New So­lar Cells for Space Tested on Suborbital Flight

MUNICH, Germany (DLR PR) — Almost all satellites are powered by solar cells – but solar cells are heavy. While conventional high-performance cells reach up to three watts of electricity per gram, perovskite and organic hybrid cells could provide up to 10 times that amount.

A research team from the Technical University of Munich (TUM) and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) has now tested this type of cell in space for the first time.

Perovskite and organic solar cells are promising options for future generations of solar cells. In recent years, their efficiency has rapidly caught up with that of conventional silicon-based cells. “The best perovskite solar cells currently achieve efficiency levels of 25 percent,” says Peter Müller-Buschbaum, Professor of Functional Materials at the TUM Department of Physics. “These thin solar cells, less than one micrometre thick, applied to ultra-thin, flexible synthetic sheets, are extremely lightweight. They can therefore produce nearly 30 watts per gram.”

Manufacture at room temperature

This is only possible thanks to a decisive advantage of the new solar cells: production of silicon solar cells requires very high temperatures and elaborate processes. Perovskite cells and organic semiconductors, on the other hand, can be manufactured at room temperature from solution.

“These organic solutions are very easy to process,” explains the lead author Lennart Reb. “Thus, the technologies open up new fields of application in which conventional solar cells were simply too unwieldy or too heavy – and that also applies far beyond the aerospace sector.”

Test flight into space

Two different types of organic and perovskite solar cells were tested in space for the first time on a research flight as part of the MAPHEUS 8 programme at the European Space and Sounding Rocket Range in Kiruna, Sweden. The rocket reached a height of nearly 240 kilometres.

“Our MAPHEUS programme allows us to rapidly implement experiments in a microgravity environment, offering exciting research findings,” says Andreas Meyer, co-author and Head of the DLR Institute of Materials Physics in Space. “This time it went particularly quick: it took us less than a year to progress from the initial idea to the maiden flight of the solar cells as part of the MAPHEUS 8 programme.”

Power generation under exceptional conditions

“Electrical measurements during the flight and the evaluation after recovery of the rocket showed that perovskite and organic solar cells can achieve their potential in terms of expected performance in orbit height,” reports Müller-Buschbaum. “Our measurements are therefore of great scientific value.”

The solar cells also generated electrical energy under diffuse incidence of light. “Cells turned away from the sunlight, which received only sparse lighting exclusively from Earth during the flight, still supplied electricity,” says Reb.

Due to being much thinner, the new solar cells could therefore also be used in much dimmer light, for example on missions to the outer Solar System where solar radiation is too weak for conventional space solar cells.

According to DLR materials scientist Andreas Meyer, “it would not be the first time that innovations are first established as space technologies but go on to be used around the world in other sectors. One reason for this is probably the very strict requirements that space places on all technical components.”