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KAIST, Making Pharmaceuticals with Light and Air… Solving a Long-Standing Challenge in Chemical Synthesis
<(From Left) Professor Sang Woo Han, Researcher Jin Wook Baek>
In chemical processes for producing pharmaceuticals, catalysts are the key to determine production speed and cost. However, until now, there has been a trade-off between “precise but disposable catalysts” and “reusable catalysts.” A KAIST research team has developed an eco-friendly catalytic technology that combines these two types, operating with light and air. This opens a pathway to producing pharmaceutical ingredients more cheaply and cleanly, with expected reductions in carbon emissions and environmental pollution.
KAIST (President Kwang Hyung Lee) announced on the 30th of March that a research team led by Professor Sang Woo Han of the Department of Chemistry has succeeded in combining two different types of catalysts into one system. One is a silver (Ag)-based catalyst that operates in a solid state, and the other is an organic photocatalyst, DDQ (a substance that triggers chemical reactions upon absorbing light), which operates in solution. By enabling these two catalysts to function together, the team made it possible to carry out previously difficult reactions more efficiently.
< Schematic diagram of the operation of a heterogeneous–homogeneous hybrid photocatalytic system >
Using this technology, the researchers successfully produced amines—key raw materials for pharmaceuticals—through an environmentally friendly process using light and air. This demonstrated that the desired substances can be synthesized without additional chemical reagents, proving the practicality of the technology.
Conventional organic photocatalysis required additional chemicals to reuse catalysts after reactions, or suffered from reduced efficiency due to slow reaction rates when using oxygen from air.
To address this, the research team proposed a method of reusing byproducts generated during the reaction. These byproducts restore the catalyst to a reusable state, while oxygen in the air helps sustain this cycle. In other words, instead of being used once and discarded, the catalyst regenerates itself and continues operating in a “cyclic system.”
As a result, they established a “cyclic catalytic system” that continues functioning without the need for additional chemical inputs. Notably, this system operates with light and air. Light activates the catalyst to initiate the reaction, while air restores the used catalyst to its active state. In essence, the catalyst continuously “recharges” and operates repeatedly. Since air leaves only water as a byproduct in this process, the environmental burden is significantly reduced.
In addition, to solve the issue of reduced performance when different catalysts interact, the team introduced lithium salt (LiClO₄). This substance helps regulate interactions between the two catalysts, significantly improving their stability and lifespan.
< A hybrid catalyst powered by light and air as energy sources >
Professor Sang Woo Han stated, “This research is the first to successfully integrate an inorganic photochemical loop system—where a metal-based catalyst reacts under light and returns to its original state—into the field of organic synthesis,” adding, “It represents an important advancement that combines the advantages of different catalytic systems to dramatically reduce the carbon footprint of the chemical industry.” He further noted, “It opens a new pathway for producing high-value compounds, such as pharmaceutical ingredients, in the most environmentally friendly way.”
This research was conducted with Jin Wook Baek of the KAIST Department of Chemistry as the first author, and the results were published on March 18 in the Journal of the American Chemical Society (JACS), a leading journal in chemistry.
※ Paper title: “Merger of heterogeneous and homogeneous photocatalysis for arene C–H Amination”
※ DOI: 10.1021/jacs.5c20824
This research was supported by the National Research Foundation of Korea’s Mid-career Researcher Program.
2026.03.30 View 440 -
Distinguished Professor Sang Yup Lee, Senior Vice President for Research, to Lead Industry-Academic-Research Cooperation in Synthetic Biology
< Sang Yup Lee, Senior Vice President for Research at KAIST (Inaugural Chairman of the Korea Synthetic Biology Association) >
KAIST announced on February 27th that Sang Yup Lee, Distinguished Professor of the Department of Chemical and Biomolecular Engineering and Senior Vice President for Research, has been appointed as the inaugural chairman of the Korea Synthetic Biology Association (KSBA). This appointment was officially ratified during the association's 5th regular general meeting held on the 23rd.
The KSBA is a specialized consultative body established to promote cooperation in policy, industry, and research within the field of synthetic biology. Based on a network spanning industry, academia, research institutes, and government, the association supports the creation of a synthetic biology ecosystem as a national strategic technology and strengthens industrial competitiveness. It has contributed to the expansion of the domestic synthetic biology foundation through multifaceted activities such as policy proposals, international cooperation, human resource development, and industrial vitalization.
Through this appointment of the inaugural chairman, the association has established a unified leadership system and is set to formalize the operational foundation in line with the enforcement of the "Synthetic Biology Promotion Act."
At the general meeting, the 2025 business performance report was presented, and agendas for the ratification of the next chairman and the appointment of executives were resolved. Officials from the Ministry of Science and ICT also attended, expressing expectations for the association’s political role and future direction.
During the meeting, the ratification of Chairman Sang Yup Lee, who was elected by the Board of Directors in accordance with the articles of incorporation, was finally approved. Chairman Sang Yup Lee is a world-leading researcher who has pioneered the fields of synthetic biology and biotechnology. As the Senior Vice President for Research at KAIST, Head of the Metabolic Engineering National Research Laboratory, and Director of both the BioProcess Engineering Research Center and the Center for Synthetic Biology, he has led research innovation and the expansion of global cooperation. With this ratification, the KSBA has officially launched an integrated leadership system encompassing the establishment of mid-to-long-term strategies, strengthening industry-research links, and expanding global networks.
< Group photo of the Korea Synthetic Biology Association General Meeting (Chairman Sang Yup Lee, 5th from the bottom left) >
Chairman Sang Yup Lee stated, "Synthetic biology is a key strategic technology that will determine national competitiveness. We will ensure close cooperation between industry, academia, research, and government so that the purpose of laws and systems can lead to practical innovation in research and industrial fields."
Furthermore, the Board of Directors approved the appointment of directors and external auditors to enhance the accountability and transparency of organizational management, including Steering Committee Secretary Lee Seung-koo (Korea Research Institute of Bioscience and Biotechnology), as well as Park Han-oh (Bioneer), Kim장성 (Korea Research Institute of Bioscience and Biotechnology), Kim Dong-myung (Chungnam National University), Oh Min-kyu (Korea University), Cho Byung-kwan (KAIST), Yoon Hye-sun (Hanyang University), and Lee Do-heon (KAIST).
At this general meeting, the major contents of the "Synthetic Biology Promotion Act," scheduled for enforcement on April 23, and the corresponding legislative notice of the enforcement decree were shared. Prior to the enforcement of the law, the Ministry of Science and ICT prepared an enforcement decree specifying delegated matters and has been conducting a legislative notice for 40 days starting February 23. The enforcement decree includes: ▲Clarification of procedures for establishing the Basic Plan for Synthetic Biology Promotion and annual implementation plans ▲Establishment of standards for designating and operating research hubs and biofoundries ▲Materialization of safety management systems and inspection procedures.
The KSBA plans to actively pursue implementation strategies for each division so that the legislative intent of the enforcement decree can be practically realized in industrial and research fields.
The Policy and System Division will strengthen its policy advisory function to ensure that field opinions are reflected in the process of establishing basic and annual implementation plans. It will also continue to present directions for synthetic biology development and social infrastructure construction strategies through the ‘KSBA Policy Insight 2026’ report.
The Convergence Division aims to advance research systems based on data, AI, and automation to simultaneously secure research reliability and efficiency. It will also support the strengthening of technology standardization and safety management capabilities through the publication of convergence technology trend reports and the operation of workshops.
The Technology and Industry Division plans to specify industry-research linkage models that meet the standards for designating and operating research infrastructure such as biofoundries. It will also expand corporate cooperation networks to ensure that the implementation of the system leads to technology commercialization and manufacturing innovation.
The Education and Network Division will prepare a competition (IDEA-B) to discover next-generation talent and strengthen safety and ethics education to increase the accountability and expertise of synthetic biology research. Additionally, it plans to expand international cooperation to ensure that domestic systems harmonize with global norms.
The KSBA plans to further enhance the stability of organizational operations through this general meeting and expand its role as a hub institution connecting policy, industry, and research. In particular, under the unified leadership centered on Chairman Sang Yup Lee, it intends to serve as a bridge for private-public cooperation so that the intent of the "Synthetic Biology Promotion Act" can be practically implemented in the field.
< KSBA Policy Insight 2026 Report of the Korea Synthetic Biology Association >
2026.02.27 View 1191 -
2026 KAIST Commencement: Shining Their Own Light on Their Respective Stages
KAIST (President Kwang Hyung Lee) announced that it held its 2026 Commencement Ceremony at 2 p.m. on February 20th at the Sports Complex on its Main Campus in Daejeon.
At this year’s ceremony, a total of 3,334 graduates received degrees, including 817 doctoral, 1,792 master’s, and 725 bachelor’s degrees. Since its founding in 1971, KAIST has now produced a total of 84,490 highly qualified science and technology professionals, including 18,130 Ph.D. recipients, 43,358 master’s graduates, and 23,002 bachelor’s graduates.
KAIST selected three representative graduates who embody the university’s vision of talent. They are Seunghyun Ryu (Department of Bio and Brain Engineering), the doctoral representative known as the “pianist neuroscientist” for his interdisciplinary research bridging brain science and piano performance; Jeanne Choi (School of Computing), the master’s representative who has pursued warm and inclusive technologies for socially vulnerable groups under the themes of accessibility and inclusion; and Mert Yakup Baykan (Department of Aerospace Engineering), the bachelor’s representative from Cyprus holding Turkish nationality, who became the first international recipient of the KAIST Presidential Scholarship.
Seunghyun Ryu, selected as both the doctoral representative and one of the notable graduates, spent 14 years at KAIST completing his undergraduate through doctoral studies while balancing research and music. He organized and managed performances through the campus piano club “PIAST,” expanding artistic activities within the campus community. His research explored the inverse relationship between Alzheimer’s disease and cancer, revealing how disease-related proteins and anticancer drugs act in neurons and offering new perspectives on inter-disease connections.
Jeanne Choi, the master’s representative and another notable graduate, presented research at AAATE 2023 in Paris, analyzing the experiences of visually impaired users engaging with the metaverse and artificial intelligence. Accompanying a visually impaired professor during the conference, Choi gained firsthand insight into mobility and safety challenges, which further expanded the scope of her research. Choi has since continued field-based research, including serving as a teaching assistant at AI and coding camps for visually impaired youth, and plans to pursue a doctoral degree while continuing research for socially vulnerable communities.
Bachelor’s representative Mert Yakup Baykan actively participated in research during his undergraduate studies, publishing four SCI-indexed papers and delivering five conference presentations. He was also selected as a visiting student researcher at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, gaining international collaborative research experience. As the first international KAIST Presidential Scholar, he plans to pursue a Ph.D. at Stanford University and grow into a leading researcher in space propulsion and combustion.
Awards for outstanding graduates were also presented. Seohyeon Kang (B.S., Brain and Cognitive Sciences) received the Minister of Science and ICT Award (Deputy Prime Minister’s Award). The Chairman of the Board Award was presented to Thai international student Punn Lertjaturaphat (B.S., Industrial Design). The President’s Award went to Kyeongmin Yeo (B.S., School of Computing), while the Alumni Association President’s Award and the KAIST Development Foundation Chairman’s Award were presented to Wonwoo Yoo (B.S., Aerospace Engineering) and Sungbeen Park (B.S., Nuclear and Quantum Engineering), respectively. Hyuk-chae Koo, 1st Vice Minister of Science and ICT, presented the awards on behalf of the Deputy Prime Minister and Minister of Science and ICT.
Seohyeon Kang developed a technology to measure key proteins related to Parkinson’s disease without surgery or tissue damage, opening new possibilities in brain disease research, and was recognized as a model graduate who combined academic excellence with community service. Punn Lertjaturaphat gained recognition at prestigious international conferences such as ACM CHI and co-founded a startup addressing rural elderly care issues, demonstrating creativity in solving social problems through technology and design.
Kyeongmin Yeo published six research papers at leading AI conferences including NeurIPS, ICLR, and CVPR, proposing new theoretical approaches to image generation and demonstrating outstanding academic achievement as a young researcher.
Wonwoo Yoo led the overseas volunteer corps and served as student representative, combining leadership with academic excellence, including winning a grand prize in a rocket launch competition. Sungbeen Park proposed a next-generation beta battery concept, linking it to patents and entrepreneurship, while contributing to public communication and outreach in nuclear technology as student council president and university ambassador.
Commencement addresses were delivered by Dongjae Kang (B.S., Industrial and Systems Engineering) and Gul Osman (Ph.D., Mechanical Engineering), an international student from Türkiye. Kang reflected on how he learned science not merely as an avenue for problem-solving but as a process for exploring the deeper meaning behind phenomena, pledging to remain attentive to unseen challenges faced by others. Osman shared his journey of nurturing his passion for science while working in a factory under difficult economic circumstances, emphasizing that opportunities open to those who persist without giving up. He began his academic journey in Korea through the Korean Government Scholarship Program.
This year, KAIST also spotlighted three notable graduates who forged their own paths encompassing research, the arts, and social value: Seunghyun Ryu, Jeanne Choi, and Daehui Kim (B.S., Civil and Environmental Engineering). Kim led campus environmental organizations and community-based environmental campaigns, earning an Environmental Contribution Award. He plans to pursue a master’s degree focusing on carbon dioxide geological storage research. He also performs as the vocalist of the KAIST metal band “INFINITE,” continuing to balance music and research.
During the ceremony, an Honorary Doctorate in Business Administration was conferred upon uey-Yu Wang, Executive Management Committee Member of Formosa Group and Chairman of Formosa Biomedical Technology Corporation.
President Kwang Hyung Lee encouraged the graduates, saying, “Cherish your dreams, seize opportunities, do not fear failure, and continue to challenge yourselves. I hope you will shine in your own way on your own stage and contribute to society as proud members of the KAIST community.”
2026.02.21 View 2353 -
KAIST Overcomes Limitations of Existing Image Sensors… Clear Colors Even Under Oblique Light
<(From Left) Ph.D candidate Chanhyung Park from Electrical Engineering, Jaehyun Jeon from Department of Physics, Professor Min Seok Jang from Electrical Engineering>
Smartphone cameras are becoming smaller, yet photos are becoming sharper. Korean researchers have elevated the limits of next-generation smartphone cameras by developing a new image sensor technology that can accurately represent colors regardless of the angle at which light enters. The team achieved this by utilizing a “metamaterial” that designs the movement of light through structures too small to be seen with the naked eye.
KAIST (President Kwang Hyung Lee) announced on the 12th of February that a research team led by Professor Min Seok Jang of the School of Electrical Engineering, in collaboration with Professor Haejun Chung’s team at Hanyang, has developed a metamaterial-based technology for image sensors that can stably separate colors even when the angle of light incidence varies.
Conventional smartphone cameras capture images by concentrating light into a small lens. However, as camera pixels become extremely small, lenses alone struggle to gather sufficient light. To address this, the Nanophotonic Color Router was introduced. Instead of concentrating light through a lens, this technology uses microscopic structures invisible to the eye to precisely separate incoming light by color. By designing the pathways through which light travels, this metamaterial-based structure accurately divides light into red (R), green (G), and blue (B).
Samsung Electronics has already demonstrated the commercialization potential of this technology by applying it to actual image sensors under the name “Nano Prism.” Theoretically, stacking multiple layers of extremely fine nanostructures enables greater light collection and more accurate color separation.
<Nanophotonic color router technology that works reliably even under oblique incidence conditions (AI-generated image)>
However, existing Nanophotonic Color Routers had limitations. While they functioned well when light entered vertically, their performance deteriorated significantly—or colors mixed—when light entered at an angle, as is common in smartphone cameras. This issue, known as the “oblique incidence problem,” has been considered a critical challenge that must be resolved for real-world product applications.
The research team first investigated the root cause of this issue. They found that previous designs were overly optimized for vertically incident light, causing performance to drop sharply even with slight changes in the angle of incidence. Since smartphone cameras receive light from various angles, maintaining performance under angular variation is essential.
Instead of manually designing the structure, the team adopted an “inverse design” approach, which allows the computer to autonomously determine the optimal structure. Through this method, they derived a color router design capable of stable color separation even when the angle of incoming light changes.
As a result, whereas previous structures nearly failed when light was tilted by about 12 degrees, the newly designed structure maintained approximately 78% optical efficiency within a ±12-degree range, demonstrating stable color separation performance. In other words, the technology reaches a level suitable for practical smartphone usage environments.
<Nanophotonic color router robust to oblique incidence>
The team further analyzed performance variations by considering factors such as the number of metamaterial layers, design conditions, and potential fabrication errors. They also systematically defined the limits of robustness against changes in the angle of incidence. This study is particularly meaningful in that it presents design criteria for color routers that reflect realistic image sensor environments.
Professor Min Seok Jang of KAIST stated, “This research is significant in that it systematically analyzes the oblique incidence problem, which has hindered the commercialization of color router technology, and proposes a clear solution direction,” adding, “The proposed design methodology can be extended beyond color routers to a wide range of metamaterial-based nanophotonic devices.”
In this study, KAIST undergraduate student Jaehyun Jeon and doctoral candidate Chanhyung Park participated as co-first authors. The research findings were published on January 27 in the international journal Advanced Optical Materials.
※ Paper title: “Inverse Design of Nanophotonic Color Router Robust to Oblique Incidence”
DOI: https://doi.org/10.1002/adom.202501697※ Authors: Jaehyun Jeon (KAIST, first author), Chanhyung Park (KAIST, first author), Doyoung Heo (KAIST), Haejun Chung (Hanyang University), Min Seok Jang (KAIST, corresponding author)
This research was supported by the Ministry of Trade, Industry & Energy (Korea Institute for Advancement of Technology, Korea Semiconductor Research Consortium) under the project “Design Technology of Meta-Optical Structures for Next-Generation Sensors,” by the Ministry of Science and ICT (National Research Foundation of Korea) under the projects “Development of Full-Color Micro LED Devices and Panels Based on Beam-Steerable High-Color-Purity Meta Color Conversion Layers” and “Development of a Real-Time Zero-Energy Argos-Eye Metasurface Network Computing with All Properties of Light,” and by the Ministry of Culture, Sports and Tourism (Korea Creative Content Agency) under the project “International Joint Research for Next-Generation Copyright Protection and Secure Content Distribution Technologies.”
2026.02.19 View 1234 -
Seeing Black Holes More Clearly with Laser Light
<(From Left) Researcher Junyong Choi, Researcher Woosong Jeong, Professor Jungwon Kim, Researcher Jihoon Baek >
Radio telescopes are instruments that capture faint radio signals from space and convert them into images of celestial bodies. To observe distant black holes clearly, multiple radio telescopes must capture cosmic signals at exactly the same time, acting as a single unit. Research teams at KAIST have developedr a new reference signal technology that uses laser light to precisely synchronize the observation timing and phase of these telescopes.
KAIST announced on January 15th that a research team led by Professor Jungwon Kim from the Department of Mechanical Engineering—in collaboration with the Korea Astronomy and Space Science Institute, the Korea Research Institute of Standards and Science, and the Max Planck Institute for Radio Astronomy (MPIfR) in Germany—has implemented a technology that directly applies optical frequency comb lasers to radio telescope receivers.
While a typical laser emits only one color (frequency), an optical frequency comb laser emits tens of thousands of extremely accurate colors arranged at regular intervals. This appearance resembles the teeth of a comb, hence the name "frequency comb." Since the frequency of each individual "tooth" is known exactly and the intervals can be precision-tuned to the level of an atomic clock, scientists refer to it as an "ultra-precision ruler made of light."
The core of Very Long Baseline Interferometry (VLBI), a technique where multiple radio telescopes observe simultaneously, is aligning the phases of the radio signals received by each telescope as if aligning them to a single precise ruler. However, existing electronic reference signal methods faced limitations; as observation frequencies increased, precise phase calibration is becoming more difficult.
In response, the KAIST research team developed a method to deliver the optical frequency comb laser directly into the radio telescope, based on the idea of "improving the fundamental precision of phase alignment by utilizing light (lasers) from the signal generation stage." Through this, they successfully solved the problems of reference signal generation and phase calibration simultaneously within a single optical system.
If the conventional method was like using a "ruler that makes phase alignment difficult" at higher frequencies, this new technology can be compared to setting a standard with an "ultra-precision ruler that fixes the phase with extremely stable light." As a result, they have laid the foundation for distant radio telescopes to interoperate as elaborately as one giant telescope.
This technology was verified through test observations at the Korea VLBI Network (KVN) Yonsei Radio Telescope. The research team succeeded in detecting stable interference patterns (fringes) between radio telescopes and proved through actual observation that precise phase calibration is possible. Recently, this system was also installed at the KVN SNU Pyeongchang Radio Telescope, leading to expanded experiments using multiple observation sites simultaneously.
The team expects that this will not only allow for clearer imaging of black holes but also drastically reduce phase delay errors between instruments—a long-standing issue in VLBI observations.
The applications of this technology are not limited to astronomical observations. The team anticipates that it can be expanded to various advanced fields requiring precise space-time measurements, such as▲ Intercontinental ultra-precision clock comparison ▲Space geodesy ▲Deep-space probe tracking
< Illustration of the system principle (Image generated by AI) >
Professor Jungwon Kim of KAIST stated, "This research is a case where the limits of existing electronic signal generation technology were overcome by directly applying optical frequency comb lasers to radio telescopes. It will significantly contribute to improving the precision of next-generation black hole observations and advancing the fields of frequency metrology and time standards."
Dr. Minji Hyun (currently at KRISS) and Dr. Changmin Ahn from KAIST participated as co-first authors. The research findings were published on January 4th in the international academic journal Light: Science & Applications.
Paper Title: Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration
DOI: 10.1038/s41377-025-02056-w
Lead Authors: Dr. Minji Hyun (KAIST, currently KRISS), Dr. Changmin Ahn (KAIST), Jungwon Kim (KAIST)
This research was conducted with support from the National Research Council of Science & Technology (NST) Creative Alliance Project(CAP), the National Research Foundation of Korea (NRF), and the Institute of Information & Communications Technology Planning & Evaluation (IITP).
2026.01.15 View 2016 -
Breaking the 1% Barrier, KAIST Boosts Brightness of Eco-Friendly Ultra-Small Semiconductors by 18-Fold
<(Front rwo, from left) KAIST co-first author Changhyun Joo, co-first author Seongbeom Yeon, (Back row, from left) Jaeyoung Ha, Professor Himchan Cho, Jaedong Jang>
Light-emitting semiconductors are used throughout everyday life in TVs, smartphones, and lighting. However, many technical barriers remain in developing environmentally friendly semiconductor materials. In particular, nanoscale semiconductors that are tens of thousands of times smaller than the width of a human hair (about 100,000 nanometers) are theoretically capable of emitting bright light, yet in practice have suffered from extremely weak emission. KAIST researchers have now developed a new surface-control technology that overcomes this limitation.
KAIST (President Kwang Hyung Lee) announced on the 14th of January that a research team led by Professor Himchan Cho of the Department of Materials Science and Engineering has developed a fundamental technology to control, at the atomic level, the surface of indium phosphide (InP)* magic-sized clusters (MSCs)—nanoscale semiconductor particles regarded as next-generation eco-friendly semiconductor materials.* Indium phosphide (InP): a compound semiconductor made of indium (In) and phosphorus (P), considered an environmentally friendly alternative that does not use hazardous elements such as cadmium
The material studied by the team is known as a magic-sized cluster, an ultrasmall semiconductor particle composed of only several tens of atoms. Because all particles have identical size and structure, these materials are theoretically capable of emitting extremely sharp and pure light. However, due to their extremely small size of just 1–2 nanometers, even minute surface defects cause most of the emitted light to be lost. As a result, luminescence efficiency has remained below 1% to date.
Previously, this issue was addressed by etching the surface with strong chemicals such as hydrofluoric acid (HF). However, the overly aggressive reactions often damaged the semiconductor itself.
Professor Cho’s team adopted a different approach. Instead of removing the surface all at once, they devised a precision etching strategy that allows chemical reactions to proceed in a highly controlled, incremental manner. This enabled selective removal of only the defect sites that hindered light emission, while preserving the overall structure of the semiconductor. During this defect-removal process, fluorine generated by the reaction combined with zinc species in the solution to form zinc chloride, which in turn stabilized and passivated the exposed nanocrystal surface.
< Schematic illustration of overcoming emission efficiency limits via atomic-scale precision control >
As a result, the research team increased the luminescence efficiency of the semiconductor from below 1% to 18.1%. This represents the highest reported performance to date among indium phosphide–based ultrasmall nanosemiconductors, corresponding to an 18-fold increase in brightness.
This study is particularly significant in that it demonstrates, for the first time, that the surfaces of ultrasmall semiconductors—previously considered nearly impossible to control—can be precisely engineered at the atomic level. The technology is expected to find applications not only in next-generation displays, but also in advanced fields such as quantum communication and infrared sensing.
< Eco-friendly Ultra-compact Semiconductor Chemical Reaction (AI-generated image) >
Professor Himchan Cho explained, “This work is not simply about making brighter semiconductors, but about demonstrating how critical atomic-level surface control is for achieving desired performance.”
This research was carried out with Changhyun Joo, a doctoral student, and Seongbeom Yeon, a combined master’s-doctoral student in the Department of Materials Science and Engineering at KAIST, serving as co–first authors. Professor Himchan Cho and Professor Ivan Infante of the Basque Center for Materials, Applications, and Nanostructures (BCMaterials, Spain) participated as co-corresponding authors. The study was published online on December 16 in the Journal of the American Chemical Society (JACS), one of the most prestigious journals in chemistry.
※ Paper title: “Overcoming the Luminescence Efficiency Limitations of InP Magic-Sized Clusters,” DOI: 10.1021/jacs.5c13963
This research was supported by the National Research Foundation of Korea through the Nano Materials Technology Development Program, the Next-Generation Intelligent Semiconductor Technology Development Program, the Quantum Information Science Human Infrastructure Program, and by the Korea Basic Science Institute through its Infrastructure Support Program for Early-Career Researchers.
2026.01.14 View 1606 -
KAIST Develops OLED Technology with Double the Screen Brightness
<(From Left) Ph.D candidate Minjae Kim, Professor Seunghyup Yoo, Dr. Junho Kim>
Organic light-emitting diodes (OLEDs) are widely used in smartphones and TVs thanks to their excellent color reproduction and thin, flexible planar structure. However, internal light loss has limited further improvements in brightness. KAIST researchers have now developed a technology that more than doubles OLED light-emission efficiency while maintaining the flat structure that is a key advantage of OLED displays.
KAIST (President Kwang Hyung Lee) announced on the 11th of January that a research team led by Professor Seunghyup Yoo of the School of Electrical Engineering has developed a new near-planar light outcoupling structure* and an OLED design method that can significantly reduce light loss inside OLED devices.* Near-planar light outcoupling structure: a thin structure that keeps the OLED surface almost flat while extracting more of the light generated inside to the outside
OLEDs are composed of multiple layers of ultrathin organic films stacked on top of one another. As light passes through these layers, it is repeatedly reflected or absorbed, often causing more than 80% of the light generated inside the OLED to be lost as heat before it can escape.
To address this issue, light outcoupling structures such as hemispherical lenses or microlens arrays (MLAs) have been used to extract light from OLEDs. However, hemispherical lenses protrude significantly, making it difficult to maintain a flat form factor, while MLAs must cover much larger area than individual pixel sizes to achieve sufficient light extraction. This creates limitations in achieving high efficiency without interference between neighboring pixels.
To increase OLED brightness while preserving a planar structure, the research team proposed a new OLED design strategy that maximizes light extraction within the size of each individual pixel.
Unlike conventional designs that assume OLEDs extend infinitely, this approach takes into account the finite pixel sizes actually used in real displays. As a result, more light can be emitted externally even from pixels of the same size.
In addition, the team developed a new near-planar light outcoupling structure that helps light emerge efficiently in the forward direction without being spread too widely. This structure is very thin—comparable in thickness to existing microlens arrays—yet achieves light extraction efficiency close to that of hemispherical lenses of the same lateral dimension. As a result, it hardly undermines the flat form factors of OLEDs and can be readily applied to flexible OLED displays.
By combining the new OLED design with the near-planar light outcoupling structure, the researchers successfully achieved more than a twofold improvement in light-emission efficiency even in small pixels.
< Quasi-Planar Light Extraction OLED Technology >
This technology enables brighter displays using the same power while maintaining OLED’s flat structure, and is expected to extend battery life and reduce heat generation in mobile devices such as smartphones and tablets. Improvements in display lifespan are also anticipated.
MinJae Kim, the first author of the study, noted, “A small idea that came up during class was developed into real research results through the KAIST Undergraduate Research Program (URP).”
Professor Seunghyup Yoo stated, “Although many light outcoupling structures have been proposed, most were designed for large-area lighting applications, and many were difficult to apply effectively to displays composed of numerous small pixels,” adding, “The near-planar light outcoupling structure proposed in this work was designed with constraints on the size of the light source within each pixel, reducing optical interference between adjacent pixels while maximizing efficiency.” He further emphasized that the approach can be applied not only to OLEDs but also to next-generation display technologies based on materials such as perovskites and quantum dots.
< Schematic Overview and Application Examples of the Proposed Light Extraction Structure >
This research, with MinJae Kim (Department of Materials Science and Engineering, KAIST; currently a Ph.D. student in Materials Science and Engineering at Stanford University) and Junho Kim (School of Electrical Engineering, KAIST; currently a postdoctoral researcher at the University of Cologne, Germany) as co–first authors, was published online on December 29, 2025, in Nature Communications.
※ Paper title: “Near-planar light outcoupling structures with finite lateral dimensions for ultra-efficient and optical crosstalk-free OLED displays” DOI: 10.1038/s41467-025-66538-6
This research was supported by the KAIST Undergraduate Research Program (URP), the Mid-Career Researcher Program and the Future Display Strategic Research Lab Program of the National Research Foundation (NRF) of Korea, the Human Resource Development Program of the Korea Institute for Advancement of Technology (KIAT), and the Korea Planning & Evaluation Institute of Industrial Technology (KEIT).
2026.01.12 View 2106 -
First Elucidation of Spontaneous Emission and Excitation in Photonic Time Crystals
< (From left) Professor Bumki Min, Ph.D. Candidate Kyungmin Lee >
A groundbreaking discovery reveals that spontaneous emission, a key phenomenon in the interaction between light and atoms, manifests in a new form within a Photonic Time Crystal (PTC). This research, led by a KAIST team, not only overturns existing theory but further predicts a novel phenomenon: spontaneous emission excitation.
Professor Bumki Min's research team from the KAIST Department of Physics, in collaboration with Professor Jonghwa Shin of the Department of Materials Science and Engineering, Professor Wonju Jeon of the Department of Mechanical Engineering, Professor Gil Young Cho of the Department of Physics, and researchers from IBS, UC Berkeley, and the Hong Kong University of Science and Technology, announced that they have proven that the spontaneous emission decay rate in a Photonic Time Crystal is, on the contrary, enhanced rather than being "extinguished," as suggested by a paper published in Science in 2022. Furthermore, they predicted a new process—spontaneous emission excitation—where an atom transitions from its ground state to an excited state while simultaneously emitting a photon.
< Spontaneous emission decay rate (left) and spontaneous emission excitation rate (right) when a quantum emitter (or atom) is placed in an environment that changes very rapidly and periodically in time >
Spontaneous emission is the process by which an atom intrinsically emits a photon and is fundamental to quantum optics and photonic device research. Until now, control over spontaneous emission has been achieved by designing spatial structures like resonators or photonic crystals. However, the advent of Photonic Time Crystals, which periodically modulate the refractive index of a medium over time, has drawn attention to the potential for control along the time axis.
Previous theory predicted that the spontaneous emission decay rate in a Photonic Time Crystal would completely vanish at a specific frequency. In contrast, this study is the first to prove that the decay rate is significantly enhanced. This is attributed to the non-orthogonal mode effect, highlighting the importance of research into non-Hermitian optics.
The research team also predicted and reported a new process, 'spontaneous emission excitation,' where an atom gains energy and transitions from its ground state to an excited state while simultaneously emitting a photon. This is a non-equilibrium process made possible by the time-crystal medium supplying external energy, representing a new light-matter interaction phenomenon that cannot be explained by conventional equilibrium optics.
The findings fundamentally shift the paradigm of spontaneous emission research and hold promise for broad applications in fields such as quantum light source design and non-equilibrium quantum optics.
Professor Bumki Min stated, "This achievement re-establishes the fundamental theory describing spontaneous emission in a rapidly time-varying environment. The enhancement of spontaneous emission decay and the 'spontaneous emission excitation' phenomenon have the potential to change the paradigm of light-matter interaction research."
Ph.D. candidate Kyungmin Lee participated as the first author of this research. The results were published online in the international academic journal Physical Review Letters on September 23, 2025, simultaneously highlighted on Physics.org, and selected as an Editors' Suggestion paper. The research was supported by the National Research Foundation of Korea and the Samsung Science and Technology Foundation.
Note: The paper is titled “Spontaneous emission decay and excitation in photonic time crystals.”
2025.10.01 View 2315 -
KAIST develops world’s most sensitive light-powered photodetector—20 times more sensitive, operating without electricity
<(From left) Ph.D candidate Jaeha Hwang, Ph.D candidate Jungi Song ,Professor Kayoung Lee from Electrical Engineering>
Silicon semiconductors used in existing photodetectors have low light responsivity, and the two-dimensional semiconductor MoS₂ (molybdenum disulfide) is so thin that doping processes to control its electrical properties are difficult, limiting the realization of high-performance photodetectors. The KAIST research team has overcome this technical limitation and developed the world’s highest-performing self-powered photodetector, which operates without electricity in environments with a light source. This paves the way for an era where precise sensing is possible without batteries in wearable devices, biosignal monitoring, IoT devices, autonomous vehicles, and robots, as long as a light source is present.
KAIST (President Kwang Hyung Lee) announced on the 14th of August that Professor Kayoung Lee’s research team from the School of Electrical Engineering has developed a self-powered photodetector that operates without external power supply. This sensor demonstrated a sensitivity up to 20 times higher than existing products, marking the highest performance level among comparable technologies reported to date.
Professor Kayoung Lee’s team fabricated a “PN junction structure” photodetector capable of generating electrical signals on its own in environments with light, even without an electrical energy supply, by introducing a “van der Waals bottom electrode” that makes semiconductors extremely sensitive to electrical signals without doping.
First, a “PN junction” is a structure formed by joining p-type (hole-rich) and n-type (electron-rich) materials in a semiconductor. This structure causes current to flow in one direction when exposed to light, making it a key component in photodetectors and solar cells.
Normally, to create a proper PN junction, a process called “doping” is required, which involves deliberately introducing impurities into the semiconductor to alter its electrical properties. However, two-dimensional semiconductors such as MoS₂ are only a few atoms thick, so doping in the conventional way can damage the structure or reduce performance, making it difficult to create an ideal PN junction.
To overcome these limitations and maximize device performance, the research team designed a new device structure incorporating two key technologies: the “van der Waals electrode” and the “partial gate.”
The “partial gate” structure applies an electrical signal only to part of the two-dimensional semiconductor, controlling one side to behave like p-type and the other like n-type. This allows the device to function electrically like a PN junction without doping.
Furthermore, considering that conventional metal electrodes can chemically bond strongly to the semiconductor and damage its lattice structure, the “van der Waals bottom electrode” was attached gently using van der Waals forces. This preserved the original structure of the two-dimensional semiconductor while ensuring effective electrical signal transfer.
This innovative approach secured both structural stability and electrical performance, enabling the realization of a PN junction in thin two-dimensional semiconductors without damaging their structure.
Thanks to this innovation, the team succeeded in implementing a high-performance PN junction without doping. The device can generate electrical signals with extreme sensitivity as long as there is light, even without an external power source. Its light detection sensitivity (responsivity) exceeds 21 A/W, more than 20 times higher than powered conventional sensors, 10 times higher than silicon-based self-powered sensors, and over twice as high as existing MoS₂ sensors. This level of sensitivity means it can be applied immediately to high-precision sensors capable of detecting biosignals or operating in dark environments.
Professor Kayoung Lee stated that they “have achieved a level of sensitivity unimaginable in silicon sensors, and although two-dimensional semiconductors are too thin for conventional doping processes, [they] succeeded in implementing a PN junction that controls electrical flow without doping.” She added, “This technology can be used not only in sensors but also in key components that control electricity inside smartphones and electronic devices, providing a foundation for miniaturization and self-powered operation of next-generation electronics.”
Jaeha Hwang, Jungi Song, Experimnet in Porgress>
This research, with doctoral students Jaeha Hwang and Jungi Song as co-first authors, was published online on July 26 in Advanced Functional Materials (IF 19), a leading journal in materials science.
※ Paper title: Gated PN Junction in Ambipolar MoS₂ for Superior Self-Powered Photodetection
※ DOI: https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202510113
Meanwhile, this work was supported by the National Research Foundation of Korea, the Korea Basic Science Institute, Samsung Electronics, and the Korea Institute for Advancement of Technology.
2025.08.16 View 3611 -
KAIST Develops World’s First Wireless OLED Contact Lens for Retinal Diagnostics
<ID-style photograph against a laboratory background featuring an OLED contact lens sample (center), flanked by the principal authors (left: Professor Seunghyup Yoo ; right: Dr. Jee Hoon Sim). Above them (from top to bottom) are: Professor Se Joon Woo, Professor Sei Kwang Hahn, Dr. Su-Bon Kim, and Dr. Hyeonwook Chae>
Electroretinography (ERG) is an ophthalmic diagnostic method used to determine whether the retina is functioning normally. It is widely employed for diagnosing hereditary retinal diseases or assessing retinal function decline.
A team of Korean researchers has developed a next-generation wireless ophthalmic diagnostic technology that replaces the existing stationary, darkroom-based retinal testing method by incorporating an “ultrathin OLED” into a contact lens. This breakthrough is expected to have applications in diverse fields such as myopia treatment, ocular biosignal analysis, augmented-reality (AR) visual information delivery, and light-based neurostimulation.
On the 12th, KAIST (President Kwang Hyung Lee) announced that a research team led by Professor Seunghyup Yoo from the School of Electrical Engineering, in collaboration with Professor Se Joon Woo of Seoul National University Bundang Hospital (Director Jeong-Han Song), Professor Sei Kwang Hahn of POSTECH (President Sung-Keun Kim) and CEO of PHI Biomed Co., and the Electronics and Telecommunications Research Institute (ETRI, President Seungchan Bang) under the National Research Council of Science & Technology (NST, Chairman Youngshik Kim), has developed the world’s first wireless contact lens-based wearable retinal diagnostic platform using organic light-emitting diodes (OLEDs).
<Figure 1. Schematic and photograph of the wireless OLED contact lens>
This technology enables ERG simply by wearing the lens, eliminating the need for large specialized light sources and dramatically simplifying the conventional, complex ophthalmic diagnostic environment.
Traditionally, ERG requires the use of a stationary Ganzfeld device in a dark room, where patients must keep their eyes open and remain still during the test. This setup imposes spatial constraints and can lead to patient fatigue and compliances challenges.
To overcome these limitations, the joint research team integrated an ultrathin flexible OLED —approximately 12.5 μm thick, or 6–8 times thinner than a human hair— into a contact lens electrode for ERG. They also equipped it with a wireless power receiving antenna and a control chip, completing a system capable of independent operation.
For power transmission, the team adopted a wireless power transfer method using a 433 MHz resonant frequency suitable for stable wireless communication. This was also demonstrated in the form of a wireless controller embedded in a sleep mask, which can be linked to a smartphone —further enhancing practical usability.
<Figure 2. Schematic of the electroretinography (ERG) testing system using a wireless OLED contact lens and an example of an actual test in progress>
While most smart contact lens–type light sources developed for ocular illumination have used inorganic LEDs, these rigid devices emit light almost from a single point, which can lead to excessive heat accumulation and thus usable light intensity. In contrast, OLEDs are areal light sources and were shown to induce retinal responses even under low luminance conditions. In this study, under a relatively low luminance* of 126 nits, the OLED contact lens successfully induced stable ERG signals, producing diagnostic results equivalent to those obtained with existing commercial light sources.
*Luminance: A value indicating how brightly a surface or screen emits light; for reference, the luminance of a smartphone screen is about 300–600 nits (can exceed 1000 nits at maximum).
Animal tests confirmed that the surface temperature of a rabbit’s eye wearing the OLED contact lens remained below 27°C, avoiding corneal heat damage, and that the light-emitting performance was maintained even in humid environments—demonstrating its effectiveness and safety as an ERG diagnostic tool in real clinical settings.
Professor Seunghyup Yoo stated that “integrating the flexibility and diffusive light characteristics of ultrathin OLEDs into a contact lens is a world-first attempt,” and that “this research can help expand smart contact lens technology into on-eye optical diagnostic and phototherapeutic platforms, contributing to the advancement of digital healthcare technology.”
< Wireless operation of the OLED contact lens >
Jee Hoon Sim, Hyeonwook Chae, and Su-Bon Kim, PhD researchers at KAIST, played a key role as co-first authors alongside Dr. Sangbaie Shin of PHI Biomed Co.. Corresponding authors are Professor Seunghyup Yoo (School of Electrical Engineering, KAIST), Professor Sei Kwang Hahn (Department of Materials Science and Engineering, POSTECH), and Professor Se Joon Woo (Seoul National University Bundang Hospital). The results were published online in the internationally renowned journal ACS Nano on May 1st.
● Paper title: Wireless Organic Light-Emitting Diode Contact Lenses for On-Eye Wearable Light Sources and Their Application to Personalized Health Monitoring
● DOI: https://doi.org/10.1021/acsnano.4c18563
● Related video clip: http://bit.ly/3UGg6R8
< Close-up of the OLED contact lens sample >
2025.08.12 View 4937 -
Is 24-hour health monitoring possible with ambient light energy?
<(From left) Ph.D candidate Youngmin Sim, Ph.D candidate Do Yun Park, Dr. Chanho Park, Professor Kyeongha Kwon>
Miniaturization and weight reduction of medical wearable devices for continuous health monitoring such as heart rate, blood oxygen saturation, and sweat component analysis remain major challenges. In particular, optical sensors consume a significant amount of power for LED operation and wireless transmission, requiring heavy and bulky batteries. To overcome these limitations, KAIST researchers have developed a next-generation wearable platform that enables 24-hour continuous measurement by using ambient light as an energy source and optimizing power management according to the power environment.
KAIST (President Kwang Hyung Lee) announced on the 30th that Professor Kyeongha Kwon's team from the School of Electrical Engineering, in collaboration with Dr. Chanho Park’s team at Northwestern University in the U.S., has developed an adaptive wireless wearable platform that reduces battery load by utilizing ambient light.
To address the battery issue of medical wearable devices, Professor Kyeongha Kwon’s research team developed an innovative platform that utilizes ambient natural light as an energy source. This platform integrates three complementary light energy technologies.
<Figure1.The wireless wearable platform minimizes the energy required for light sources through i) Photometric system that directly utilizes ambient light passing through windows for measurements, ii) Photovoltaic system that receives power from high-efficiency photovoltaic cells and wireless power receiver coils, and iii) Photoluminescent system that stores light using photoluminescent materials and emits light in dark conditions to support the two aforementioned systems. In-sensor computing minimizes power consumption by wirelessly transmitting only essential data. The adaptive power management system efficiently manages power by automatically selecting the optimal mode among 11 different power modes through a power selector based on the power supply level from the photovoltaic system and battery charge status.>
The first core technology, the Photometric Method, is a technique that adaptively adjusts LED brightness depending on the intensity of the ambient light source. By combining ambient natural light with LED light to maintain a constant total illumination level, it automatically dims the LED when natural light is strong and brightens it when natural light is weak.
Whereas conventional sensors had to keep the LED on at a fixed brightness regardless of the environment, this technology optimizes LED power in real time according to the surrounding environment. Experimental results showed that it reduced power consumption by as much as 86.22% under sufficient lighting conditions.
The second is the Photovoltaic Method using high-efficiency multijunction solar cells. This goes beyond simple solar power generation to convert light in both indoor and outdoor environments into electricity. In particular, the adaptive power management system automatically switches among 11 different power configurations based on ambient conditions and battery status to achieve optimal energy efficiency.
The third innovative technology is the Photoluminescent Method. By mixing strontium aluminate microparticles* into the sensor’s silicone encapsulation structure, light from the surroundings is absorbed and stored during the day and slowly released in the dark. As a result, after being exposed to 500W/m² of sunlight for 10 minutes, continuous measurement is possible for 2.5 minutes even in complete darkness.
*Strontium aluminate microparticles: A photoluminescent material used in glow-in-the-dark paint or safety signs, which absorbs light and emits it in the dark for an extended time.
These three technologies work complementarily—during bright conditions, the first and second methods are active, and in dark conditions, the third method provides additional support—enabling 24-hour continuous operation.
The research team applied this platform to various medical sensors to verify its practicality. The photoplethysmography sensor monitors heart rate and blood oxygen saturation in real time, allowing early detection of cardiovascular diseases. The blue light dosimeter accurately measures blue light, which causes skin aging and damage, and provides personalized skin protection guidance. The sweat analysis sensor uses microfluidic technology to simultaneously analyze salt, glucose, and pH in sweat, enabling real-time detection of dehydration and electrolyte imbalances.
Additionally, introducing in-sensor data computing significantly reduced wireless communication power consumption. Previously, all raw data had to be transmitted externally, but now only the necessary results are calculated and transmitted within the sensor, reducing data transmission requirements from 400B/s to 4B/s—a 100-fold decrease.
To validate performance, the research tested the device on healthy adult subjects in four different environments: bright indoor lighting, dim lighting, infrared lighting, and complete darkness. The results showed measurement accuracy equivalent to that of commercial medical devices in all conditions A mouse model experiment confirmed accurate blood oxygen saturation measurement in hypoxic conditions.
<Frigure2.The multimodal device applying the energy harvesting and power management platform consists of i) photoplethysmography (PPG) sensor, ii) blue light dosimeter, iii) photoluminescent microfluidic channel for sweat analysis and biomarker sensors (chloride ion, glucose, and pH), and iv) temperature sensor. This device was implemented with flexible printed circuit board (fPCB) to enable attachment to the skin. A silicon substrate with a window that allows ambient light and measurement light to pass through, along with photoluminescent encapsulation layer, encapsulates the PPG, blue light dosimeter, and temperature sensors, while the photoluminescent microfluidic channel is attached below the photoluminescent encapsulation layer to collect sweat>
Professor Kyeongha Kwon of KAIST, who led the research, stated, “This technology will enable 24-hour continuous health monitoring, shifting the medical paradigm from treatment-centered to prevention-centered shifting the medical paradigm from treatment-centered to prevention-centered,” further stating that “cost savings through early diagnosis as well as strengthened technological competitiveness in the next-generation wearable healthcare market are anticipated.”
This research was published on July 1 in the international journal Nature Communications, with Do Yun Park, a doctoral student in the AI Semiconductor Graduate Program, as co–first author.
※ Paper title: Adaptive Electronics for Photovoltaic, Photoluminescent and Photometric Methods in Power Harvesting for Wireless and Wearable Sensors ※ DOI: https://doi.org/10.1038/s41467-025-60911-1 ※ URL: https://www.nature.com/articles/s41467-025-60911-1
This research was supported by the National Research Foundation of Korea (Outstanding Young Researcher Program and Regional Innovation Leading Research Center Project), the Ministry of Science and ICT and Institute of Information & Communications Technology Planning & Evaluation (IITP) AI Semiconductor Graduate Program, and the BK FOUR Program (Connected AI Education & Research Program for Industry and Society Innovation, KAIST EE).
2025.07.30 View 4488 -
KAIST's Li-Fi - Achieves 100 Times Faster Speed and Enhanced Security of Wi-Fi
- KAIST-KRISS Develop 'On-Device Encryption Optical Transmitter' Based on Eco-Friendly Quantum Dots
- New Li-Fi Platform Technology Achieves High Performance with 17.4% Device Efficiency and 29,000 nit Brightness, Simultaneously Improving Transmission Speed and Security
- Presents New Methodology for High-Speed and Encrypted Communication Through Single-Device-Based Dual-Channel Optical Modulation
< Photo 1. (Front row from left) Seungmin Shin, First Author; Professor Himchan Cho; (Back row from left) Hyungdoh Lee, Seungwoo Lee, Wonbeom Lee; (Top left) Dr. Kyung-geun Lim >
Li-Fi (Light Fidelity) is a wireless communication technology that utilizes the visible light spectrum (400-800 THz), similar to LED light, offering speeds up to 100 times faster than existing Wi-Fi (up to 224 Gbps). While it has fewer limitations in available frequency allocation and less radio interference, it is relatively vulnerable to security breaches as anyone can access it. Korean researchers have now proposed a new Li-Fi platform that overcomes the limitations of conventional optical communication devices and can simultaneously enhance both transmission speed and security.
KAIST (President Kwang Hyung Lee) announced on the 24th that Professor Himchan Cho's research team from the Department of Materials Science and Engineering, in collaboration with Dr. Kyung-geun Lim of the Korea Research Institute of Standards and Science (KRISS, President Ho-Seong Lee) under the National Research Council of Science & Technology (NST, Chairman Young-Sik Kim), has developed 'on-device encryption optical communication device' technology for the utilization of 'Li-Fi,' which is attracting attention as a next-generation ultra-high-speed data communication.
Professor Cho's team created high-efficiency light-emitting triode devices using eco-friendly quantum dots (low-toxicity and sustainable materials). The device developed by the research team is a mechanism that generates light using an electric field. Specifically, the electric field is concentrated in 'tiny holes (pinholes) in the permeable electrode' and transmitted beyond the electrode. This device utilizes this principle to simultaneously process two input data streams.
Using this principle, the research team developed a technology called 'on-device encryption optical transmitter.' The core of this technology is that the device itself converts information into light and simultaneously encrypts it. This means that enhanced security data transmission is possible without the need for complex, separate equipment.
External Quantum Efficiency (EQE) is an indicator of how efficiently electricity is converted into light, with a general commercialization standard of about 20%. The newly developed device recorded an EQE of 17.4%, and its luminance was 29,000 nit, significantly exceeding the maximum brightness of a smartphone OLED screen, which is 2,000 nit, demonstrating a brightness more than 10 times higher.
< Figure 1. Schematic diagram of the device structure developed by the research team and encrypted communication >
Furthermore, to more accurately understand how this device converts information into light, the research team used a method called 'transient electroluminescence analysis.' They analyzed the light-emitting characteristics generated by the device when voltage was instantaneously applied for very short durations (hundreds of nanoseconds = billionths of a second). Through this analysis, they investigated the movement of charges within the device at hundreds of nanoseconds, elucidating the operating mechanism of dual-channel optical modulation implemented within a single device.
Professor Himchan Cho of KAIST stated, "This research overcomes the limitations of existing optical communication devices and proposes a new communication platform that can both increase transmission speed and enhance security."
< Photo 2. Professor Himchan Cho, Department of Materials Science and Engineering >
He added, "This technology, which strengthens security without additional equipment and simultaneously enables encryption and transmission, can be widely applied in various fields where security is crucial in the future."
This research, with Seungmin Shin, a Ph.D. candidate at KAIST's Department of Materials Science and Engineering, participating as the first author, and Professor Himchan Cho and Dr. Kyung-geun Lim of KRISS as co-corresponding authors, was published in the international journal 'Advanced Materials' on May 30th and was selected as an inside front cover paper.※ Paper Title: High-Efficiency Quantum Dot Permeable electrode Light-Emitting Triodes for Visible-Light Communications and On-Device Data Encryption※ DOI: https://doi.org/10.1002/adma.202503189
This research was supported by the National Research Foundation of Korea, the National Research Council of Science & Technology (NST), and the Korea Institute for Advancement of Technology.
2025.06.24 View 8056