German researchers produce solar cells from moon dust
To avoid expensive transportation, lunar colonists have to use existing materials – such as moon dust to produce solar cells.
This is how the team envisions the production of solar cells on the moon.
(Image: Sercan Ă–zen)
Transporting material into space is expensive. This is why space explorers are focusing on in situ resource utilization (ISRU), the use of existing resources. A team from Potsdam and Berlin has developed a solar cell that is made almost entirely from moon dust, the regolith.
The idea of the team led by Felix Lang from the University of Potsdam and Stefan Linke from the Technical University (TU) Berlin was to develop a solar cell that requires as little material as possible to be transported from Earth to the moon. The cell, which the researchers describe in the scientific journal Device, consists of only one percent terrestrial material.
The team uses the regolith to produce glass, which serves as a substrate for the solar cells. Only the perovskite, which forms the photoactive layer, would then have to be transported to the moon. This accounts for just one percent of the weight of the cell.
Regolith contains a lot of silicon dioxide
Regolith is a very fine dust that covers practically the entire surface of the moon. In the lunar highlands, just under half of the regolith consists of silicon dioxide – the raw material for glass – and just under a third of aluminum oxide. In addition, there is just under 15 percent calcium oxide and small amounts of iron and titanium oxide. The composition is different in the basalt-rich mares. Here, the proportion of metal oxides is higher at around 13 percent.
The team produced simulates of both regolith variants and used them to test the production of solar cells. The simulates were each heated to 1500 degrees Celsius to produce glass. On the moon, for example, a solar furnace could be used for this process.
(Image: Felix Lang)
The glass serves as a substrate onto which the perovskite, a separating layer of indium-doped tin oxide (ITO) and the electrode components are vapor-deposited. The top layer, in turn, is made of glass. Depending on the regolith composition, this is lighter or darker in color and therefore more or less permeable to sunlight.
Perovskite is well suited for lunar applications
According to the researchers, the semiconductor material perovskite is well suited for use on the moon: It can be extracted from a solution, is malleable and is particularly resistant to radiation, light and temperature fluctuations. "These solar cells only require 500 to 800 nanometer thin semiconductor layers, so one kilogram of perovskite raw material from Earth could be used to produce 400 square meters of solar cells on the moon," said Lang.
The regolith has been ground into an extremely fine dust over billions of years by meteorite impacts. It is electrostatic and therefore sticks to anything with a charge. It is very abrasive and damages everything it comes into contact with: spacesuits, vehicles, cameras, devices, but also people's airways and lungs. According to NASA, this makes lunar dust "one of the biggest challenges of living and working on the lunar surface". To get rid of the dust, the US space agency recently tested a system on the moon that uses electrodynamic forces to remove the dust from surfaces.
(wpl)