The Intertubes have been lighting up like fire ever since word dropped that the results are in for the first ever space flight of perovskite solar cells. Despite their razor-thin profile and delicate solution-based construction, the new solar cells returned to Earth intact while sending back all the juicy details about their performance in the up-above. Spoiler alert: on a gram-per-gram basis, perovskite comes out miles ahead of the competition.
Perovskite Solar Cells In Outer Space!
For those of you new to the topic, solar cells have been used in space operations since 1959, and space applications paved the way for the affordable, down-to-Earth versions that millions of electricity users enjoy today, mainly in the form of low cost silicon technology.
The perovskite version is a relatively new development, with research picking up mainly after 2006. Perovskite is much lighter than silicon, less expensive than other solar materials, and easier to convert into a functioning PV device, which means that the next generation of solar cells could be even more affordable than ever.
Perovskite solar cells are also lightweight and flexible. That provides them with opportunities for application on clothing, buildings, cars, and, of course, rockets, among other things.
All things being equal, the space-friendly performance of perovskite cells indicates that the new PV technology could find widespread application here on Earth, once all the kinks are worked out.
One of those kinks is durability. Early iterations of perovskite PV cells dissolved under ambient conditions. The space flight demonstrates how far the R&D has progressed since then.
Gram-For-Gram, Perovskite Solar Cells Put Out
Another one of those kinks is solar conversion efficiency. The latest perovskite solar cells are still less efficient than their silicon counterparts, but they have come a long way from the measly single-digit performance of early attempts.
As of 2020, new perovskite technology clocks in at an impressive 25% or more. Combined with low cost and other attributes, that puts perovskite in the running to compete in the commercial marketplace.
And, that could include the increasingly commercial environment of outer space.
Last year, a team of researchers from the Technical University of Munich partnered with the German Aerospace Center to send two batches of hybrid perovskite and organic solar cells 240 kilometers up into space. The results were just published last week in the journal Joule, and they are pretty spectacular.
You can get all the details from the study under the title, “Perovskite and Organic Solar Cells on a Rocket Flight.”
For those of you on the go, the key point is that the solar cells exceeded power densities between 7 and 14 mW cm−2 , which means that they outperformed the competition by a mile.
Stated another way, conventional solar cells used in space achieve about three watts per gram. The TUM team is looking at up to 30 watts per gram.
In another important finding, the TUM team reported that the solar cells continued to produce electricity when turned away from the sun, by soaking up light reflected from the Earth.
That’s an important finding, considering that Earthlings are beginning to take a serious look at traveling to Mars, and beyond into deep space.
TUM team, for one, is already anticipating such a journey.
“Due to their much thinner thickness, the new solar cells could therefore also be used in much dimmer light, for example on missions to the outer solar system on which the sun is too weak for conventional space solar cells,” TUM enthused in a press release.
That thing about thinner thickness also provides advantages for engineering fold-able and flexible devices for space exploration.
“…their key advantage qualifying them as space solar cells is wet-chemical processability at ambient temperatures,” the research team writes. “In contrast to conventional inorganic solar cells, this allows the deposition (via spin coating, printing, spraying, to name a few) of the (sub-)μm thick cells onto ultra-thin and light-weight polymer foils as flexible and foldable substrates.”
The Solar Power Revolution Has Only Just Begun
Meanwhile back on Earth, the US Department of Energy has been a longtime fan of perovskite solar cell technology. In an epic case of perfect timing, last Thursday the agency announced a new round of $20 million in funding for perovskite research, which digs intensively into the field testing issues explored by the TUM team, only Earthbound instead of out there in space.
No, the Energy Department’s big news has not distracted the public eye from the latest news about the *Trump administration, in which various officials face the possibility of serious criminal charges for disrupting the mail (spoiler alert: presidential pardons do not apply to state charges).
However, all of that aside, the new funding round is still big news. It is aimed straight restoring the nation’s PV industry to the global dominance it once enjoyed in the 20th century.
“We will continue to invest in early-stage research and development to improve the affordability, reliability, and value of solar technologies on the grid and position the United States as the world’s leading manufacturer of clean energy technologies,” said Energy Secretary Dan Brouillette, perhaps forgetting that his boss promised to save coal jobs, not create new PV jobs.
In this round of funding, the Energy Department is seeking foundational research projects that boost both efficiency and stability beyond current state-of-the-art levels.
The agency is also seeking experienced business partners, both for-profit and nonprofit, to lend a hand with scaling up manufacturing processes.
Perhaps the most important item is the one in which the Energy Department aims to create a gold standard for technology validation.
“Independence and neutrality are required to ensure there are no conflicts of interest between this effort and other projects seeking to demonstrate high-performance devices,” they emphasize. “This center will be responsible for developing and refining test protocols, including accelerated life testing that closely correlates with long-term field performance.”
They are not kidding around about that field testing.
“The center will also be responsible for operating an extensive field testing effort using devices produced by the R&D community to iteratively refine all test protocols and improve community understanding of remaining stability and performance issues,” they continue.
The effort also includes a close look at lifecycle environmental impacts, which is an important consideration in the perovskite solar cell field.
As momentum builds for a green COVID-19 recovery, it sure looks like the Energy Department is determined not to be left behind. Although the agency was recently excoriated for proposing a rollback of water efficiency standards, the new perovskite funding was just one item in a flurry of news pushed out the Energy Department last week, the new ARIES research platform being one of them.
ARIES will enable its host, the National Renewable Energy Laboratory, to scale clean tech experiments up to the 20-megawatt level for grid-level applications.
That includes electric vehicles, renewable generation, hydrogen, energy storage, and grid-interactive efficient buildings according to the Energy Department, so it looks like the new round of perovskite funding will dovetail with the effort.
What was that about coal jobs again?
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Photo (cropped): “Start of the ATEK / MAPHEUS-8 rocket in the early morning from Kiruna (Sweden), prepared and carried out by the Mobile Missile Base (MORABA) department of DLR.” Credit: DLR (CC-BY 3.0) via Eurekalert.