Scientists from the University of Oxford’s Department of Physics have developed a revolutionary approach that could enable increasing amounts of solar electricity to be produced without the need for silicon-based solar panels. Their innovation consists of covering the surfaces of everyday objects such as backpacks, cars and cell phones with a new energy-generating material.
This new light-absorbing material is, for the first time, thin and flexible enough to be applied to the surface of almost any ordinary building or object. Thanks to a pioneering technique developed at Oxford, which consists of stacking several light-absorbing layers on a single solar cell, researchers have succeeded in exploiting a greater part of the light spectrum, making it possible to produce more energy from the same amount of sunlight.
This ultra-thin material, which uses the so-called “multi-junction” approach, has been certified by an independent body as offering an energy efficiency of more than 27%, matching for the first time the performance of traditional single-layer materials known as silicon photovoltaic cells. Japan’s National Institute of Advanced Industrial Science and Technology (AIST) granted the certification ahead of the researchers’ scientific study being published later this year.
“In just five years of experimenting with our multiple stacking or joining approach, we increased the energy conversion efficiency from around 6% to over 27%, which is close to the limits of what single-layer photovoltaic materials can achieve today,” said Dr Shuaifeng Hu, a postdoctoral researcher in the Department of Physics at the University of Oxford. “We believe that over time , this approach could allow photovoltaic devices to achieve much higher efficiencies, exceeding 45%.
For comparison, the energy efficiency of current solar panels is around 22% (meaning they convert around 22% of energy into sunlight), but the versatility of the new ultra-thin, flexible material is also a key element. At just over a micron thick, it is almost 150 times thinner than a silicon wafer. Unlike existing photovoltaic systems, which are typically applied to silicon panels, this material can be applied to almost any surface.
“By using new materials that can be applied as a coating, we have shown that we can replicate and outperform silicon, while gaining flexibility. This is important because it promises more solar power without needing so much silicon-based panels or purpose-built solar farms,” said Dr Junke Wang, a Marie Skłodowska Curie postdoctoral researcher at the Department of Physics at the University of Oxford.
The researchers believe their approach will continue to reduce the cost of solar energy and make it the most sustainable form of renewable energy. Since 2010, the global average cost of solar electricity has fallen by almost 90%, making it almost a third cheaper than electricity generated from fossil fuels. The innovations promise further cost reductions as new materials, such as thin-film perovskite, reduce the need for silicon panels and purpose-built solar farms.
“We can imagine perovskite coatings applied to larger types of surfaces to produce cheap solar power, like the roofs of cars and buildings, and even the backs of cell phones. If more solar power can be produced in this way, we can predict that in the long term there will be less need to use silicon panels or build more and more solar farms,” added Dr. Wang.
The researchers are part of a team of 40 scientists working on photovoltaics, led by Professor of Renewable Energy Henry Snaith from the Department of Physics at the University of Oxford. Their pioneering work in the field of photovoltaics, and in particular in the use of thin layer perovskite, began around ten years ago and benefits from a tailor-made robotic laboratory.
This work has strong commercial potential and has already begun to be applied in the utility, construction and automotive sectors. Oxford PV, a British company spun out of the physics department at the University of Oxford in 2010, whose co-founder and chief scientific officer, Henry Snaith, is on a mission to commercialize perovskite photovoltaic cells, recently began manufacturing large-scale production of perovskite photovoltaic cells at its factory in Brandenburg-an-der-Havel, near Berlin, Germany. This is the world’s first mass production line for “perovskite on silicon” tandem solar cells.
“We had first considered sites in the UK to begin manufacturing, but the government has not yet offered the same tax and trade incentives as elsewhere in Europe and the US,” Professor Snaith said . “Until now, the UK has looked at solar power only from the perspective of building new solar farms, but the real growth will come from commercializing innovations. We hope the new British Energy company will look into on this issue.”
“The latest innovations in solar materials and techniques demonstrated in our laboratories could become the platform for a new industry, manufacturing materials to generate solar energy more sustainably and economically using buildings, existing vehicles and objects,” added Professor Snaith. “The supply of these materials will be a new, fast-growing industry in the global green economy, and we have shown that the UK is innovating and leading the way scientifically. However, without new incentives and a better pathway to transforming this innovation into manufacturing, the UK will miss the opportunity to lead this new global industry,” Professor Snaith concluded.