̽��ֱ�� of Cambridge - semiconductor

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

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

Arm donates £3.5 million for Cambridge PhD students to study computer architecture and semiconductor design

skbf2 — Wed, 20 Nov 2024 13:05:14 +0000

̽��ֱ��first three students to be supported by the Arm donation will begin their studies at the new research centre in the autumn of 2025. They will be followed by another three students each year for the following four years.

Arm – the company building the future of computing with its global headquarters in Cambridge – is the first organisation to donate to the new CASCADE Research Centre, part of the Department of Computer Science and Technology.

“We’re very grateful to them for their generous support,” said Professor Timothy Jones, Director of the Centre. “As well as funding 15 PhD students over the next five years, Arm’s involvement is helping us realise our vision of a centre where research into addressing key challenges in this field is informed and supported by our industrial partners.This is extremely valuable to us as we work to make the Centre a destination for collaboration between companies, generating pre-competitive open-source artefacts and driving development of novel computer architectures.”

Richard Grisenthwaite, executive vice president and chief architect, Arm said: “Our long-standing commitment to the ̽��ֱ�� of Cambridge through this latest CASCADE funding highlights the vital collaboration between academia and industry as we embark on ground-breaking intent-based programming work to realize the future promise of AI through the next generation of processor designs."

“ ̽��ֱ��Centre has the potential to enable further technology innovation within the semiconductor industry and is an important part of Arm’s mission to build the future of computing.”

Jones added: "Computer architecture is a critical area of computing. It underpins today’s technologies and drives the next generation of computing systems. Here in the Department of Computer Science and Technology, we’re proud of our research and innovation in this area. And the recently published National Semiconductor Strategy underlined how vital such work is, showing that the UK is currently a leader in computer architecture."

"But to maintain this leading position, we need to invest in developing the research leaders of tomorrow. That's why we have established the new CASCADE Research Centre to fund PhD students working in this area, through support from industry. It is currently taking applications for its first cohort of students."

̽��ֱ��Centre will focus on research that addresses some of the grand challenges in computer architecture, design automation and semiconductors.

PhD students will work alongside researchers here who have expertise across the breadth of the area, encompassing the design and optimisation of general-purpose microprocessors, specialised accelerators, on-chip interconnect and memory systems, verification, compilation and networking, quantum architecture and resource estimation. This will allow them to explore the areas they are most passionate about, while addressing industry-relevant research.

Students receiving funding from Arm will be working in the general area of intent-based computing, researching systems that communicate what programs will do in the future so that the processor can make better decisions about how to execute them.

Arm was born in Cambridge in 1990 with the goal of changing the computing landscape. Its success since then in designing, architecting, and licensing high-performance, power-efficient CPUs — the 'brain' of all computers and many household and electronic devices — helped fuel the smartphone revolution and has made it a household name.

Arm has long had a research relationship with Cambridge ̽��ֱ��. Most notably, this has led to the development of new cybersecurity technology, focusing on innovative ways to design the architecture of a computer’s CPU to make software less vulnerable to security breaches.

Adapted from a news release published by the Department of Computer Science and Technology

Arm is donating £3.5 million to enable 15 PhD students over the next five years to study at CASCADE, the ̽��ֱ��'s new Computer Architecture and Semiconductor Design Centre.

Yuichiro Chino via Getty Images

Futuristic circuit board and semiconductor

Yes

A simple ‘twist’ improves the engine of clean fuel generation

sc604 — Wed, 24 Apr 2024 14:31:37 +0000

̽��ֱ��researchers, led by the ̽��ֱ�� of Cambridge, are developing low-cost light-harvesting semiconductors that power devices for converting water into clean hydrogen fuel, using just the power of the sun. These semiconducting materials, known as copper oxides, are cheap, abundant and non-toxic, but their performance does not come close to silicon, which dominates the semiconductor market.

However, the researchers found that by growing the copper oxide crystals in a specific orientation so that electric charges move through the crystals at a diagonal, the charges move much faster and further, greatly improving performance. Tests of a copper oxide light harvester, or photocathode, based on this fabrication technique showed a 70% improvement over existing state-of-the-art oxide photocathodes, while also showing greatly improved stability.

̽��ֱ��researchers say their results, reported in the journal Nature, show how low-cost materials could be fine-tuned to power the transition away from fossil fuels and toward clean, sustainable fuels that can be stored and used with existing energy infrastructure.

Copper (I) oxide, or cuprous oxide, has been touted as a cheap potential replacement for silicon for years, since it is reasonably effective at capturing sunlight and converting it into electric charge. However, much of that charge tends to get lost, limiting the material’s performance.

“Like other oxide semiconductors, cuprous oxide has its intrinsic challenges,” said co-first author Dr Linfeng Pan from Cambridge’s Department of Chemical Engineering and Biotechnology. “One of those challenges is the mismatch between how deep light is absorbed and how far the charges travel within the material, so most of the oxide below the top layer of material is essentially dead space.”

“For most solar cell materials, it’s defects on the surface of the material that cause a reduction in performance, but with these oxide materials, it’s the other way round: the surface is largely fine, but something about the bulk leads to losses,” said Professor Sam Stranks, who led the research. “This means the way the crystals are grown is vital to their performance.”

To develop cuprous oxides to the point where they can be a credible contender to established photovoltaic materials, they need to be optimised so they can efficiently generate and move electric charges – made of an electron and a positively-charged electron ‘hole’ – when sunlight hits them.

One potential optimisation approach is single-crystal thin films – very thin slices of material with a highly-ordered crystal structure, which are often used in electronics. However, making these films is normally a complex and time-consuming process.

Using thin film deposition techniques, the researchers were able to grow high-quality cuprous oxide films at ambient pressure and room temperature. By precisely controlling growth and flow rates in the chamber, they were able to ‘shift’ the crystals into a particular orientation. Then, using high temporal resolution spectroscopic techniques, they were able to observe how the orientation of the crystals affected how efficiently electric charges moved through the material.

“These crystals are basically cubes, and we found that when the electrons move through the cube at a body diagonal, rather than along the face or edge of the cube, they move an order of magnitude further,” said Pan. “ ̽��ֱ��further the electrons move, the better the performance.”

“Something about that diagonal direction in these materials is magic,” said Stranks. “We need to carry out further work to fully understand why and optimise it further, but it has so far resulted in a huge jump in performance.” Tests of a cuprous oxide photocathode made using this technique showed an increase in performance of more than 70% over existing state-of-the-art electrodeposited oxide photocathodes.

“In addition to the improved performance, we found that the orientation makes the films much more stable, but factors beyond the bulk properties may be at play,” said Pan.

̽��ֱ��researchers say that much more research and development is still needed, but this and related families of materials could have a vital role in the energy transition.

“There’s still a long way to go, but we’re on an exciting trajectory,” said Stranks. “There’s a lot of interesting science to come from these materials, and it’s interesting for me to connect the physics of these materials with their growth, how they form, and ultimately how they perform.”

̽��ֱ��research was a collaboration with École Polytechnique Fédérale de Lausanne, Nankai ̽��ֱ�� and Uppsala ̽��ֱ��. ̽��ֱ��research was supported in part by the European Research Council, the Swiss National Science Foundation, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Sam Stranks is Professor of Optoelectronics in the Department of Chemical Engineering and Biotechnology, and a Fellow of Clare College, Cambridge.

Reference:
Linfeng Pan, Linjie Dai et al. ‘High carrier mobility along the [111] orientation in Cu2O photoelectrodes.’ Nature (2024). DOI: 10.1038/s41586-024-07273-8

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 found a way to super-charge the ‘engine’ of sustainable fuel generation – by giving the materials a little twist.

orange via Getty Images

Abstract orange swirls

Yes

Three Cambridge researchers awarded Royal Academy of Engineering Chair in Emerging Technologies

sc604 — Thu, 14 Mar 2024 11:06:52 +0000

From atomically thin semiconductors for more energy-efficient electronics, to harnessing the power of the sun by upcycling biomass and plastic waste into sustainable chemicals, their research encompasses a variety of technological advances with the potential to deliver wide-ranging benefits.

Funded by the UK Department for Science, Innovation and Technology, the Academy’s Chair in Emerging Technologies scheme aims to identify global research visionaries and provide them with long-term support. Each £2,500,000 award covers employment and research costs, enabling each researcher to focus on advancing their technology to application in a strategic manner for up to 10 years.

Since 2017, the Chair in Emerging Technologies programme has awarded over £100 million to Chairs in 16 universities located across the UK. Of the four Chairs awarded in this round, three were awarded to Cambridge researchers.

Professor Manish Chhowalla FREng, from the Department of Materials Science and Metallurgy, is developing ultra-low-power electronics based on wafer-scale manufacture of atomically thin (or 2D) semiconductors. ̽��ֱ��atomically thin nature of the 2D semiconductors makes them ideal for energy-efficient electronics. To reap their benefits, complementary metal oxide semiconductor processes will be developed for integration into ultra-low power devices.

Professor Nic Lane and his team at the Department of Computer Science and Technology, are working to make the development of AI more democratic by focusing on AI methods that are less centralised and more collaborative, and offer better privacy protection.

Their project, nicknamed DANTE, aims to encourage wider and more active participation across society in the development and adoption of AI techniques.

“Artificial intelligence (AI) is evolving towards a situation where only a handful of the largest companies in the world can participate,” said Lane. “Given the importance of this technology to society this trajectory must be changed. We aim to invent, popularise and commercialise core new scientific breakthroughs that will enable AI technology in the future to be far more collaborative, distributed and open than it is today.”

̽��ֱ��project will focus on developing decentralised forms of AI that facilitate the collaborative study, invention, development and deployment of machine learning products and methods, primarily between collections of companies and organisations. An underlying mission of DANTE is to facilitate advanced AI technology remaining available for adoption in the public sphere, for example in hospitals, public policy, and energy and transit infrastructure.

Professor Erwin Reisner, from the Yusuf Hamied Department of Chemistry, is developing a technology, called solar reforming, that creates sustainable fuels and chemicals from biomass and plastic waste. This solar-powered technology uses only waste, water and air as ingredients, and the sun powers a catalyst to produce green hydrogen fuel and platform chemicals to decarbonise the transport and chemical sectors. A recent review in Nature Reviews Chemistry gives an overview of plans for the technology.

“ ̽��ֱ��generous long-term support provided by the Royal Academy of Engineering will be the critical driver for our ambitions to engineer, scale and ultimately commercialise our solar chemical technology,” said Reisner. “ ̽��ֱ��timing for this support is perfect, as my team has recently demonstrated several prototypes for upcycling biomass and plastic waste using sunlight, and we have excellent momentum to grasp the opportunities arising from developing these new technologies. I also hope to use this Chair to leverage further support to establish a circular chemistry centre in Cambridge to tackle our biggest sustainability challenges.”

“I am excited to announce this latest round of Chairs in Emerging Technology,” said Dr Andrew Clark, Executive Director, Programmes, at the Royal Academy of Engineering. “ ̽��ֱ��mid-term reviews of the previous rounds of Chairs are providing encouraging evidence that long-term funding of this nature helps to bring the groundbreaking and influential ideas of visionary engineers to fruition. I look forward to seeing the impacts of these four exceptionally talented individuals.”

Three Cambridge researchers – Professors Manish Chhowalla, Nic Lane and Erwin Reisner – have each been awarded a Royal Academy of Engineering Chair in Emerging Technologies, to develop emerging technologies with high potential to deliver economic and social benefits to the UK.

̽��ֱ�� of Cambridge

L-R: Manish Chhowalla, Nic Lane, Erwin Reisner

Yes

£11m semiconductor research centre could be key player in UK’s net zero mission

sc604 — Tue, 13 Feb 2024 13:24:00 +0000

Semiconductors, also known as microchips, are a key component in nearly every electrical device from mobile phones and medical equipment to electric vehicles.

They are increasingly being recognised as an area of global strategic significance due to the integral role they play in net zero, AI and quantum technology.

Co-created and delivered with industry, the REWIRE IKC is led by the ̽��ֱ�� of Bristol, in partnership with Cambridge and Warwick Universities.

̽��ֱ��IKC will accelerate the UK’s ambition for net zero by transforming the next generation of high-voltage electronic devices using wide/ultra-wide bandgap (WBG/UWBG) compound semiconductors.

̽��ֱ��project is being led by Professor Martin Kuball and his team at the ̽��ֱ�� of Bristol. Cambridge members of the IKC team include Professors Rachel Oliver, Florin Udrea and Teng Long.

̽��ֱ��centre will advance the next generation of semiconductor power device technologies and enhance the security of the UK’s semiconductor supply chain.

Compound semiconductor WBG/UWBG devices have been recognised in the UK National Semiconductor Strategy as key elements to support the net zero economy through the development of high voltage and low energy-loss power electronic technology.

They are essential building blocks for developing all-electric trains, ships and heavy goods electric vehicles, better charging infrastructure, renewable energy and High Voltage Direct Current grid connections, as well as intelligent power distribution and energy supplies to telecommunication networks and data centres.

“Power devices are at the centre of all power electronic systems and pave the way for more efficient and compact power electronic systems, reducing energy loss,” said Kuball. “ ̽��ֱ��REWIRE IKC will focus on power conversion of wind energy, electric vehicles, smart grids, high-temperature applications, device and packaging, and improving the efficiency of semiconductor device manufacture.”

Our home electrical supply is at 240 Volts, but to handle the power from offshore wind turbines, devices will have to operate at thousands of Volts. These very high voltages can easily damage the materials normally used in power electronics.

“Newly emerging ultra-wide bandgap materials have properties which enable them to handle very large voltages more easily,” said Oliver, Director of the Cambridge Centre for Gallium Nitride. “ ̽��ֱ��devices based on these materials will waste less energy and be smaller, lighter and cheaper. ̽��ֱ��same materials can also withstand high temperatures and doses of radiation, which means they can be used to enable other new electricity generation technologies, such as fusion energy.”

“ ̽��ֱ��REWIRE IKC will play a prominent role within the UK’s semiconductor strategy, in cementing the UK’s place as a leader in compound semiconductor research and development, developing IP to be exploited here in the UK, rebuilding the UK semiconductor supply chain, and training the next generation of semiconductor materials scientists and engineers,” said Professor Peter Gammon from the ̽��ֱ�� of Warwick.

Industry partners in the REWIRE IKC include Ampaire, BMW, Bosch, Cambridge GaN Devices (CGD), Element-Six Technologies, General Electric, Hitachi Energy, IQE, Oxford Instruments, Siemens, ST Microelectronics and Toshiba.

REWIRE is one of two new IKCs announced being funded by the Engineering and Physical Sciences Research Council (EPSRC) and Innovate UK, both part of UK Research and Innovation. ̽��ֱ��second IKC at the ̽��ֱ�� of Southampton will improve development and commercialisation of silicon photonics technologies in the UK.

“This investment marks a crucial step in advancing our ambitions for the semiconductor industry, with these centres helping bring new technologies to market in areas like net zero and AI, rooting them right here in the UK,” said Minister for Tech and the Digital Economy Saqib Bhatti. “Just nine months into delivering on the National Semiconductor Strategy, we’re already making rapid progress towards our goals. This isn’t just about fostering growth and creating high-skilled jobs, it's about positioning the UK as a hub of global innovation, setting the stage for breakthroughs that have worldwide impact.”

Adapted from a ̽��ֱ�� of Bristol media release.

̽��ֱ�� ̽��ֱ�� of Cambridge is a partner in the new £11m Innovation and Knowledge Centre (IKC) REWIRE, set to deliver pioneering semiconductor technologies and new electronic devices.

Yuichiro Chino via Getty Images

Robot arms and semiconductor wafer

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

̽��ֱ��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

Smart lighting system based on quantum dots more accurately reproduces daylight

sc604 — Wed, 03 Aug 2022 09:00:00 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, designed the next-generation smart lighting system using a combination of nanotechnology, colour science, advanced computational methods, electronics and a unique fabrication process.

̽��ֱ��team found that by using more than the three primary lighting colours used in typical LEDs, they were able to reproduce daylight more accurately. Early tests of the new design showed excellent colour rendering, a wider operating range than current smart lighting technology, and wider spectrum of white light customisation. ̽��ֱ��results are reported in the journal Nature Communications.

As the availability and characteristics of ambient light are connected with wellbeing, the widespread availability of smart lighting systems can have a positive effect on human health since these systems can respond to individual mood. Smart lighting can also respond to circadian rhythms, which regulate the daily sleep-wake cycle, so that light is reddish-white in the morning and evening, and bluish-white during the day.

When a room has sufficient natural or artificial light, good glare control, and views of the outdoors, it is said to have good levels of visual comfort. In indoor environments under artificial light, visual comfort depends on how accurately colours are rendered. Since the colour of objects is determined by illumination, smart white lighting needs to be able to accurately express the colour of surrounding objects. Current technology achieves this by using three different colours of light simultaneously.

Quantum dots have been studied and developed as light sources since the 1990s, due to their high colour tunability and colour purity. Due their unique optoelectronic properties, they show excellent colour performance in both wide colour controllability and high colour rendering capability.

̽��ֱ��Cambridge researchers developed an architecture for quantum-dot light-emitting diodes (QD-LED) based next-generation smart white lighting. They combined system-level colour optimisation, device-level optoelectronic simulation, and material-level parameter extraction.

̽��ֱ��researchers produced a computational design framework from a colour optimisation algorithm used for neural networks in machine learning, together with a new method for charge transport and light emission modelling.

̽��ֱ��QD-LED system uses multiple primary colours – beyond the commonly used red, green and blue – to more accurately mimic white light. By choosing quantum dots of a specific size – between three and 30 nanometres in diameter – the researchers were able to overcome some of the practical limitations of LEDs and achieve the emission wavelengths they needed to test their predictions.

̽��ֱ��team then validated their design by creating a new device architecture of QD-LED based white lighting. ̽��ֱ��test showed excellent colour rendering, a wider operating range than current technology, and a wide spectrum of white light shade customisation.

̽��ֱ��Cambridge-developed QD-LED system showed a correlated colour temperature (CCT) range from 2243K (reddish) to 9207K (bright midday sun), compared with current LED-based smart lights which have a CCT between 2200K and 6500K. ̽��ֱ��colour rendering index (CRI) – a measure of colours illuminated by the light in comparison to daylight (CRI=100) – of the QD-LED system was 97, compared to current smart bulb ranges, which are between 80 and 91.

̽��ֱ��design could pave the way to more efficient, more accurate smart lighting. In an LED smart bulb, the three LEDs must be controlled individually to achieve a given colour. In the QD-LED system, all the quantum dots are driven by a single common control voltage to achieve the full colour temperature range.

“This is a world-first: a fully optimised, high-performance quantum-dot-based smart white lighting system,” said Professor Jong Min Kim from Cambridge’s Department of Engineering, who co-led the research. “This is the first milestone toward the full exploitation of quantum-dot-based smart white lighting for daily applications.”

“ ̽��ֱ��ability to better reproduce daylight through its varying colour spectrum dynamically in a single light is what we aimed for,” said Professor Gehan Amaratunga, who co-led the research. “We achieved it in a new way through using quantum dots. This research opens the way for a wide variety of new human responsive lighting environments.”

̽��ֱ��structure of the QD-LED white lighting developed by the Cambridge team is scalable to large area lighting surfaces, as it is made with a printing process and its control and drive is similar to that in a display. With standard point source LEDs requiring individual control this is a more complex task.

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

Reference:
Chatura Samarakoon et al. ‘Optoelectronic System and Device Integration for Quantum-Dot Light-Emitting Diode White Lighting with Computational Design Framework.’ Nature Communications (2022). DOI: 10.1038/s41467-022-31853-9

Researchers have designed smart, colour-controllable white light devices from quantum dots – tiny semiconductors just a few billionths of a metre in size – which are more efficient and have better colour saturation than standard LEDs, and can dynamically reproduce daylight conditions in a single light.

This research opens the way for a wide variety of new human-responsive lighting environments

Gehan Amaratunga

Yaorusheng via Getty Images

Long exposure light painting

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