探花直播 of Cambridge - light-emitting diode (LED)

Spinning, twisted light could power next-generation electronics

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

探花直播researchers, led by the 探花直播 of Cambridge and the Eindhoven 探花直播 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.

探花直播semiconductor they developed emits circularly polarised light鈥攎eaning the light carries information about the 鈥榟andedness鈥� of electrons. 探花直播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. 探花直播chiral semiconductor developed by the researchers naturally emits light in a way that could reduce these losses, making screens brighter and more energy-efficient.

鈥淲hen I started working with organic semiconductors, many people doubted their potential, but now they dominate display technology,鈥� said Professor Sir Richard Friend from Cambridge鈥檚 Cavendish Laboratory, who co-led the research. 鈥淯nlike rigid inorganic semiconductors, molecular materials offer incredible flexibility鈥攁llowing us to design entirely new structures, like chiral LEDs. It鈥檚 like working with a Lego set with every kind of shape you can imagine, rather than just rectangular bricks.鈥�

探花直播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.

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

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.

鈥淲e鈥檝e 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,鈥� said co-first author Rituparno Chowdhury, from Cambridge鈥檚 Cavendish Laboratory. 鈥淭his provides a practical way to create circularly polarised LEDs, something that has long eluded the field.鈥�

探花直播work is part of a decades-long collaboration between Friend鈥檚 research group and the group of Professor Bert Meijer from the Eindhoven 探花直播 of Technology. 鈥淭his is a real breakthrough in making a chiral semiconductor,鈥� said Meijer. 鈥淏y carefully designing the molecular structure, we鈥檝e coupled the chirality of the structure to the motion of the electrons and that鈥檚 never been done at this level before.鈥�

探花直播chiral semiconductors represent a step forward in the world of organic semiconductors, which now support an industry worth over $60 billion (about 拢45 billion). Beyond displays, this development also has implications for quantum computing and spintronics鈥攁 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.

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

Reference

Rituparno Chowdhury, Marco D聽Preuss et al. 鈥�Circularly polarized electroluminescence from chiral supramolecular semiconductor thin films.鈥� 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鈥檚 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

探花直播text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright 漏探花直播 of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways 鈥� 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

Lights could be the future of the internet and data transmission

Anonymous — Tue, 25 Jul 2023 14:38:40 +0000

New internet technologies are being rapidly refined, and LED-based communication links are expected to be used in services and scenarios including Light-fidelity (Li-Fi), underwater communications, moderate- to high-speed photonic connections and various 鈥業nternet of Things鈥� (IoT) devices.

A study, led by the Universities of Surrey and Cambridge and published in the journal Nature Photonics, has investigated how to release high-speed photonic sources using materials known as metal-halide perovskites. These semiconductors are studied with LEDs for their excellent optoelectronic properties and low-cost processing methods.

鈥淚oT devices have the potential to add significant value to industry and the global economy,鈥� said corresponding author Dr Wei Zhang from the 探花直播 of Surrey. 鈥淚n this market, costs and compatibility are often prioritised over data transmission speed and scientists are looking for alternative ways to reduce energy consumption per bit and improve compactness while simultaneously working on improving the speed of data connection.

鈥淚n our study, we have shown how metal-halide perovskites could provide a cost-efficient and powerful solution to make LEDs which have enormous potential to increase their bandwidths into the gigahertz levels.

鈥淥ur investigations will accelerate the development of high-speed perovskite photodetectors and continuous wave-pumped perovskite lasers, opening up new avenues for advancements in optoelectronic technologies.鈥�

鈥淭his is a significant step toward perovskite light sources for next-generation data communications,鈥� said co-first author Hao Wang, a PhD candidate in Cambridge鈥檚 Department of Engineering. 鈥淚t also paves the way for the integration of perovskites with micro-electronics platforms, presenting new opportunities for seamless integration and advancement in the field of data communications.鈥�

探花直播project involved researchers from Oxford, Bath, Warwick, UCL, EMPA and UESTC.

Reference:
Aobo Ren, Hao Wang et al. 鈥�High-bandwidth perovskite photonic sources on silicon.鈥� Nature Photonics (2023). DOI: 10.1038/s41566-023-01242-9

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

Adapted from a 探花直播 of Surrey press release.

Fast data transmission could be delivered in homes and offices through light emitting diode (LED) bulbs, complementing existing communication technologies and networks.

This is a significant step toward perovskite light sources for next-generation data communications

Hao Wang

Yaorusheng via Getty Images

Abstract colourful background

探花直播text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright 漏探花直播 of Cambridge and licensors/contributors as identified.聽 All rights reserved. We make our image and video content available in a number of ways 鈥� 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

探花直播researchers, from the 探花直播 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.

探花直播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. 探花直播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.

探花直播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.

探花直播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.

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

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

探花直播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. 探花直播colour rendering index (CRI) 鈥� a measure of colours illuminated by the light in comparison to daylight (CRI=100) 鈥� of the QD-LED system was 97, compared to current smart bulb ranges, which are between 80 and 91.

探花直播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.

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

鈥� 探花直播ability to better reproduce daylight through its varying colour spectrum dynamically in a single light is what we aimed for,鈥� said Professor Gehan Amaratunga, who co-led the research. 鈥淲e 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.鈥�

探花直播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.

探花直播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).

聽

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

Researchers have designed smart, colour-controllable white light devices from quantum dots 鈥� tiny semiconductors just a few billionths of a metre in size 鈥� 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

探花直播text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright 漏探花直播 of Cambridge and licensors/contributors as identified.聽 All rights reserved. We make our image and video content available in a number of ways 鈥� 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

LEDs and smartphone screens could be made from next-generation glass

sc604 — Fri, 29 Oct 2021 15:42:21 +0000

探花直播international team of researchers has developed technology for next-generation composite glass, for use in lighting LEDs, smartphones, TVs and computer screens.

探花直播materials are based on materials called lead-halide perovskites, which can trap light and store energy, like miniature solar panels.

探花直播results, published in the journal Science, could enable the manufacture of glass screens that are less prone to cracking, but also deliver crystal clear image quality.

探花直播results are a step forward in perovskite nanocrystal technology as previously, researchers were only able to produce this technology in the bone-dry atmosphere of a laboratory setting.

鈥淭hese nanocrystals are extremely sensitive to light, heat, air and water 鈥� even water vapour in our air would kill the current devices in a matter of minutes,鈥� said Dr Jingwei Hou from the 探花直播 of Queensland (UQ), the paper鈥檚 first author.

探花直播team of chemical engineers and material scientists has developed a process to wrap or bind the nanocrystals in porous glass. This process is key to stabilising the materials, enhancing their efficiency and preventing the toxic lead ions from leaching out from the materials.

鈥淚t was surprising to see the retention of the high temperature functional form in the glass,鈥� said co-senior author Dr Thomas Bennett from Cambridge鈥檚 Department of Materials Science and Metallurgy. 鈥淭his is an example of how fundamental science leads to fantastic discoveries and a possible real-life application of metal-organic framework glasses.鈥�

探花直播researchers say the technology is scalable and opens the door for many potential applications.

鈥淎t present QLED or quantum dot light-emitting diode screens are considered the top performer for image display and performance,鈥� said Hou. 鈥淭his research will enable us to improve on this nanocrystal technology by offering stunning picture quality and strength.鈥�

鈥淣ot only can we make these nanocrystals more robust but we can tune their opto-electronic properties with fantastic light emission efficiency and highly desirable white light LEDs.鈥� said co-author Professor Vicki Chen, also from UQ. 鈥淭his discovery opens up a new generation of nanocrystal-glass composites for energy conversion and catalysis.鈥�

探花直播researchers say that a lot of optimisation work still needs to be carried out before any products based on the material could be made commercially available. 鈥淭here are a huge amount of different combinations and it鈥檚 definitely going to be a big effort to determine which components seem to give the best combinations,鈥� said Bennett.

探花直播research is a collaborative effort from UQ, the 探花直播 of Leeds, Universite虂 Paris-Saclay and the 探花直播 of Cambridge.

Reference:
Jingwei Hou et al. 鈥�Liquid-phase sintering of lead halide perovskites and metal-organic framework glasses.鈥� Science (2021). DOI: 10.1126/science.abf4460

Adapted from a UQ press release.

Cracked and blurry phone screens could someday be a thing of the past, suggests a new study from the 探花直播 of Cambridge and the 探花直播 of Queensland, Australia.

This is an example of how fundamental science leads to fantastic discoveries and possible real-life applications

Thomas Bennett

探花直播探花直播 of Queensland

Luminating composite glass

Yes

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

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

探花直播researchers, led by the 探花直播 of Cambridge and the Technical 探花直播 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. 聽

This 鈥榓tom swapping鈥�, or doping, causes the charge carriers to get stuck in a specific part of the material鈥檚 crystal structure, where they recombine and emit light. 探花直播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. 探花直播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.

探花直播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 鈥榪uantum dots鈥� are highly luminescent materials: the first high-brilliance QLED TVs incorporating quantum dots recently came onto the market.

探花直播Cambridge researchers, working with Daniel Congreve鈥檚 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 鈥� swapping lead for manganese ions 鈥� and found the luminescence of the quantum dots tripled.

A detailed investigation using laser spectroscopy revealed the origin of this observation. 鈥淲e found that the charges collect together in the regions of the crystals that we doped,鈥� said Sascha Feldmann from Cambridge鈥檚 Cavendish Laboratory, the study鈥檚 first author. 鈥淥nce localised, those energetic charges can meet each other and recombine to emit light in a very efficient manner.鈥�

鈥淲e 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,鈥� said senior author Felix Deschler, who is jointly affiliated at the Cavendish and the Walter Schottky Institute at the Technical 探花直播 of Munich.

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

聽

Reference:
Sascha Feldmann et al. 鈥�Charge carrier localization in doped perovskite nanocrystals enhances radiative recombination.鈥�, 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鈥檚 impression of glowing halide perovskite nanocrystals

Yes

New efficiency record set for perovskite LEDs

sc604 — Mon, 05 Nov 2018 16:00:56 +0000

Compared to OLEDs, which are widely used in high-end consumer electronics, the perovskite-based LEDs, developed by researchers at the 探花直播 of Cambridge, can be made at much lower costs, and can be tuned to emit light across the visible and near-infrared spectra with high colour purity.

探花直播researchers have engineered the perovskite layer in the LEDs to show close to 100% internal luminescence efficiency, opening up future applications in display, lighting and communications, as well as next-generation solar cells.

These perovskite materials are of the same type as those found to make highly efficient solar cells that could one day replace commercial silicon solar cells. While perovskite-based LEDs have already been developed, they have not been nearly as efficient as conventional OLEDs at converting electricity into light.

Earlier hybrid perovskite LEDs, first developed by Professor Sir Richard Friend鈥檚 group at the 探花直播鈥檚 Cavendish Laboratory four years ago, were promising, but losses from the perovskite layer, caused by tiny defects in the crystal structure, limited their light-emission efficiency.

Now, Cambridge researchers from the same group and their collaborators have shown that by forming a composite layer of the perovskites together with a polymer, it is possible to achieve much higher light-emission efficiencies, close to the theoretical efficiency limit of thin-film OLEDs. Their results are reported in the journal Nature Photonics.

鈥淭his perovskite-polymer structure effectively eliminates non-emissive losses, the first time this has been achieved in a perovskite-based device,鈥� said Dr Dawei Di from Cambridge鈥檚 Cavendish Laboratory, one of the corresponding authors of the paper. 鈥淏y blending the two, we can basically prevent the electrons and positive charges from recombining via the defects in the perovskite structure.鈥�

探花直播perovskite-polymer blend used in the LED devices, known as a bulk heterostructure, is made of two-dimensional and three-dimensional perovskite components and an insulating polymer. When an ultra-fast laser is shone on the structures, pairs of electric charges that carry energy move from the 2D regions to the 3D regions in a trillionth of a second: much faster than earlier layered perovskite structures used in LEDs. Separated charges in the 3D regions then recombine and emit light extremely efficiently.

鈥淪ince the energy migration from 2D regions to 3D regions happens so quickly, and the charges in the 3D regions are isolated from the defects by the polymer, these mechanisms prevent the defects from getting involved, thereby preventing energy loss,鈥� said Di.

鈥� 探花直播best external quantum efficiencies of these devices are higher than 20% at current densities relevant to display applications, setting a new record for perovskite LEDs, which is a similar efficiency value to the best OLEDs on the market today,鈥� said Baodan Zhao, the paper鈥檚 first author.

While perovskite-based LEDs are beginning to rival OLEDs in terms of efficiency, they still need better stability if they are to be adopted in consumer electronics. When perovskite-based LEDs were first developed, they had a lifetime of just a few seconds. 探花直播LEDs developed in the current research have a half-life close to 50 hours, which is a huge improvement in just four years, but still nowhere near the lifetimes required for commercial applications, which will require an extensive industrial development programme. 鈥淯nderstanding the degradation mechanisms of the LEDs is a key to future improvements,鈥� said Di.

探花直播research was funded by the Engineering and Physical Sciences Research Council (EPSRC) and the European Research Council (ERC).

Reference:
Baodan Zhao et al. 鈥�High-efficiency perovskite-polymer bulk heterostructure light-emitting diodes.鈥� Nature Photonics (2018). DOI: 10.1038/s41566-018-0283-4鈥�

A bold response to the world鈥檚 greatest challenge
探花直播探花直播 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 探花直播鈥檚 research and policy expertise, developing solutions that work for our lives, our society and our biosphere.

Researchers have set a new efficiency record for LEDs based on perovskite semiconductors, rivalling that of the best organic LEDs (OLEDs).聽

Artistic impression of the perovskite-polymer heterostructure used in LEDs

Yes

Ultra-thin quantum LEDs could accelerate development of quantum networks

sc604 — Fri, 07 Oct 2016 15:26:04 +0000

Ultra-thin quantum light emitting diodes (LEDs) 鈥� made of layered materials just a few atoms thick 鈥� have been developed by researchers at the 探花直播 of Cambridge. Constructed of layers of different ultra-thin materials, the devices could be used in the development of new computing and sensing technologies. 探花直播ability to produce single photons using only electrical current is an important step towards building quantum networks on compact chips.

探花直播devices are constructed of thin layers of different materials stacked together: graphene, boron nitride and transition metal dichalcogenides (TMDs). 探花直播TMD layer contains regions where electrons and electron vacancies, or holes, are tightly confined. When an electron fills an electron vacancy that sits at a lower energy than the electron, the energy difference is released as a photon, a particle of light. In the LED devices, a voltage pushes electrons through the device, where they fill the holes and emit single photons.

A computer built on the principles of quantum mechanics would be both far more powerful and more secure than current technologies, and would be capable of performing calculations that cannot be performed otherwise. However, in order to make such a device possible, researchers need to develop reliable methods of electrically generating single, indistinguishable photons as carriers of information across quantum networks.

探花直播ultra-thin platform developed by the Cambridge researchers offers high levels of tunability, design freedom, and integration capabilities. Typically, single photon generation requires large-scale optical set-ups with several lasers and precise alignment of optical components. This new research brings on-chip single photon emission for quantum communication a step closer. 探花直播results are reported in the journal Nature Communications.

鈥淯ltimately, we need fully integrated devices that we can control by electrical impulses, instead of a laser that focuses on different segments of an integrated circuit,鈥� said Professor Mete Atat眉re of Cambridge鈥檚 Cavendish Laboratory, one of the paper鈥檚 senior authors. 鈥淔or quantum communication with single photons, and quantum networks between different nodes, we want to be able to just drive current and get light out. There are many emitters that are optically excitable, but only a handful are electrically driven.鈥�

探花直播layered nature of TMDs makes them ideal for use in ultra-thin structures on chips. They also offer an advantage over some other single-photon emitters for feasible and effective integration into nanophotonic circuits.

With this research, quantum emitters are now seen in another TMD material, namely tungsten disulphide (WS₂). 鈥淲e chose WS₂ because we wanted to see if different materials offered different parts of the spectra for single photon emission,鈥� said Atat眉re, who is a Fellow of St John's College. 鈥淲ith this, we have shown that the quantum emission is not a unique feature of WS₂, which suggests that many other layered materials might be able to host quantum dot-like features as well.鈥�

鈥淲e are just scratching the surface of the many possible applications of devices prepared by combining graphene with other materials,鈥� said senior co-author Professor Andrea Ferrari, Director of the Cambridge Graphene. 鈥淚n this case, not only have we demonstrated controllable photon sources, but we have also shown that the field of quantum technologies can greatly benefit from layered materials. Many more exciting results and applications will surely follow.鈥�

Reference:
C. Palacios-Berraquero et al. 鈥�Atomically thin quantum light emitting diodes.鈥� Nature Communications (2016). DOI: 10.1038/ncomms12978

Researchers have developed all-electrical ultra-thin quantum LEDs, which have potential as on-chip photon sources in quantum information applications, including quantum networks for quantum computers.聽

Ultimately, we need fully integrated devices that we can control by electrical impulses.

Mete Atature

Microscope image of a quantum LED device showing bright quantum emitter generating a stream of single photons.

探花直播text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

LEDs made from 鈥榳onder material鈥� perovskite

sc604 — Tue, 05 Aug 2014 08:51:46 +0000

A hybrid form of perovskite - the same type of material which has recently been found to make highly efficient solar cells that could one day replace silicon - has been used to make low-cost, easily manufactured LEDs, potentially opening up a wide range of commercial applications in future, such as flexible colour displays.

This particular class of semiconducting perovskites have generated excitement in the solar cell field over the past several years, after Professor Henry Snaith鈥檚 group at Oxford 探花直播 found them to be remarkably efficient at converting light to electricity. In just two short years, perovskite-based solar cells have reached efficiencies of nearly 20%, a level which took conventional silicon-based solar cells 20 years.

Now, researchers from the 探花直播 of Cambridge, 探花直播 of Oxford and the Ludwig-Maximilians-Universit盲t in Munich have demonstrated a new application for perovskite materials, using them to make high-brightness LEDs. 探花直播results are published in the journal Nature Nanotechnology.

Perovskite is a general term used to describe a group of materials that have a distinctive crystal structure of cuboid and diamond shapes. They have long been of interest for their superconducting and ferroelectric properties. But in the past several years, their efficiency at converting light into electrical energy has opened up a wide range of potential applications.

探花直播perovskites that were used to make the LEDs are known as organometal halide perovskites, and contain a mixture of lead, carbon-based ions and halogen ions known as halides. These materials dissolve well in common solvents, and assemble to form perovskite crystals when dried, making them cheap and simple to make.

鈥淭hese organometal halide perovskites are remarkable semiconductors,鈥� said Zhi-Kuang Tan, a PhD student at the 探花直播 of Cambridge鈥檚 Cavendish Laboratory and the paper鈥檚 lead author. 鈥淲e have designed the diode structure to confine electrical charges into a very thin layer of the perovskite, which sets up conditions for the electron-hole capture process to produce light emission.鈥�

探花直播perovskite LEDs are made using a simple and scalable process in which a perovskite solution is prepared and spin-coated onto the substrate. This process does not require high temperature heating steps or a high vacuum, and is therefore cheap to manufacture in a large scale. In contrast, conventional methods for manufacturing LEDs make the cost prohibitive for many large-area display applications.

鈥� 探花直播big surprise to the semiconductor community is to find that such simple process methods still produce very clean semiconductor properties, without the need for the complex purification procedures required for traditional semiconductors such as silicon,鈥� said Professor Sir Richard Friend of the Cavendish Laboratory, who has led this programme in Cambridge.

鈥淚t鈥檚 remarkable that this material can be easily tuned to emit light in a variety of colours, which makes it extremely useful for colour displays, lighting and optical communication applications,鈥� said Tan. 鈥淭his technology could provide a lot of value to the ever growing flat-panel display industry.鈥�

探花直播team is now looking to increase the efficiency of the LEDs and to use them for diode lasers, which are used in a range of scientific, medical and industrial applications, such as materials processing and medical equipment. 探花直播first commercially-available LED based on perovskite could be available within five years.

Colourful LEDs made from a material known as perovskite could lead to LED displays which are both cheaper and easier to manufacture in future.

This technology could provide a lot of value to the ever growing flat-panel display industry

Zhi-Kuang Tan

LEDs made from perovskite

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