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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 CdTeCIGS, 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.


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Sam Bankman-Fried FTX fraud victim tells judge: ‘My whole life has been destroyed’

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Sam Bankman-Fried FTX fraud victim tells judge: 'My whole life has been destroyed'

NEW YORK, US – JANUARY 03: Sam Bankman-Fried leaves the court in New York, on January 03, 2023. 

Fatih Aktas | Anadolu Agency | Getty Images

In a letter to the Department of Justice, an FTX customer who lost $4 million when the exchange filed for bankruptcy in 2022 expressed disgust at a circulating narrative that clients of the crypto exchange would ever be made whole.

“I have scraped the docket of scheduled claims and calculated the exact amount stolen,” wrote the former FTX customer, whose identity has been concealed by the government. “The total value of customer liabilities is $19,722,911,002.84.”

This week, that letter ended up on the desk of U.S. District Judge Lewis Kaplan, who on Thursday will inform FTX founder Sam Bankman-Fried of his prison sentence stemming from his role in the collapse of the exchange. At 9:30 a.m., sentencing proceedings will take place on the 26th floor of the federal courthouse in downtown Manhattan, the same place where a jury found the former crypto executive guilty of all seven criminal counts against him in November.

The victim, who wrote that 30 years worth of savings had been deposited into FTX three months before the exchange collapsed, is part of a last-minute push by prosecutors to sway Judge Kaplan ahead of the sentencing.

“My whole life has been destroyed,” the person wrote. “I have 2 young children, one born right before the collapse. Beyond the money, I lost my happiness, my ability to get out of bed, my desire to continue living. My wife is suicidal and depressed.”

The same sorts of stories were told during Bankman-Fried’s monthlong criminal trial last year. Prosecutors won their case by convincing jurors that Bankman-Fried had stolen at least $8 billion from customers. For some people, that meant financial ruin.

“In its sentencing submission, the prosecution has included moving accounts from FTX’s former customers that speak to the devastation experienced by those losing their money, the uncertainty of wondering whether they might ever get any of it back, and dealing with the emotional fallout of being duped,” said Yesha Yadav, law professor and Associate Dean at Vanderbilt University. “These victim impact statements can be very powerful.”

Sam Bankman-Fried faces up to 50 years in prison at sentencing hearing

Bankman-Fried, 32, faces a maximum sentence of more than 100 years in prison, though the government has suggested a sentence in the range of 40 to 50 years. The defense is angling for no more than 6.5 years.

For months, Judge Kaplan has been weighing the appropriate punishment for Bankman-Fried’s crimes related to the implosion of his $32 billion crypto empire.

CNBC spoke to former federal prosecutors, trial attorneys, and a mix of lawyers working to defend white collar criminals to get their take on what to expect on Thursday.

Damaging testimony

Bankman-Fried was convicted of wire fraud and conspiracy to commit wire fraud against FTX customers and against lenders to sister hedge fund Alameda Research, as well as conspiracy to commit securities fraud and conspiracy to commit commodities fraud against FTX investors, and conspiracy to commit money laundering.

The defense team has argued that Bankman-Fried’s sentence should reflect the potential that FTX customers will be paid back in part or in full. The likelihood of that scenario has increased in recent months thanks to the rising value of cryptocurrencies and other assets FTX owned, such as its stake in artificial intelligence startup Anthropic.

Even as the bankruptcy estate promises to pay customers back, many of FTX’s thousands of victims argue that their crypto stakes have been significantly undervalued by the exchange’s new leadership team.

“A lot will be said about the loss at the time of the conduct, not the recovery or potential recovery after it was discovered,” said former federal and state prosecutor David Weinstein, who now practices as a corporate compliance and white collar defense attorney at Jones Walker. Weinstein said he expects to see a sentence in the range of 30 to 40 years.

Mark Bini, a former state and federal prosecutor and U.S. assistant attorney who specialized in financial crimes, anticipates a sentence of no less than 30 years. 

“Probation calculates the guidelines at 110 years,” said Bini, who currently represents white collar crypto defendants as part of law firm Reed Smith’s On Chain digital asset team. “I think the judge is likely to side with probation and the government on the loss amount and the appropriate guidelines.”

Caroline Ellison, former chief executive officer of Alameda Research LLC, arrives to court in New York, US, on Thursday, Oct. 12, 2023.

Bloomberg | Bloomberg | Getty Images

Judge Kaplan, 78, is a veteran of the Southern District of New York and has presided over some of the biggest cases to roll through his courthouse. He showed little patience for Bankman-Fried during the defendant’s four days on the stand.

“Unfortunately for SBF, some of his testimony at trial came across as highly evasive, somewhat cold and often contradictory,” said Yadav, adding that a sentence of 20 to 25 years could offer Judge Kaplan a way to balance the severity of the crime with a recognition of customer recoveries and the potential for future rehabilitation.

Former federal prosecutor Neama Rahmani described Kaplan as “old school” and predicted a sentence of 20 to 30 years.

Tre Lovell, a Los Angeles corporate law attorney, said the core factors Kaplan will consider will be the extent of the fraud, along with the fact that Bankman-Fried appeared to have lied under oath while showing little remorse.

“The judge isn’t going to cut Bankman-Fried a break just because FTX has recovered a lot of funds to offset the amount that customers lost,” Lovell said. “The judge is just going to look at Bankman-Fried’s conduct at the time he was in charge of the company, not what the company did after he stepped down as CEO.”

Bankman-Fried has one last chance to take the stand in front of the judge in order to show some level of contrition and a promise to become a benefit to society.

“If he says he’s had a chance to think about what he did and that he’s very sorry for misusing the hard-won funds of investors, and that he wants to use his acumen in this field for the public good, then he may walk out with a prison sentence that is south of 20 years,” Lovell said. “In court, it’s never too late to say you’re sorry. But he won’t get a big discount on his sentence just for being contrite.”

WATCH: Prosecutors recommend a 40-50 year prison sentence for Bankman-Fried

Prosecutors recommend a prison sentence of 40-50 years for Sam Bankman-Fried in FTX fraud

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HD Hyundai announces lithium phosphate battery pack for commercial trucks

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HD Hyundai announces lithium phosphate battery pack for commercial trucks

HD Hyundai Infracore (HDI) is set to debut a new, 35 kWh lithium phosphate battery pack to power the next generation of electrified commercial equipment.

While the new HD Hyundai lithium phosphate battery isn’t technically out yet (it will officially bow at Intermat 2024 at Paris-Nord Villepinte next month), the battery pack has been in development since back when Infracore was still a Doosan brand.

As of 2021, the first prototypes of the battery were configured with bespoke battery management system (BMS) and thermal protection systems, as well as a flexible design architecture that allows the manufacturer to produce batteries with different voltages and capacities by using different numbers of standardized cylindrical nickel cobalt manganese (NCM) battery cells (that’s actually an NCM pack shown, at top).

The OG Doosan

Battery pack prototype no. 1, developed in-house by (then) Doosan Infracore; via HD Hyundai.

Different versions of the Infracore battery have been in used in the company’s 1.7 ton mini electric excavators since 2023. And they’re not alone. HD Hyundai currently offers LFP battery packs in 5.8, 8.8 and 11.7 kWh power capacities – but these news ones that are set to bow are expected to be much bigger.

Like, “big enough to power a commercial truck,” bigger.

Coming to an electric truck near you

Tata Daewoo’s C-segment truck which feature the new Infracore LFP battery pack; via HD Hyundai.

HDI recently confirmed that it will supply battery packs for Tata Daewoo Commercial Vehicle’s medium-duty electric trucks, and announced that the two companies will work together to expand Korea’s electric commercial offerings.

The official HDI release cites data from market research platform, Markets and Markets, that projects the global electric commercial vehicle market to grow from the 529,400 units sold in 2023 to more than 2.1 million units by 2030.

“We have been able to pioneer the EV market with on our proprietarily produced battery pack technology,” says HD Hyundai Infracore CEO, Seung-hyun Oh, “Based on such success, we plan to gradually expand the vehicle types applied with our battery packs and extend our supplier base to emerging countries and other regions.”

The new battery packs are intended to, “offer a value-oriented and robust solution for companies operating in the construction, industrial and marine sectors,” according to Power Progress (formerly Diesel Progress). We’ll have more when Hyundai lifts the veil in Paris.

Electrek’s Take

Hyundai Concept X at CES2024
Image by the author.

If their sprawling, interactive display at CES didn’t already convince you, Hyundai is serious about electrifying job sites around the world. Yes, they’re also working on hydrogen – but their concerted push to become global EV leaders is very real.

Construction companies like Caterpillar and Deere should would do well to learn the lesson Toyota and Honda learned the hard way in the 90s: underestimate the Koreans at your peril.

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Daily EV Recap: An autonomous EV that can drift

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Listen to a recap of the top stories of the day from Electrek. Quick Charge is now available on Apple PodcastsSpotifyTuneIn and our RSS feed for Overcast and other podcast players.

New episodes of Quick Charge are recorded Monday through Thursday and again on Saturday. Subscribe to our podcast in Apple Podcast or your favorite podcast player to guarantee new episodes are delivered as soon as they’re available.

Stories we discuss in this episode (with links):

Tesla wants to bring ‘private 5G’ to its EVs and Optimus robot

Volvo makes its last diesel car and puts it in a museum

Elon Musk says Tesla Optimus robot should cost ‘less than half of a car’

Hyundai reveals ambitious $50 billion investment to secure a top 3 spot in the EV market

Ghost ride the whip! Geely shows off AI chassis performing fully-autonomous drifting 

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