Atom swapping could lead to ultra-bright, flexible next generation LEDs

sc604 — Mon, 07 Jun 2021 15:25:23 +0000

̽��ֱ��researchers, led by the ̽��ֱ�� of Cambridge and the Technical ̽��ֱ�� of Munich, found that by swapping one out of every 1,000 atoms of one material for another, they were able to triple the luminescence of a new material class of light emitters known as halide perovskites.

This ‘atom swapping’, or doping, causes the charge carriers to get stuck in a specific part of the material’s crystal structure, where they recombine and emit light. ̽��ֱ��results, reported in the Journal of the American Chemical Society, could be useful for low-cost printable and flexible LED lighting, displays for smartphones or cheap lasers.

Many everyday applications now use light-emitting devices (LEDs), such as domestic and commercial lighting, TV screens, smartphones and laptops. ̽��ֱ��main advantage of LEDs is they consume far less energy than older technologies.

Ultimately, also the entirety of our worldwide communication via the internet is driven by optical signals from very bright light sources that within optical fibres carry information at the speed of light across the globe.

̽��ֱ��team studied a new class of semiconductors called halide perovskites in the form of nanocrystals which measure only about a ten-thousandth of the thickness of a human hair. These ‘quantum dots’ are highly luminescent materials: the first high-brilliance QLED TVs incorporating quantum dots recently came onto the market.

̽��ֱ��Cambridge researchers, working with Daniel Congreve’s group at Harvard, who are experts in the fabrication of quantum dots, have now greatly improved the light emission from these nanocrystals. They substituted one out of every one thousand atoms with another – swapping lead for manganese ions – and found the luminescence of the quantum dots tripled.

A detailed investigation using laser spectroscopy revealed the origin of this observation. “We found that the charges collect together in the regions of the crystals that we doped,” said Sascha Feldmann from Cambridge’s Cavendish Laboratory, the study’s first author. “Once localised, those energetic charges can meet each other and recombine to emit light in a very efficient manner.”

“We hope this fascinating discovery: that even smallest changes to the chemical composition can greatly enhance the material properties, will pave the way to cheap and ultrabright LED displays and lasers in the near future,” said senior author Felix Deschler, who is jointly affiliated at the Cavendish and the Walter Schottky Institute at the Technical ̽��ֱ�� of Munich.

In the future, the researchers hope to identify even more efficient dopants which will help make these advanced light technologies accessible to every part of the world.

Reference:
Sascha Feldmann et al. ‘Charge carrier localization in doped perovskite nanocrystals enhances radiative recombination.’, Journal of the American Chemical Society (2021). DOI: 10.1021/jacs.1c01567

An international group of researchers has developed a new technique that could be used to make more efficient low-cost light-emitting materials that are flexible and can be printed using ink-jet techniques.

Ella Maru Studio

Artist’s impression of glowing halide perovskite nanocrystals

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Green tech startups see boost in patents and investment when partnering with government – study

fpjl2 — Mon, 18 Mar 2019 10:02:11 +0000

Latest research on hundreds of new green technology companies in the US shows the patenting activity of a startup climbs by over 73% on average every time they collaborate with a government agency on “cleantech” development – from next-generation solar cells to new energy storage materials.

̽��ֱ��study also found that every time a cleantech startup licensed a technology developed by a government agency, the company secured – on average – more than double the amount of financing deals when compared to similar startups: a 155% increase one year after taking out a licence.

Collaboration with universities and private firms are a familiar path for many startups, yet government partnerships are significantly undervalued when it comes to green technologies, say researchers.

While the role of public-private partnerships in sectors such as biotech and IT is well known, they say that – until now – there has been a lack of data on the effectiveness of these alliances in cleantech. ̽��ֱ��study is published in the journal Research Policy.

“Our findings suggest that some of the signs commonly used to track innovation and business success, such as patents and financing, increase when new cleantech companies partner with US government departments or labs,” said study co-author Laura Diaz Anadon, Professor of Climate Change Policy at the ̽��ֱ�� of Cambridge.

Prof Claudia Doblinger, study first author from the Technical ̽��ֱ�� of Munich, said: “Government research laboratories have a major role to play in the climate challenge but also the growth of small businesses – twin objectives at the heart of many policy discussions, such as the Green New Deal in the United States.”

̽��ֱ��researchers built a new dataset of 657 US cleantech startups and the more than 2,000 partnerships those companies established between 2008 and 2012, to gauge the different outcomes for private and public alliances.

Around 66% of the startups were less than five years old in 2008, with the remaining 34% commencing during the selected study period. ̽��ֱ��research included companies across the sustainable sector: from wind to marine power, and recycling to batteries.

In addition to the benefits seen in patenting and investment, researchers also found that alliances with some of the stronger innovation outcomes were outside of major tech hubs such as Silicon Valley – suggesting the potential for building “regional ecosystems”.

̽��ֱ��National Renewable Energy Laboratory (NREL), for example, part of the US Department of Energy and situated in Colorado, is a “prominent example of government organisations in the US partnering with cleantech startups”, say researchers.

A major player in the development of green technologies, NREL it worked throughout the 2000s with startup companies in “thin film” such as First Solar, which in 2009 became the largest producer of Cadmium Telluride solar technology.

Researchers point out that NREL has granted more than 260 licenses since 2000, and this study shows the value of government agencies such as this have on startups in particular.

̽��ֱ��study’s authors argue that the scale, facilities, and longer-term perspective of state agencies, such as the US Department of Energy and its seventeen national laboratories, naturally complement the nimble startups that can sniff out and adapt technological developments to market opportunities at a faster rate.

“Governments can and should have longer-term perspectives when compared to the private sector, and thus play a critical role in energy innovation,” said study co-author Prof Kavita Surana, from the ̽��ֱ�� of Maryland.

“Beyond grants and supporting the early markets, it is the joint development and transfer of knowledge that government agencies are able to foster with startups that makes a difference.

“As the US Congress and civil society prepare to debate the substance of the policies like the Green New Deal, facilitating public-private partnerships could well be an important, and relatively inexpensive, part of any forward-looking policy package,” said Surana.

Doblinger says that to forge lasting partnerships with emerging businesses, government agencies should test out incentives that support collaborative projects.

“Initiatives such as investing more in technology transfer capabilities, starting entrepreneurs in residence programs, or allowing government scientists to take temporary leave to work with a private firm, could reduce information asymmetry and provide incentives to researchers,” she said.

Anadon believes that the lessons from the study are worth considering in national contexts beyond the US. “For the agencies of any government to successfully work with startups, sufficient and stable funding is vital – along with technology transfer and communication support.”

“Our findings should be taken into consideration whenever funding for public research into sustainable energy is being debated. Cleantech that comes from public-private partnerships will be essential for meeting global climate and sustainability goals,” she said.

A bold response to the world’s greatest challenge
̽��ֱ�� ̽��ֱ�� of Cambridge is building on its existing research and launching an ambitious new environment and climate change initiative. Cambridge Zero is not just about developing greener technologies. It will harness the full power of the ̽��ֱ��’s research and policy expertise, developing solutions that work for our lives, our society and our biosphere.

Collaboration between government and startups could help meet the climate challenge while growing small businesses. Findings could inform discussions on Green New Deal or any “forward-looking policy package” say researchers.

Cleantech that comes from public-private partnerships will be essential for meeting global climate and sustainability goals

Laura Diaz Anadon

NREL

Photovoltaic array at the National Wind Technology Center near Boulder, Colorado

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̽��ֱ�� of Cambridge - Technical ̽��ֱ�� of Munich

Atom swapping could lead to ultra-bright, flexible next generation LEDs

Green tech startups see boost in patents and investment when partnering with government – study