New solar cell enters space for the first time

German researchers have for the first time sent a perovskite and organic solar cell into space on a rocket. The solar cell withstood the extreme conditions in space and generates energy from direct sunlight and light reflected from the Earth's surface.

The research, published recently in Joule, lays the foundation for future near-Earth applications and potential deep space missions.

One of the goals of space missions is to minimize the weight of equipment carried on rockets. While the inorganic silicon solar panels currently used in space missions and satellites are highly efficient, they are very bulky and rigid.

Hybrid perovskite and organic solar cells, an emerging technology, are ideal candidates for future applications due to their incredible lightness and flexibility.

"In this industry, what matters is not the efficiency, but the amount of electrical energy produced per unit of weight, the so-called specific power," said senior author Peter Müller-Buschbaum of the Technical University of Munich. "During the rocket flight, the new solar cell achieved a power of 7 to 14 mW/cm2."

"If you transfer one kilogram of solar cells onto an ultra-thin foil, you can cover an area of ​​more than 200 square meters and generate enough electricity to power 300 standard 100-watt light bulbs. This is more than 10 times more than existing technology," said Lennart Reb, lead author of the study from the Technical University of Munich.

In June 2019, the rocket was launched in northern Sweden, entered space and reached an altitude of 240 kilometers. The perovskite and organic solar cells located on the payload successfully withstood the extreme conditions of the rocket flight - from the rumble and high temperature at launch to the strong ultraviolet rays and ultra-high vacuum in space. "The rocket launch is a big step, and riding a rocket is really like entering a different world." Reb said.

In addition to working efficiently in space, perovskite and organic solar cells can also operate in low-light conditions. When there is no direct light, traditional solar cells usually stop working and the power output becomes zero.

However, the team found that even without direct exposure to sunlight, weak diffuse light reflected from the Earth's surface can increase the energy output of perovskite and organic solar cells.

"That's a good hint and confirmation that this technology could be used for so-called deep space missions, where you send them out into space far away from the sun, where standard solar cells won't work," Müller-Buschbaum said. "It's really exciting about the future of this technology, to be able to use these solar cells for more space missions in the future."

But before launching more new solar cells into space, Müller-Buschbaum said one of the limitations of this research is the short time the rocket spent in space - just seven minutes total.

The next step is long-term applications in space, such as use on satellites, to understand the battery's lifetime, long-term stability and full potential.

"This is the first time that perovskite and organic solar cells have been sent into space, which is a milestone," says Müller-Buschbaum. "This paves the way for more applications of such solar cells in space. In the long term, this may also help to make these technologies more widely available in our terrestrial environment."