New Pathway Emerges To Improve Polycrystalline Thin-Film Solar Cell Performance
Puzzling out and testing new ways to improve the efficiency of cadmium telluride (CdTe) polycrystalline thin-film photovoltaic materials is a typical day in the life of National Renewable Energy Laboratory (NREL) research scientists Matthew Reese and Craig Perkins. Like any good puzzlers, they bring curiosity and keen observation to the task. These skills led them, over time, to make an intriguing observation. In fact, their discovery may prove to be a boon for the next generation of several different types of thin-film solar cells.
When fragments of solar cell material are crystallized together, or “grown” — think of a piece of rock candy growing in layers in a cup of sugar — they create a polycrystalline solar cell. With many layers come many surfaces, where one layer ends and another begins. These surfaces can cause defects that restrict the freedom of electrons to move, reducing the cell’s efficiency. As the cells are grown, researchers can introduce specific compounds that minimize the loss of electrons at these defects, in a process called “passivation.”
Reese, Perkins, and Colorado School of Mines doctoral student Deborah McGott noticed that the three-dimensional (3D) CdTe solar cells’ surfaces appeared to be covered in a very thin, two-dimensional (2D) layer that naturally eliminated surface defects. This 2D passivation layer forms in sheets on the 3D light-absorbing layer as the cell is growing, in a standard processing technique that is used around the globe. Despite the ubiquity of this 2D passivation layer, it had not been observed or reported in the research literature. Reese, Perkins, and McGott believed 2D passivation was also occurring naturally in other thin-film solar cells, like copper indium gallium selenide (CIGS) and perovskite solar cells (PSCs). They realized that this observation could lead to the development of new methods to improve the performance of many types of polycrystalline thin-film cells.
To confirm their hypothesis, they discussed it with NREL colleagues in the CdTe, CIGS, and PSC research groups. Through many informal discussions involving coffee, hallway chats, and impromptu meetings, Reese, Perkins, and McGott arrived at an “aha” moment. Their CdTe and CIGS colleagues confirmed that, while their research communities were not generally trying to perform 2D surface passivation in the 3D light-absorbing layer, it was, in fact, occurring. The PSC researchers said that they had noticed a 3D/2D passivation effect and were beginning to intentionally include compounds in device processing to improve performance. The “aha” moment took on even more significance.
“One of the unique things about NREL is that we have large groups of experts with different pools of knowledge working on CdTe, CIGS, and PSC technologies,” Reese said. “And we talk to each other! Confirming our hypothesis about naturally occurring 3D/2D passivation with our colleagues was easy because we share the successes and setbacks of our diverse research in an ongoing, informal, and collaborative way. We learn from each other. It is not something that typically happens in academic or for-profit-based polycrystalline thin-film solar cell research, where information is closely held, and researchers tend to remain siloed in their specific technology.”
The details of Reese, Perkins, and McGott’s discovery are presented in the article “3D/2D passivation as a secret to success for polycrystalline thin-film solar cells,” published in the journal Joule.
Supporting Evidence in the Literature
To confirm their findings, McGott conducted an extensive literature search and found considerable supporting evidence. The literature confirmed the presence of passivating 2D compounds in each of the CdTe, CIGS, and PSC technologies. No mention was made, however, of the 2D compounds’ ability to improve device performance in CdTe and CIGS technologies. While many articles on PSC technologies noted the naturally occurring 3D/2D passivation effect and discussed efforts to intentionally include specific compounds in device processing, none suggested that this effect might be active in other polycrystalline thin-film photovoltaic technologies.
Polycrystalline thin-film solar cells are made by depositing thin layers, or a thin film, of photovoltaic material on a backing of glass, plastic, or metal. Thin-film solar cells are inexpensive, and many people are familiar with their more unique applications. They can be mounted on curved surfaces — to power consumer goods, for example — or laminated on window glass to produce electricity while letting light through. The largest market for thin-film solar cell applications, however, is for CdTe thin film on rigid glass to make solar modules. CdTe modules are deployed at utility scale, where they compete directly with conventional silicon solar modules. Currently, commercial thin-film modules are generally less efficient than the best single crystal silicon solar modules, making performance improvements a high priority for polycrystalline thin-film researchers.
Key Properties of 2D Materials
Reese, Perkins, and McGott’s team used surface science techniques combined with crystal growth experiments to show that the 2D layers existed at and passivated 3D absorber surfaces in the three leading polycrystalline thin-film photovoltaic technologies. They then analyzed the key properties of successful 2D materials and developed a set of principles for selecting passivating compounds.
Finally, the team outlined key design strategies that will allow 3D/2D passivation to be employed in polycrystalline thin-film photovoltaic technologies more generally. This is particularly important because each 3D material requires a specific passivation approach.
The literature results, combined with lab-based observations, show that 3D/2D passivation may be the secret to success in enabling next-generation thin-film solar cells, particularly if researchers freely share the knowledge developed for each technology. The lack of 3D/2D passivation may even shed light on the stalled performance improvements of some polycrystalline technologies such gallium arsenide. By drawing parallels between the three technologies, Reese, Perkins, and McGott hope to demonstrate how the knowledge developed in each can — and should — be leveraged by other technologies, an approach that is seldom seen in polycrystalline thin-film solar cell research.
CdTe, CIGS, and PSC thin-film research at NREL is funded by the Department of Energy’s Solar Energy Technologies Office. Additional funding for Reese and McGott’s research is provided by the Department of Defense’s Office of Naval Research.
Learn more about photovoltaic research at NREL.
Article courtesy of the NREL, The U.S. Department of Energy.
Environment
Trump says India has ‘largely stopped’ buying Russian oil, hints at visiting the country next year
Tesla will continue to extend its “one-time” FSD transfer scheme for at least another quarter, according to CEO Elon Musk at today’s Tesla shareholder meeting.
Tesla’s shareholder meeting is underway, and the big headline is that shareholders have enthusiastically voted against their own interests, diluting their own voting rights and handing more control of the company to the one person on Earth currently negatively affecting its business the most, CEO Elon Musk.
At the end of the meeting, Tesla hosted a Q&A session with shareholders in attendance, and one of them asked a question we’ve heard before: whether Tesla owners who purchased Tesla’s Full Self-Driving software, which still has not been delivered despite the first purchases happening almost a decade ago at this point, would be able to transfer the licenses to that undelivered software if they choose to buy a new Tesla vehicle.
So far, Tesla’s official policy has been that owners must purchase FSD with each new vehicle they buy, and can’t transfer the licenses between them. However, it did offer a “one-time” exception to that rule for a two month period in 2023. After that, Tesla owners would never be allowed to transfer their FSD license again.
Well, except for the next time that Tesla allowed it. Then the next time. Then Tesla saying no, it won’t come back. Then it came back.
And now, it’s still active, having started in April.
So, the question was perhaps a little out of date. The program hasn’t just been active for a single quarter this time, but for the last half-year. There is no listed end date on Tesla’s website.
Nevertheless, Musk answered the question thusly:
We have done that a few times. I guess we could extend it again. Alright, we’ll extend it for at least another quarter, and then play it by ear after that.
This in fact seems like a limitation as compared to the current status of the program, since it is active with no end date at the moment. Musk mentioning that it might only last for another quarter suggests it may end earlier than Tesla’s website language currently suggests.
However, it’s been apparent all along that this is more of a way to stoke demand, hoping to get current owners to purchase FSD on new cars, so Tesla can hold on to the up to $15,000 it charged those owners for undelivered software.
Musk has continually stated, for more than a decade, that FSD is right around the corner. Consumers were led to believe that their FSD systems would be active soon, with Musk often stating it would be released by “next year.” Musk said that owners would be able to make money by running a robotaxi service, and that their cars would be “appreciating assets” because of it – and now Tesla is making revenue like that, but you can’t.
The years have come and went, and many cars are either out of service, getting old and reaching time for replacement, or owners have been scared away by Musk’s disgusting and high-profile political actions which have included sympathizing with Nazis.
Those owners who have moved on will seemingly never get back their investment into the false promises that Musk advanced, but it only makes sense that owners who do want to retain their license and move it to a new vehicle should be able to do so. Tesla sold software, the software still isn’t working, and people should be able to enjoy that software for a reasonable amount of time if they bought it.
And yet, Tesla continues jerking its most loyal owners around, those who have held strong through the incredible brand damage Musk is doing, and suggesting that the right thing to do is only available as a limited opportunity – trying to nickel and dime the most loyal owners into buying new cars earlier than they would have planned, with the specter of having to re-purchase FSD if they didn’t do so.
That said, there are several current cases in court covering the issue of Tesla’s false advertising regarding FSD. So this issue might be solved for the company by outside forces eventually anyway. But it would have been better if Tesla just did the right thing to begin with – which it continually resists doing.
The 30% federal solar tax credit is ending this year. If you’ve ever considered going solar, now’s the time to act. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. It has hundreds of pre-vetted solar installers competing for your business, ensuring you get high-quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use, and you won’t get sales calls until you select an installer and share your phone number with them.
Your personalized solar quotes are easy to compare online and you’ll get access to unbiased Energy Advisors to help you every step of the way. Get started here.
FTC: We use income earning auto affiliate links. More.
Tesla CEO Elon Musk pushed back the dates for a demo of the next-gen Tesla Roadster, which he has said will be able to “fly” and suggested that it might not even be a car at all.
Tesla has been teasing the existence of a future, high-performance sportscar model for years now. Originally it was unveiled in 2017 for a 2020 release, but has been repeatedly pushed back, with another delay today.
Just last week, Musk said that a demo was coming at the end of the year of the Roadster, and that it would be perhaps the most exciting demo of any product ever. Musk also stated that the Roadster will have more tech than all James Bond vehicles combined
Today, he was asked a question at Tesla’s shareholder meeting about the status of that project (including whether the “James Bond” tech would make it to other Teslas – to which Musk responded “um, no”). Here’s the full answer regarding the product’s unveiling:
The product unveil of the Roadster 2, which will be very different than what we’ve shown previously, that demo event will be April 1 of next year. I have some deniability because I can say I was just kidding. But we are actually tentatively aiming for April 1, for what I think will be the most exciting, whether it works or not, demo of any product. And then I guess production is probably about 12-18 months after that. I think production is about a year or so after that.
When the questioner seemed to respond with disbelief with that answer (who ever thought that this car could ever possibly be delayed?!), Musk answered:
Well, I can’t give away secrets, but you won’t be disappointed.
Musk also said, during the meeting, that owners of Founders’ Series reservations, which represent a $250,000 loan given to Tesla for the last 8 years, would all be invited to the demo.
This new timeline represents yet another delay for the oft–delayed vehicle. The most recent official announcement suggested it would go into production this year, though Musk has waffled on that.
So, this official announcement puts us back to a timeline of April 1 for the reveal, which is a delay of at least 3 months from when it was supposed to occur as of last week, and production starting (not cars hitting the road) at least in April 2027, or at late as potentially October 2027. If we take the higher end of that range, then the Roadster is likely to only be available in 2028, 11 years after its first unveiling and 8 years after original estimates.
That said, it’s not much of a surprise that the Roadster would be delayed again. Just last week, we saw a new job listing for the Roadster, looking for a “concept development” engineer. That’s a fairly early part of the production process, and even makes it seem like a 2027 release could be optimistic.
In the interim, several other high-performance electric cars have appeared to give the “hard-core smack down” to gas-powered cars that Musk promised.
We’ve seen records set by the Xiaomi SU7 Ultra, built by a smartphone company from concept to production in just a couple years. We’ve seen the Rimac Nevera R get to 186mph faster than a Bugatti Chiron Super Sport. We’ve seen the Lotus Evija X, which set the third-fastest Nurburgring lap ever, only beaten by two one-off, track-only, purpose-built racecars (one of which is a hybrid, the other is electric). And we’ve seen the BYD Yangwang U9 Xtreme become the fastest production car ever at 308(!!!) miles per hour.
These are milestones that the Roadster might have been able to take a shot at, but time has passed it by, and others have stepped in in the Roadster’s absence.
But maybe that doesn’t matter, because Musk’s comments today suggest the Roadster might not be what we expected.
All along, it has been assumed that the Roadster will be something like the original version unveiled in 2017. But today, Musk said it will be “very different than what we’ve shown previously.” We don’t know what those differences entail – whether it just means the car will have new tech, or if it will be a completely different style of car.
We can imagine that anyone who gave Tesla a $250,000 loan for ten years might be bothered by ending up with a totally different bill of goods than they put their money down for, though, so we hope the plan is to at least keep it a sportscar.
There are some questions about whether these technologies Musk has mentioned will be on the car, though, and if they will be helpful for anything other than a demo if so.
Recently, Tesla patented a “fan car” system which would enhance grip. It’s actually a pretty cool patent, with interesting improvements over previous implementations of the same idea.
But it is decidedly not a “flying car.” In fact, being able to fly would not actually help sportscar performance, and would actually hurt it. Sportscars are typically looking to maximize downforce in the most efficient manner, in order to enhance grip, but to fly, one must create “upforce,” which isn’t a term anyone uses because it creates no actual performance benefit.
So, while it is highly expected that the Roadster demo might be able to “fly,” we hope that doesn’t make it to production on a sportscar, as that’s more of a parlor trick and would take performance benefits away from where they would be more useful – like having a fan car system, or directional jets to increase lateral acceleration, rather than useless upwards acceleration.
The 30% federal solar tax credit is ending this year. If you’ve ever considered going solar, now’s the time to act. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. It has hundreds of pre-vetted solar installers competing for your business, ensuring you get high-quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use, and you won’t get sales calls until you select an installer and share your phone number with them.
Your personalized solar quotes are easy to compare online and you’ll get access to unbiased Energy Advisors to help you every step of the way. Get started here.
FTC: We use income earning auto affiliate links. More.
-
Sports2 years agoStory injured on diving stop, exits Red Sox game
-
Sports3 years ago‘Storybook stuff’: Inside the night Bryce Harper sent the Phillies to the World Series
-
Sports2 years agoGame 1 of WS least-watched in recorded history
-
Sports3 years agoButton battles heat exhaustion in NASCAR debut
-
Sports3 years agoMLB Rank 2023: Ranking baseball’s top 100 players
-
Sports4 years ago
Team Europe easily wins 4th straight Laver Cup
-
Environment2 years agoJapan and South Korea have a lot at stake in a free and open South China Sea
-
Environment1 year agoHere are the best electric bikes you can buy at every price level in October 2024