The conquest of space is currently the most important goal of modern science and technology. Powering space missions requires advanced, reliable energy sources that can withstand extreme conditions beyond Earth. In a space industry dominated by solar cells, where gallium arsenide plays a major role, researchers from the University of Michigan are testing organic solar cells. We needed something like this.
In search of the perfect one
Gallium arsenide solar cells, the most commonly used in space today, are famous for their high efficiency and resistance to radiation damage. However, they have many disadvantages: they are expensive, heavy and inflexible. In turn, traditional silicon cells do not cope well with protons emitted from the Sun. Organic solar cells offer an alternative: they are light, flexible and potentially cheaper to produce. In a recent study, a team of scientists from the University of Michigan conducted radiation testswhich showed that organic materials can outperform traditional ones in terms of performance in space.
How do organic solar cells work?
Organic cells use organic molecules to convert light into electricity. Research indicates that not all types of organic materials behave the same in space conditions. The small molecule cells survived three years of radiation exposure without noticeable damage. However, polymer cells lost as much as 50% of efficiency due to the splitting of side chains of molecules. The damage created electron traps, impeding their flow. Interestingly, these “traps” can be repaired by thermal annealing. Exposing the cells to temperatures of around 100°C allows the hydrogen to re-bond to the carbon, eliminating electron traps.
The thing about searching for perfect solutions is that they are usually not perfect – unfortunately. Their advantages include lightness and flexibility, which makes them ideal for applications where literally every gram matters, e.g. in space missions. Moreover, the heat generated by the Sun may allow the cells to regenerate during the mission; it is worth noting the potentially lower production cost, as organic materials are cheaper than gallium arsenide. However, the disadvantages of organic cells include lower stability, especially in the case of polymers, and limitations in long-term reliability, as it is not known whether self-healing will be effective in very long missions in space.
Researchers are considering next steps
Researchers from the University of Michigan suggest two directions of development. The first is to design materials that do not generate electron traps. The second is to improve self-repair methods, e.g. by filling traps with atoms of other elements. The team has even already filed a patent application for this technology. Subsequent research will aim to improve the durability and reliability parameters of organic cells in extreme conditions.
Organic solar cells are not yet ready for mass use in space, but it is still a breakthrough. As research progresses, we can expect a solution that will help us a bit in space exploration. And this will be the sphere that will determine our further progress.
Source: antyweb.pl
