Can be mounted anywhere

Flexible solar cell with high efficiency unveiled

Shuaifeng Hu with the new perovskite-based solar cell

(Bild: Martin Small)

Scientists at Oxford University have developed a new tandem solar cell based on perovskites that is thin and flexible enough to be attached to almost any surface, according to a statement from the university. The new solar cell is said to be more efficient than current silicon-based cells.

For the first time, the new material is thin and flexible enough to be applied to the surface of almost any building or common object, the university said in a statement. The technology developed, in which several light-absorbing layers are stacked in a solar cell, has also made it possible to utilize a larger range of the light spectrum so that more electricity can be generated from the same amount of sunlight.

The ultra-thin material has been independently certified to have an energy efficiency of over 27 percent, matching the performance of conventional, single-layer, energy-generating materials known as silicon photovoltaics for the first time. The Japanese National Institute of Advanced Industrial Science and Technology (AIST) granted the certification ahead of the publication of the researchers' scientific study later this year.

Efficiency of 45 percent possible
"In just five years of experimenting with our stacking or multi-junction approach, we have been able to increase the energy conversion efficiency from about six percent to over 27 percent, which is close to the limit of what single-layer photovoltaics can achieve today," said Dr. Shuaifeng Hu, a post-doctoral researcher at Oxford University Physics. "We believe that this approach can achieve much higher efficiencies of over 45 percent over time."

In comparison, the efficiency of today's solar panels is around 22 percent, according to the university. However, the versatility of the new, ultra-thin and flexible material is also crucial: with a thickness of just over one micrometer, it is almost 150 times thinner than a silicon wafer. In contrast to conventional photovoltaics, which are usually applied to silicon plates, this material can therefore be applied to almost any surface.

"Cheap solar power"
The researchers believe that their approach will further reduce the cost of solar energy and make it the most sustainable form of renewable energy. Since 2010, the global average cost of solar power has fallen by almost 90 percent, making it almost a third cheaper than electricity generated from fossil fuels. Innovation promises further cost savings as new materials such as thin-film perovskite reduce the need for silicon panels and purpose-built solar farms.

"We can imagine perovskite coatings being applied to a variety of surfaces to generate cheap solar power, for example on the roof of cars and buildings and even on the back of cell phones. If more solar energy can be generated in this way, we will need to use fewer silicon panels or build more and more solar farms in the longer term," Dr. Wang added.