̽��ֱ�� of Cambridge - European Union

Spinning, twisted light could power next-generation electronics

sc604 — Thu, 13 Mar 2025 18:09:28 +0000

̽��ֱ��researchers, led by the ̽��ֱ�� of Cambridge and the Eindhoven ̽��ֱ�� of Technology, have created an organic semiconductor that forces electrons to move in a spiral pattern, which could improve the efficiency of OLED displays in television and smartphone screens, or power next-generation computing technologies such as spintronics and quantum computing.

̽��ֱ��semiconductor they developed emits circularly polarised light—meaning the light carries information about the ‘handedness’ of electrons. ̽��ֱ��internal structure of most inorganic semiconductors, like silicon, is symmetrical, meaning electrons move through them without any preferred direction.

However, in nature, molecules often have a chiral (left- or right-handed) structure: like human hands, chiral molecules are mirror images of one another. Chirality plays an important role in biological processes like DNA formation, but it is a difficult phenomenon to harness and control in electronics.

But by using molecular design tricks inspired by nature, the researchers created a chiral semiconductor by nudging stacks of semiconducting molecules to form ordered right-handed or left-handed spiral columns. Their results are reported in the journal Science.

One promising application for chiral semiconductors is in display technology. Current displays often waste a significant amount of energy due to the way screens filter light. ̽��ֱ��chiral semiconductor developed by the researchers naturally emits light in a way that could reduce these losses, making screens brighter and more energy-efficient.

“When I started working with organic semiconductors, many people doubted their potential, but now they dominate display technology,” said Professor Sir Richard Friend from Cambridge’s Cavendish Laboratory, who co-led the research. “Unlike rigid inorganic semiconductors, molecular materials offer incredible flexibility—allowing us to design entirely new structures, like chiral LEDs. It’s like working with a Lego set with every kind of shape you can imagine, rather than just rectangular bricks.”

̽��ֱ��semiconductor is based on a material called triazatruxene (TAT) that self-assembles into a helical stack, allowing electrons to spiral along its structure, like the thread of a screw.

“When excited by blue or ultraviolet light, self-assembled TAT emits bright green light with strong circular polarisation—an effect that has been difficult to achieve in semiconductors until now,” said co-first author Marco Preuss, from the Eindhoven ̽��ֱ�� of Technology. “ ̽��ֱ��structure of TAT allows electrons to move efficiently while affecting how light is emitted.”

By modifying OLED fabrication techniques, the researchers successfully incorporated TAT into working circularly polarised OLEDs (CP-OLEDs). These devices showed record-breaking efficiency, brightness, and polarisation levels, making them the best of their kind.

“We’ve essentially reworked the standard recipe for making OLEDs like we have in our smartphones, allowing us to trap a chiral structure within a stable, non-crystallising matrix,” said co-first author Rituparno Chowdhury, from Cambridge’s Cavendish Laboratory. “This provides a practical way to create circularly polarised LEDs, something that has long eluded the field.”

̽��ֱ��work is part of a decades-long collaboration between Friend’s research group and the group of Professor Bert Meijer from the Eindhoven ̽��ֱ�� of Technology. “This is a real breakthrough in making a chiral semiconductor,” said Meijer. “By carefully designing the molecular structure, we’ve coupled the chirality of the structure to the motion of the electrons and that’s never been done at this level before.”

̽��ֱ��chiral semiconductors represent a step forward in the world of organic semiconductors, which now support an industry worth over $60 billion (about £45 billion). Beyond displays, this development also has implications for quantum computing and spintronics—a field of research that uses the spin, or inherent angular momentum, of electrons to store and process information, potentially leading to faster and more secure computing systems.

̽��ֱ��research was supported in part by the European Union’s Marie Curie Training Network and the European Research Council. Richard Friend is a Fellow of St John’s College, Cambridge. Rituparno Chowdhury is a member of Fitzwilliam College, Cambridge.

Reference

Rituparno Chowdhury, Marco D Preuss et al. ‘Circularly polarized electroluminescence from chiral supramolecular semiconductor thin films.’ Science (2025). DOI:10.1126/science.adt3011

Researchers have advanced a decades-old challenge in the field of organic semiconductors, opening new possibilities for the future of electronics.

It’s like working with a Lego set with every kind of shape you can imagine, rather than just rectangular bricks

Richard Friend

Samarpita Sen, Rituparno Chowdhury

Confocal microscopy image of a chiral semiconductor

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Scientists develop ‘smart pyjamas’ to monitor sleep disorders

sc604 — Tue, 18 Feb 2025 11:06:44 +0000

̽��ֱ��team, led by the ̽��ֱ�� of Cambridge, developed printed fabric sensors that can monitor breathing by detecting tiny movements in the skin, even when the pyjamas are worn loosely around the neck and chest.

̽��ֱ��sensors embedded in the smart pyjamas were trained using a ‘lightweight’ AI algorithm and can identify six different sleep states with 98.6% accuracy, while ignoring regular sleep movements such as tossing and turning. ̽��ֱ��energy-efficient sensors only require a handful of examples of sleep patterns to successfully identify the difference between regular and disordered sleep.

̽��ֱ��researchers say that their smart pyjamas could be useful for the millions of people in the UK who struggle with disordered sleep to monitor their sleep, and how it might be affected by lifestyle changes. ̽��ֱ��results are reported in the Proceedings of the National Academy of Sciences (PNAS).

Sleep is vital for human health, yet more than 60% of adults experience poor sleep quality, leading to the loss of between 44 and 54 annual working days, and an estimated one percent reduction in global GDP. Sleep behaviours such as mouth breathing, sleep apnoea and snoring are major contributors to poor sleep quality, and can lead to chronic conditions such as cardiovascular disease, diabetes and depression.

“Poor sleep has huge effects on our physical and mental health, which is why proper sleep monitoring is vital,” said Professor Luigi Occhipinti from the Cambridge Graphene Centre, who led the research. “However, the current gold standard for sleep monitoring, polysomnography or PSG, is expensive, complicated and isn’t suitable for long-term use at home.”

Home devices that are simpler than PSG, such as home sleep tests, typically focus on a single condition and are bulky or uncomfortable. Wearable devices such as smartwatches, while more comfortable to wear, can only infer sleep quality, and are not effective for accurately monitoring disordered sleep.

“We need something that is comfortable and easy to use every night, but is accurate enough to provide meaningful information about sleep quality,” said Occhipinti.

To develop the smart pyjamas, Occhipinti and his colleagues built on their earlier work on a smart choker for people with speech impairments. ̽��ֱ��team re-designed the graphene-based sensors for breath analysis during sleep, and made several design improvements to increase sensitivity.

“Thanks to the design changes we made, the sensors are able to detect different sleep states, while ignoring regular tossing and turning,” said Occhinpinti. “ ̽��ֱ��improved sensitivity also means that the smart garment does not need to be worn tightly around the neck, which many people would find uncomfortable. As long as the sensors are in contact with the skin, they provide highly accurate readings.”

̽��ֱ��researchers designed a machine learning model, called SleepNet, that uses the signals captured by the sensors to identify sleep states including nasal breathing, mouth breathing, snoring, teeth grinding, central sleep apnoea (CSA), and obstructive sleep apnoea (OSA). SleepNet is a ‘lightweight’ AI network, that reduces computational complexity to the point where it can be run on portable devices, without the need to connect to computers or servers.

“We pruned the AI model to the point where we could get the lowest computational cost with the highest degree of accuracy,” said Occhinpinti. “This way we are able to embed the main data processors in the sensors directly.”

̽��ֱ��smart pyjamas were tested on healthy patients and those with sleep apnoea, and were able to detect a range of sleep states with an accuracy of 98.6%. By treating the smart pyjamas with a special starching step, they were able to improve the durability of the sensors so they can be run through a regular washing machine.

̽��ֱ��most recent version of the smart pyjamas are also capable of wireless data transfer, meaning the sleep data can be securely transferred to a smartphone or computer.

“Sleep is so important to health, and reliable sleep monitoring can be key in preventative care,” said Occhipinti. “Since this garment can be used at home, rather than in a hospital or clinic, it can alert users to changes in their sleep that they can then discuss with their doctor. Sleep behaviours such as nasal versus mouth breathing are not typically picked up in an NHS sleep analysis, but it can be an indicator of disordered sleep.”

̽��ֱ��researchers are hoping to adapt the sensors for a range of health conditions or home uses, such as baby monitoring, and have been in discussions with different patient groups. They are also working to improve the durability of the sensors for long-term use.

̽��ֱ��research was supported in part by the EU Graphene Flagship, Haleon, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI).

Reference:
Chenyu Tang, Wentian Yi et al. ‘A deep learning-enabled smart garment for accurate and versatile monitoring of sleep conditions in daily life.’ PNAS (2025). DOI: 10.1073/pnas.2420498122

Researchers have developed comfortable, washable ‘smart pyjamas’ that can monitor sleep disorders such as sleep apnoea at home, without the need for sticky patches, cumbersome equipment or a visit to a specialist sleep clinic.

We need something that is comfortable and easy to use every night, but is accurate enough to provide meaningful information about sleep quality

Luigi Occhipinti

Illustration and photograph of 'smart pyjamas'

Yes

Cambridge to trial cutting-edge semiconductor technologies for wider use in major European project

sc604 — Tue, 10 Dec 2024 10:34:10 +0000

Photonic chips transmit and manipulate light instead of electricity, and offer significantly faster performance with lower power consumption than traditional electronic chips. 

̽��ֱ��Cambridge Graphene Centre and Cornerstone Photonics Innovation Centre at the ̽��ֱ�� of Southampton will partner with members from across Europe to host a pilot line, coordinated by the Institute of Photonic Sciences in Spain, combining state-of-the-art equipment and expertise from 20 research organisations.

̽��ֱ��PIXEurope consortium has been selected by the European Commission and Chips Joint Undertaking, a European initiative aiming to bolster the semiconductor industry by fostering collaboration between member states and the private sector. ̽��ֱ��consortium is supported by €380m in total funding.

̽��ֱ��UK participants will be backed by up to £4.2 million in funding from the Department of Science, Innovation and Technology (DSIT), match-funded by Horizon Europe. ̽��ֱ��UK joined the EU’s Chips Joint Undertaking in March 2024, allowing the country to collaborate more closely with European partners on semiconductor innovation.

̽��ֱ��new pilot line will combine state-of-the-art equipment and expertise from research organisations across 11 countries. It aims to encourage the adoption of cutting-edge photonic technologies across more industries to boost their efficiency.

Photonic chips are already essential across a wide range of applications, from tackling the unprecedented energy demands of datacentres, to enabling high-speed data transmission for mobile and satellite communications. In the future, these chips will become ever more important, unlocking new applications in healthcare, AI and quantum computing. 

Researchers at the Cambridge Graphene Centre will be responsible for the integration of graphene and related materials into photonic circuits for energy efficient, high-speed communications and quantum devices. “This may lead to life-changing products and services, with huge economic benefit for the UK and the world,” said Professor Andrea C. Ferrari, Director of the Cambridge Graphene Centre.

̽��ֱ��global market for photonic integrated circuits (PICs) production is expected to grow by more than 400% in the next 10 years. By the end of the decade, the global photonics market is expected to exceed €1,500bn, a figure comparable to the entire annual gross domestic product of Spain.

This growth is due to the demand from areas such as telecommunications, artificial intelligence, image sensing, automotive and mobility, medicine and healthcare, environmental care, renewable energy, defense and security, and a wide range of consumer applications.

̽��ֱ��combination of microelectronic chips and photonic chips provides the necessary features and specifications for these applications. ̽��ֱ��former are responsible for information processing by manipulating electrons within circuits based on silicon and its variants, while the latter uses photons in the visible and infrared spectrum ranges in various materials.

̽��ֱ��new pilot line aims to offer cutting-edge technological platforms, transforming and transferring innovative and disruptive integrated photonics processes and technologies to accelerate their industrial adoption. ̽��ֱ��objective is the creation of European-owned/made technology in a sector of capital importance for technological sovereignty, and the creation and maintenance of corresponding jobs in the UK and across Europe.

“My congratulations to Cornerstone and the Cambridge Graphene Centre on being selected to pioneer the new pilot line – taking a central role in driving semiconductor innovation to the next level, encouraging adoption of new technologies,” said Science Minister Lord Vallance. “ ̽��ֱ��UK laid the foundations of silicon photonics in the 1990s, and by pooling our expertise with partners across Europe we can address urgent global challenges including energy consumption and efficiency.”

“ ̽��ֱ��UK’s participation in the first Europe-wide photonics pilot line marks the start of the world’s first open access photonics integrated circuits ecosystem, stimulating new technology development with industry and catalyse disruptive innovation across the UK, while strengthening UK collaboration with top European institutions working in the field,” said Ferrari.

“PIXEurope is the first photonics pilot line that unifies the whole supply chain from design and fabrication, to testing and packaging, with technology platforms that will support a broad spectrum of applications,” said CORNERSTONE Coordinator Professor Calum Littlejohns. “I am delighted that CORNERSTONE will form a crucial part of this programme.”

̽��ֱ��Chips JU will also launch new collaborative R&D calls on a range of topics in early 2025. UK companies and researchers are eligible to participate.

̽��ֱ�� ̽��ֱ�� of Cambridge is one of two UK participants named as part of the PIXEurope consortium, a collaboration between research organisations from across Europe which will develop and manufacture prototypes of their products based on photonic chips.

Yes

Journeys of discovery: Steve Jackson and a life-saving cancer drug

lw355 — Mon, 15 Jul 2024 07:00:08 +0000

What excites Steve Jackson is understanding how biology works and why it sometimes goes wrong. But what galvanises him is knowing there are people alive today as a result of his discovery of how to create a cancer drug.

Shimmering seaweeds and algae antennae: sustainable energy solutions under the sea

sc604 — Thu, 22 Feb 2024 16:40:43 +0000

Funded by the European Union’s Horizon 2020 research and innovation programme, the Bio-inspired and Bionic materials for Enhanced Photosynthesis (BEEP) project, led by Professor Silvia Vignolini in the Yusuf Hamied Department of Chemistry, studied how marine organisms interact with light.

̽��ֱ��four-year sustainable energy project brought together nine research groups from across Europe and drew its inspiration from nature, in particular from the marine world, where organisms including algae, corals and sea slugs have evolved efficient ways to convert sunlight into energy. Harnessing these properties could aid in the development of new artificial and bionic photosynthetic systems.

Some of the brightest and most colourful materials in nature – such as peacock feathers, butterfly wings and opals – get their colour not from pigments or dyes, but from their internal structure alone. ̽��ֱ��colours our eyes perceive originate from the interaction between light and nanostructures at the surface of the material, which reflect certain wavelengths of light.

As part of the BEEP project, the team studied structural colour in marine species. Some marine algae species have nanostructures in their cell walls that can transmit certain wavelengths of visible light or change their structures to guide the light inside the cell. Little is known about the function of these structures, however: scientists believe they might protect the organisms from UV light or optimise light harvesting capabilities.

̽��ֱ��team studied the optical properties and light harvesting efficiency of a range of corals, sea-slugs, microalgae and seaweeds. By understanding the photonic and structural properties of these species, the scientists hope to design new materials for bio-photoreactors and bionic systems.

“We’re fascinated by the optical effects performed by these organisms,” said Maria Murace, a BEEP PhD candidate at Cambridge, who studies structural colour in seaweeds and marine bacteria. “We want to understand what the materials and the structures at the base of these colours are, which could lead to the development of green and sustainable alternatives to the conventional paints and toxic dyes we use today.”

BEEP also studied diatoms: tiny photosynthetic algae that live in almost every aquatic system on Earth and produce as much as half of the oxygen we breathe. ̽��ֱ��silica shells of these tiny algae form into stunning structures, but they also possess remarkable light-harvesting properties.

̽��ֱ��BEEP team engineered tiny light-harvesting antennae and attached them to diatom shells. “These antennae allowed us to gather the light that would otherwise not be harvested by the organism, which is converted and used for photosynthesis,” said Cesar Vicente Garcia, one of the BEEP PhD students, from the ̽��ֱ�� of Bari in Italy. “ ̽��ֱ��result is promising: diatoms grow more! This research could inspire the design of powerful bio-photoreactors, or even better

̽��ֱ��scientists engineered a prototype bio-photoreactor, consisting of a fully bio-compatible hydrogel which sustains the growth of microalgae and structural coloured bacteria. ̽��ֱ��interaction of these organisms is mutually beneficial, enhancing microalgal growth and increasing the volume of biomass produced, which could have applications in the biofuel production industry.

Alongside research, the network has organised several training and outreach activities, including talks and exhibitions for the public at science festivals in Italy, France and the UK.

“Society relies on science to drive growth and progress,” said Floriana Misceo, the BEEP network manager who coordinated outreach efforts. “It’s so important for scientists to share their research and help support informed discussion and debate because without it, misinformation can thrive, which is why training and outreach was an important part of this project.”

“Coordinating this project has been a great experience. I learned immensely from the other groups in BEEP and the young researchers,” said Vignolini. “ ̽��ֱ��opportunity to host researchers from different disciplines in the lab was instrumental in developing new skills and approaching problems from a different perspective.”

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under a Marie Skłodowska-Curie grant.

How could tiny antennae attached to tiny algae speed up the transition away from fossil fuels? This is one of the questions being studied by Cambridge researchers as they search for new ways to decarbonise our energy supply, and improve the sustainability of harmful materials such as paints and dyes.

BEEP

Seaweeds showing structural colour

Yes

Diamonds and rust help unveil ‘impossible’ quasi-particles

sc604 — Tue, 05 Dec 2023 10:02:43 +0000

Researchers led by the ̽��ֱ�� of Cambridge used a technique known as diamond quantum sensing to observe swirling textures and faint magnetic signals on the surface of hematite, a type of iron oxide.

̽��ֱ��researchers observed that magnetic monopoles in hematite emerge through the collective behaviour of many spins (the angular momentum of a particle). These monopoles glide across the swirling textures on the surface of the hematite, like tiny hockey pucks of magnetic charge. This is the first time that naturally occurring emergent monopoles have been observed experimentally.

̽��ֱ��research has also shown the direct connection between the previously hidden swirling textures and the magnetic charges of materials like hematite, as if there is a secret code linking them together. ̽��ֱ��results, which could be useful in enabling next-generation logic and memory applications, are reported in the journal Nature Materials.

According to the equations of James Clerk Maxwell, a giant of Cambridge physics, magnetic objects, whether a fridge magnet or the Earth itself, must always exist as a pair of magnetic poles that cannot be isolated.

“ ̽��ֱ��magnets we use every day have two poles: north and south,” said Professor Mete Atatüre, who led the research. “In the 19th century, it was hypothesised that monopoles could exist. But in one of his foundational equations for the study of electromagnetism, James Clerk Maxwell disagreed.”

Atatüre is Head of Cambridge’s Cavendish Laboratory, a position once held by Maxwell himself. “If monopoles did exist, and we were able to isolate them, it would be like finding a missing puzzle piece that was assumed to be lost,” he said.

About 15 years ago, scientists suggested how monopoles could exist in a magnetic material. This theoretical result relied on the extreme separation of north and south poles so that locally each pole appeared isolated in an exotic material called spin ice.

However, there is an alternative strategy to find monopoles, involving the concept of emergence. ̽��ֱ��idea of emergence is the combination of many physical entities can give rise to properties that are either more than or different to the sum of their parts.

Working with colleagues from the ̽��ֱ�� of Oxford and the National ̽��ֱ�� of Singapore, the Cambridge researchers used emergence to uncover monopoles spread over two-dimensional space, gliding across the swirling textures on the surface of a magnetic material.

̽��ֱ��swirling topological textures are found in two main types of materials: ferromagnets and antiferromagnets. Of the two, antiferromagnets are more stable than ferromagnets, but they are more difficult to study, as they don’t have a strong magnetic signature.

To study the behaviour of antiferromagnets, Atatüre and his colleagues use an imaging technique known as diamond quantum magnetometry. This technique uses a single spin – the inherent angular momentum of an electron – in a diamond needle to precisely measure the magnetic field on the surface of a material, without affecting its behaviour.

For the current study, the researchers used the technique to look at hematite, an antiferromagnetic iron oxide material. To their surprise, they found hidden patterns of magnetic charges within hematite, including monopoles, dipoles and quadrupoles.

“Monopoles had been predicted theoretically, but this is the first time we’ve actually seen a two-dimensional monopole in a naturally occurring magnet,” said co-author Professor Paolo Radaelli, from the ̽��ֱ�� of Oxford.

“These monopoles are a collective state of many spins that twirl around a singularity rather than a single fixed particle, so they emerge through many-body interactions. ̽��ֱ��result is a tiny, localised stable particle with diverging magnetic field coming out of it,” said co-first author Dr Hariom Jani, from the ̽��ֱ�� of Oxford.

“We’ve shown how diamond quantum magnetometry could be used to unravel the mysterious behaviour of magnetism in two-dimensional quantum materials, which could open up new fields of study in this area,” said co-first author Dr Anthony Tan, from the Cavendish Laboratory. “ ̽��ֱ��challenge has always been direct imaging of these textures in antiferromagnets due to their weaker magnetic pull, but now we’re able to do so, with a nice combination of diamonds and rust.”

̽��ֱ��study not only highlights the potential of diamond quantum magnetometry but also underscores its capacity to uncover and investigate hidden magnetic phenomena in quantum materials. If controlled, these swirling textures dressed in magnetic charges could power super-fast and energy-efficient computer memory logic.

̽��ֱ��research was supported in part by the Royal Society, the Sir Henry Royce Institute, the European Union, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI).

Reference:
K C Tan, Hariom Jani, Michael Högen et al. ‘Revealing Emergent Magnetic Charge in an Antiferromagnet with Diamond Quantum Magnetometry.’ Nature Materials (2023). DOI: 10.1038/s41563-023-01737-4.

For more information on energy-related research in Cambridge, please visit the Energy IRC, which brings together Cambridge’s research knowledge and expertise, in collaboration with global partners, to create solutions for a sustainable and resilient energy landscape for generations to come.

Researchers have discovered magnetic monopoles – isolated magnetic charges – in a material closely related to rust, a result that could be used to power greener and faster computing technologies.

If monopoles did exist, and we were able to isolate them, it would be like finding a missing puzzle piece that was assumed to be lost

Mete Atatüre

Anthony Tan and Michael Hoegen

Magnetic monopoles in hematite

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Solar-powered device produces clean water and clean fuel at the same time

sc604 — Mon, 13 Nov 2023 16:21:43 +0000

̽��ֱ��device, developed by researchers at the ̽��ֱ�� of Cambridge, could be useful in resource-limited or off-grid environments, since it works with any open water source and does not require any outside power.

It takes its inspiration from photosynthesis, the process by which plants convert sunlight into food. However, unlike earlier versions of the ‘artificial leaf’, which could produce green hydrogen fuel from clean water sources, this new device operates from polluted or seawater sources and can produce clean drinking water at the same time.

Tests of the device showed it was able to produce clean water from highly polluted water, seawater, and even from the River Cam in central Cambridge. ̽��ֱ��results are reported in the journal Nature Water.

“Bringing together solar fuels production and water purification in a single device is tricky,” said Dr Chanon Pornrungroj from Cambridge’s Yusuf Hamied Department of Chemistry, the paper’s co-lead author. “Solar-driven water splitting, where water molecules are broken down into hydrogen and oxygen, need to start with totally pure water because any contaminants can poison the catalyst or cause unwanted chemical side-reactions.”

“In remote or developing regions, where clean water is relatively scarce and the infrastructure necessary for water purification is not readily available, water splitting is extremely difficult,” said co-lead author Ariffin Mohamad Annuar. “A device that could work using contaminated water could solve two problems at once: it could split water to make clean fuel, and it could make clean drinking water.”

Pornrungroj and Mohamad Annuar, who are both members of Professor Erwin Reisner’s research group, came up with a design that did just that. They deposited a photocatalyst on a nanostructured carbon mesh that is a good absorber of both light and heat, generating the water vapour used by the photocatalyst to create hydrogen. ̽��ֱ��porous carbon mesh, treated to repel water, served both to help the photocatalyst float and to keep it away from the water below, so that contaminants do not interfere with its functionality.

In addition, the new device uses more of the Sun’s energy. “ ̽��ֱ��light-driven process for making solar fuels only uses a small portion of the solar spectrum – there’s a whole lot of the spectrum that goes unused,” said Mohamad Annuar.

̽��ֱ��team used a white, UV-absorbing layer on top of the floating device for hydrogen production via water splitting. ̽��ֱ��rest of the light in the solar spectrum is transmitted to the bottom of the device, which vaporises the water.

“This way, we’re making better use of the light – we get the vapour for hydrogen production, and the rest is water vapour,” said Pornrungroj. “This way, we’re truly mimicking a real leaf, since we’ve now been able to incorporate the process of transpiration.”

A device that can make clean fuel and clean water at once using solar power alone could help address the energy and the water crises facing so many parts of the world. For example, the indoor air pollution caused by cooking with ‘dirty’ fuels, such as kerosene, is responsible for more than three million deaths annually, according to the World Health Organization. Cooking with green hydrogen instead could help reduce that number significantly. And 1.8 billion people worldwide still lack safe drinking water at home.

“It’s such a simple design as well: in just a few steps, we can build a device that works well on water from a wide variety of sources,” said Mohamad Annuar.

“It’s so tolerant of pollutants, and the floating design allows the substrate to work in very cloudy or muddy water,” said Pornrungroj. “It’s a highly versatile system.”

“Our device is still a proof of principle, but these are the sorts of solutions we will need if we’re going to develop a truly circular economy and sustainable future,” said Reisner, who led the research. “ ̽��ֱ��climate crisis and issues around pollution and health are closely related, and developing an approach that could help address both would be a game-changer for so many people.”

̽��ֱ��research was supported in part by the European Commission’s Horizon 2020 programme, ̽��ֱ��European Research Council, the Cambridge Trust, the Petronas Education Sponsorship Programme, and the Winton Programme for the Physics of Sustainability. Erwin Reisner is a Fellow of St John’s College. Chanon Pornrungroj is a member of Darwin College, and Ariffin Mohamad Annuar is a member of Clare College.

Reference:
Chanon Pornrungroj, Ariffin Bin Mohamad Annuar et al. ‘Hybrid photothermal-photocatalyst sheets for solar-driven overall water splitting coupled to water purification.’ Nature Water (2023). DOI: 10.1038/s44221-023-00139-9

A floating, solar-powered device that can turn contaminated water or seawater into clean hydrogen fuel and purified water, anywhere in the world, has been developed by researchers.

These are the sorts of solutions we will need to develop a truly circular economy and sustainable future

Erwin Reisner

Chanon Pornrungroj

Device for making solar fuels on the River Cam near the Bridge of Sighs

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Switching ‘spin’ on and off (and up and down) in quantum materials at room temperature

sc604 — Wed, 16 Aug 2023 15:00:00 +0000

Spin is the term for the intrinsic angular momentum of electrons, which is referred to as up or down. Using the up/down spin states of electrons instead of the 0 and 1 in conventional computer logic could transform the way in which computers process information. And sensors based on quantum principles could vastly improve our abilities to measure and study the world around us.

An international team of researchers, led by the ̽��ֱ�� of Cambridge, has found a way to use particles of light as a ‘switch’ that can connect and control the spin of electrons, making them behave like tiny magnets that could be used for quantum applications.

̽��ֱ��researchers designed modular molecular units connected by tiny ‘bridges’. Shining a light on these bridges allowed electrons on opposite ends of the structure to connect to each other by aligning their spin states. Even after the bridge was removed, the electrons stayed connected through their aligned spins.

This level of control over quantum properties can normally only be achieved at ultra-low temperatures. However, the Cambridge-led team has been able to control the quantum behaviour of these materials at room temperature, which opens up a new world of potential quantum applications by reliably coupling spins to photons. ̽��ֱ��results are reported in the journal Nature.

Almost all types of quantum technology – based on the strange behaviour of particles at the subatomic level – involve spin. As they move, electrons usually form stable pairs, with one electron spin up and one spin down. However, it is possible to make molecules with unpaired electrons, called radicals. Most radicals are very reactive, but with careful design of the molecule, they can be made chemically stable.

“These unpaired spins change the rules for what happens when a photon is absorbed and electrons are moved up to a higher energy level,” said first author Sebastian Gorgon, from Cambridge’s Cavendish Laboratory. “We’ve been working with systems where there is one net spin, which makes them good for light emission and making LEDs.”

Gorgon is a member of Professor Sir Richard Friend’s research group, where they have been studying radicals in organic semiconductors for light generation, and identified a stable and bright family of materials a few years ago. These materials can beat the best conventional OLEDs for red light generation.

“Using tricks developed by different fields was important,” said Dr Emrys Evans from Swansea ̽��ֱ��, who co-led the research. “ ̽��ֱ��team has significant expertise from a number of areas in physics and chemistry, such as the spin properties of electrons and how to make organic semiconductors work in LEDs. This was critical for knowing how to prepare and study these molecules in the solid state, enabling our demonstration of quantum effects at room temperature.”

Organic semiconductors are the current state-of-the-art for lighting and commercial displays, and they could be a more sustainable alternative to silicon for solar cells. However, they have not yet been widely studied for quantum applications, such as quantum computing or quantum sensing.

“We’ve now taken the next big step and linked the optical and magnetic properties of radicals in an organic semiconductor,” said Gorgon. “These new materials hold great promise for completely new applications, since we’ve been able to remove the need for ultra-cold temperatures.”

“Knowing what electron spins are doing, let alone controlling them, is not straightforward, especially at room temperature,” said Friend, who co-led the research. “But if we can control the spins, we can build some interesting and useful quantum objects.”

̽��ֱ��researchers designed a new family of materials by first determining how they wanted the electron spins to behave. Using this bottom-up approach, they were able to control the properties of the end material by using a building block method and changing the ‘bridges’ between different modules of the molecule. These bridges were made of anthracene, a type of hydrocarbon.

For their ‘mix-and-match’ molecules, the researchers attached a bright light-emitting radical to an anthracene molecule. After a photon of light is absorbed by the radical, the excitation spreads out onto the neighbouring anthracene, causing three electrons to start spinning in the same way. When a further radical group is attached to the other side of the anthracene molecules, its electron is also coupled, bringing four electrons to spin in the same direction.

“In this example, we can switch on the interaction between two electrons on opposite ends of the molecule by aligning electron spins on the bridge absorbing a photon of light,” said Gorgon. “After relaxing back, the distant electrons remember they were together even after the bridge is gone.

“In these materials we’ve designed, absorbing a photon is like turning a switch on. ̽��ֱ��fact that we can start to control these quantum objects by reliably coupling spins at room temperature could open up far more flexibility in the world of quantum technologies. There’s a huge potential here to go in lots of new directions.”

“People have spent years trying to get spins to reliably talk to each other, but by starting instead with what we want the spins to do and then the chemists can design a molecule around that, we’ve been able to get the spins to align,” said Friend. “It’s like we’ve hit the Goldilocks zone where we can tune the spin coupling between the building blocks of extended molecules.”

̽��ֱ��advance was made possible through a large international collaboration – the materials were made in China, experiments were done in Cambridge, Oxford and Germany, and theory work was done in Belgium and Spain.

̽��ֱ��research was supported in part by the European Research Council, the European Union, the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI), and the Royal Society. Richard Friend is a Fellow of St John’s College, Cambridge.

Reference:
Sebastian Gorgon et al. ‘Reversible spin-optical interface in luminescent organic radicals.’ Nature (2023). DOI: 10.1038/s41586-023-06222-1

Researchers have found a way to control the interaction of light and quantum ‘spin’ in organic semiconductors, that works even at room temperature.

These new materials hold great promise for completely new applications, since we’ve been able to remove the need for ultra-cold temperatures

Sebastian Gorgon

Artist's impression of aligned spins in an organic semiconductor

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