the challenges of working with silicon is that nearly a third of light bounces straight off it without being absorbed and the energy harnessed. A textured layer across the silicon helps tackle this and our disordered, yet hyperuniform, honeycomb design is particularly successful.”

The team of researchers from Surrey University and Imperial College London worked with AMOLF in Amsterdam to design, model and create the new ultra-thin photovoltaic.

In the laboratory, they are said to have achieved absorption rates of 26.3mA/cm2, a 25 per cent increase on the previous record of 19.72mA/cm2 achieved in 2017. They secured an efficiency of 21 per cent but anticipate that further improvements will push the figure higher.

“There’s enormous potential for using ultra-thin photovoltaics,” said Dr Florescu. “For example, given how light they are, they will be particularly useful in space and could make new extra-terrestrial projects viable. Since they use so much less silicon, we are hoping there will be cost savings here on Earth as well, plus there could be potential to bring more benefits from the Internet of Things and to create zero-energy buildings powered locally.”

The team’s findings could also benefit industries where light management and surface engineering are crucial, such as in photo-electrochemistry, solid-state light emission and photodetectors.

Next steps for the team will include investigating commercial partners and developing manufacturing techniques.