Scientists at Oxford University Physics Department have innovated a new approach to generating solar electricity without the need for silicon-based solar panels.

An ultra-thin layer of a power-generating material called perovskite can be applied on the surface of everyday objects including rucksacks, cars, and mobile phones, turning them into solar panels.

The light-absorbing material is thin and flexible enough to be coated onto the surface of those objects, and the scientists claim to have developed a pioneering technique which stacks multiple light-absorbing layers of perovskite that are just over one micron thick into one solar cell. It is almost 150 times thinner than a silicon wafer.

The scientists have even had the material and stacking technology independently certified by Japan’s National Institute of Advanced Industrial Science and Technology (AIST).

This material using the multi-junction or stacking approach has now been independently certified to deliver over 27 per cent energy efficiency – for the first time matching the performance of traditional, single-layer, energy-generating materials known as silicon photovoltaics.

“During just five years experimenting with our stacking or multi-junction approach we have raised power conversion efficiency from around 6 per cent to over 27 per cent, close to the limits of what single-layer photovoltaics can achieve today,” said Dr Shuaifeng Hu, Post Doctoral Fellow at Oxford University Physics. “We believe that, over time, this approach could enable the photovoltaic devices to achieve far greater efficiencies, exceeding 45 per cent.”

Solar panels today have around a 22 per cent energy efficiency – meaning they convert around 22 per cent of the energy in sunlight.

While existing photovoltaics are generally applied to silicon panels, this new material can be applied to almost any surface as a coating.

“By using new materials which can be applied as a coating, we’ve shown we can replicate and outperform silicon whilst also gaining flexibility. This is important because it promises more solar power without the need for so many silicon-based panels or specially-built solar farms,” said Dr Junke Wang, Marie Skłodowska Curie Actions Postdoc Fellow at Oxford University Physics.

The researchers have indicated that the new innovation could reduce the cost of solar power. Since 2010, the global average cost of solar electricity has fallen by almost 90 per cent, making it almost a third cheaper than that generated from fossil fuels.

“We can envisage perovskite coatings being applied to broader types of surface to generate cheap solar power, such as the roof of cars and buildings and even the backs of mobile phones. If more solar energy can be generated in this way, we can foresee less need in the longer term to use silicon panels or build more and more solar farms,” added Dr Wang.

The next step would be to explore commercial applications of the stacking technology. Oxford PV, a UK company spun out of Oxford University Physics in 2010 by co-founder and chief scientific officer Professor Henry Snaith to commercialise perovskite photovoltaics, recently started large-scale manufacturing of perovskite photovoltaics at its factory in Brandenburg-an-der-Havel, near Berlin, Germany. This is the world’s first volume manufacturing line for ‘perovskite-on-silicon’ tandem solar cells.