Development of the Ultrasensitive Biosensor for Detecting Early-Stage Liver Fibrosis Without Tissue Biopsy
Bio-Mechatronic Engineering
Prof. PARK, JINSUNG
Institute of Confucian Philosophy and Culture Publishes Buddhist-Confucian Dialogue with a world-renowned press
Confucian and Oriental Studies
Prof. KIM, DOIL
Development of the Ultrasensitive Biosensor for Detecting Early-Stage Liver Fibrosis Without Tissue Biopsy
2026-07-09
Successfully Hosts NGPT 2026 and Inaugural NPS Launch Ceremony SKKU successfully hosted the 8th International Conference on Nanogenerators and Piezotronics (NGPT 2026) from June 9 to 12 at its Humanities and Social Sciences Campus in Seoul. NGPT is one of the world’s leading international conferences in the fields of nanogenerators, piezotronics, self-powered sensors, and energy harvesting. The conference serves as a premier platform where researchers share the latest scientific advances and discuss future technological directions. Having previously hosted NGPT in 2018, SKKU welcomed the conference for the second time this year. More than 500 researchers, students, and industry representatives from 21 countries, including the United States, China, Germany, the United Kingdom, Canada, and Singapore, participated in the event. The conference featured presentations on a wide range of cutting-edge topics, including self-powered sensors, wearable electronics, AI-integrated sensing technologies, bioelectronics, energy harvesting, and sustainable energy technologies. Participants actively exchanged ideas through keynote lectures, tutorial sessions, invited talks, oral presentations, and poster sessions. ▲ Professor Zhong Lin Wang (Georgia Institute of Technology) delivers opening remarks. Among the distinguished speakers were Professor Zhong Lin Wang of Georgia Institute of Technology, the pioneer of nanogenerators and piezotronics; Professor Mark Hersam of Northwestern University, a world-renowned expert in nanomaterials and electronic devices; and Professor Orlando J. Rojas of The University of British Columbia, a leading scholar in sustainable biomaterials. Together with other internationally recognized researchers, they discussed the future directions of next-generation energy and sensor technologies. Editors from top-tier journals, including Nano Energy, Advanced Materials, and Joule, also attended the conference, sharing insights on emerging research trends and academic publishing strategies. In addition, a special issue featuring outstanding research presented at NGPT 2026 is planned, which is expected to further disseminate the conference’s scientific contributions and foster follow-up studies and international collaborations. A particularly significant milestone of NGPT 2026 was the official launch of the Nanogenerators and Piezotronics Society (NPS), an international academic organization established to promote global collaboration and scholarly advancement in the field. Researchers from around the world gathered for the inaugural ceremony to share the society’s vision and discuss future directions for international research cooperation and academic exchange. ▲ Professor Jeong Min Baik of the Department of Materials Science and Engineering delivers congratulatory remarks. Professor Jung Min Baik of the Department of Materials Science and Engineering, Chair of the Organizing Committee, stated, “It is especially meaningful for SKKU to host NGPT once again following the 2018 conference. We hope this conference not only provides an opportunity for researchers worldwide to share their latest findings and discuss future technological visions, but also serves as a catalyst for strengthening global research collaboration through the launch of the Nanogenerators and Piezotronics Society."
2026-06-15
A light-color-programmed artificial synapse for brain-like balanced learning ▲ Professor Sae Byeok Jo (corresponding author) and Professor Wooseok Yang (co-correspoding author) The human brain actively keeps “learning” in balance, by holding on to what matters and letting go of what does not. Researchers of SKKU have now reproduced this ability in a semiconductor device, using the color of light to strengthen (remember) or weaken (forget) an artificial synapse's memory. Remarkably, the key ingredient is a material 'defect' that engineers usually try to eliminate. The study appears in the journal Nature Communications in May 2026. Modern artificial intelligence is extraordinarily power-hungry. Training a single generative model can consume as much electricity as a small city. The brain, by contrast, outperforms supercomputers on far less energy than a light bulb, because it stores and processes information at the same place, the synapse. This has driven intense interest in neuromorphic (brain-inspired) computing, and especially in light-driven 'photonic synapses' that promise ultralow-power, high-speed operation. A long-standing obstacle, however, is that conventional artificial synapses use the same control knob for both 'remembering' (potentiation) and 'forgetting' (depression). This makes the learning balance collapse over time-weights either saturate (runaway) or fade away (quiescence), erasing what was learned. The brain avoids this through homeostatic plasticity, but artificial hardware has had to mimic it with costly extra software. The team led by Professor Sae Byeok Jo and Professor Wooseok Yang (Sungkyunkwan University) solved this by embracing a defect rather than removing it. In silver bismuth sulfide (AgBiS2), a next-generation light-absorbing semiconductor, a slight, controlled disorder in the ionic arrangement (so-called cation disorder) creates 'traps' that hold photo-generated electrons for a long time. This is a drawback for fast detectors, but it makes the material behave like a 'natural memory' that retains information even after the power is off. By precisely tuning this disorder and stacking a near-infrared-absorbing molecular layer on top, the researchers turned the color of incident light into a learning switch. Near-infrared light triggered 'accelerated learning,' boosting the synaptic connection more than 13-fold, while blue light drove 'accelerated forgetting,' rapidly weakening it. Using ultrafast laser spectroscopy that resolves events down to a quadrillionth of a second, the team directly confirmed that the two colors send electrons along opposite pathways-filling versus emptying the traps. In a handwritten-digit recognition simulation, the conventional neural networks using a single mechanism lost their memory within 200 training rounds, whereas the new wavelength-orthogonal scheme kept recognizing patterns stably over 1,000 rounds-demonstrating brain-like balanced learning at the hardware level. Professor Jo said, "Knowing how to forget is as important as knowing how to remember. The essence of this work is that we separated those two functions by the color of light, and revived what was considered a defect into a self-balancing learning function for AI hardware." The approach is not limited to one material, and all processing uses low-temperature, ink-based solution methods compatible with existing semiconductor lines. The researchers expect the technology to contribute to light-based neuromorphic computing, low-power AI accelerators, in-sensor computing, and machine-vision systems for autonomous vehicles and robots-as well as 'artificial eyes' (artificial retinas) that can see and remember. ▲ By the color of light, a single disorder-engineered synapse selectively strengthens or weakens its memory, enabling brain-like homeostatic learning.
2026-06-11
Development of World's First High-Performance Lewis Acid Secondary Silylium Organocatalyst -Reductive sulfonamidation of ketones, previously impossible, was achieved using new 'diethylsilylium ion’ -Practical utility demonstrated through three-step scale-up synthesis of the antidiabetic drug sitagliptin ▲SKKU Prof. Han-Yong Bae (corresponding authors), Dr. Woo Hee Kim, Dr. Muhammad Israr (co 1st authors) A research team led by Professor Han-Yong Bae of the Department of Chemistry at Sungkyunkwan University, in collaboration with Professor Junsuk Huh of the Departments of Chemistry and Institute of Quantum Information Technology at Yonsei University, announced the first development of a novel silylium Lewis acid organocatalysis. This technology employs an ion-pair catalyst combining a diethylsilylium — with a weakly coordinating anion, enabling the direct installation of sulfonamide groups into functionalized ketone compounds, including β-ketoesters, which had previously been difficult to react using conventional catalytic methods. The catalytic system developed in this study represents a major advance in the field of reductive sulfonamidation, which enables precise control over nitrogen–carbon bond formation in the synthesis of complex molecular structures. Instead of conventional transition-metal catalysts or high-pressure hydrogen gas, the researchers implemented new catalytic reaction conditions in which a powerful silylium ion pair is generated in situ by combining trityl tetrakis(pentafluorophenyl)borate with diethylsilane. Diethylsilane simultaneously serves dual roles as both a reductant and a silylium precursor, while the resulting novel catalyst operates with precise control over not only reaction rate but also substrate activation and selectivity. Notably, this study achieved in a single reaction vessel a series of steps — including the reduction of ketimine intermediates — for which conventional tertiary silylium catalysts had shown very low conversion rates. Through this reaction, alkyl β-amino ester derivatives were successfully synthesized in yields of up to 95%, realizing an sustainable process in which scale-up reactions proceed smoothly without solvent, metal, hydrogen gas, or other additives. ▲ Reductive sulfonamidation of functionalized ketones and scale-up synthesis of the antidiabetic drug sitagliptin enabled by a new secondary silylium organocatalyst In addition to experimental results, the research team elucidated in detail how this new catalytic system operates through density functional theory (DFT) calculations, nuclear magnetic resonance (NMR) spectroscopy, and high-resolution mass spectrometry (HR-MS). Beyond merely developing a new reaction, the team scientifically demonstrated that secondary silylium ions exhibit stronger Lewis acidity than tertiary silylium ions due to lower steric hindrance, and that they activate substrates more effectively in ion-pair formation with weakly coordinating anions. Professor Han-Yong Bae stated, "This study is highly significant in that it proposes a new approach of in situ catalytic system based on secondary silylium ions," adding, "We expect it to find broad application in various carbon–heteroatom bond-forming reactions going forward.“ Professor Junsuk Huh noted, "Validated through both experimental and theoretical approaches, this technology will serve as a fundamental platform applicable to the synthesis of high-value compounds including natural products, pharmaceuticals, and diverse organic materials — as exemplified by the antidiabetic drug sitagliptin.“ This research was conducted with support from the Ministry of Science, ICT, and Future Planning, the Ministry of Education, the Korea Health Industry Development Institute, Sungkyunkwan University, and Yonsei University. It was published online on May 26, 2026, in the prestigious international journal Advanced Science. Title: A Strong Lewis Acidic Diethylsilylium Catalyst for Direct Sulfonamidation of Challenging Ketones Access Paper: https://advanced.onlinelibrary.wiley.com/doi/10.1002/advs.75783
2026-06-05
Revealing Chemical Pathway for Next-Generation Infrared III–V Nanocrystals - Metal–amide chemistry provides a rational approach to controlling heavy-pnictogen reduction, paving the way for safer and more scalable semiconductor quantum dots ▲ Research Team: From left: Hyoin Kim, Professor Sohee Jeong, Professor Maksym V. Kovalenko of ETH Zurich, and Dr. Meeree Kim. A research team led by Professor Sohee Jeong has uncovered a key chemical pathway for the controlled synthesis of III–V semiconductor quantum dots, a class of next-generation infrared materials expected to play an important role in autonomous driving sensors, smart sensing systems, night-vision devices, and short-wave infrared optoelectronics. The study was conducted in close international collaboration with Professor Maksym V. Kovalenko’s group (SIEST faculty) at ETH Zurich and was published in the Journal of the American Chemical Society under the title “Metal–Amide Chemistry Enables Controlled Heavy-Pnictogen Reduction for Colloidal III–V Nanocrystal Synthesis.” As infrared-based technologies become increasingly important in daily life, including nighttime object recognition for autonomous vehicles and smart home devices, the demand for high-performance infrared semiconductor materials continues to grow. III–V semiconductor quantum dots such as indium arsenide and indium antimonide have attracted attention for their excellent infrared optical properties and their potential as less toxic, Pb- and Hg-free material platforms. However, the lack of practical precursor systems for heavy-pnictogen (As and Sb) and limited understanding of their underlying precursor chemistry have restricted broader synthetic design and scalability. To address this challenge, Professor Jeong’s team decoupled the activation of heavy-pnictogen(III) precursors from quantum dot formation. Through this approach, the researchers were able to observe how heavy-pnictogen(III) precursors are reduced and gain reactivity before forming nanocrystals. The team found that metal–amide species formed from metal–alkyl reagents and primary amines play a central role in controlling the reduction of heavy-pnictogen(III) precursors. In particular, the study revealed that these metal–amide complexes undergo thermally activated amide-to-imine oxidation and mediate the reduction of heavy-pnictogen precursors. By adjusting the reduction temperature and metal-cation environment, the researchers could access partially reduced precursor states suitable for III–V nanocrystal synthesis. This finding marks a step toward moving from empirical synthesis toward a chemistry-based design strategy. Rather than adding all reactants at once and relying on trial-and-error optimization, the new approach enables researchers to prepare precursors with controlled reactivity in advance and then use them for nanocrystal growth. Using this strategy, the team successfully synthesized indium arsenide and indium antimonide nanocrystals without adding extra reducing agents during the nanocrystal growth step. This compatibility with pre-reduced precursors allows the synthesis to be adapted to various platforms, including heat-up, hot-injection, and continuous-injection methods, offering greater flexibility for scalable nanocrystal production. The work systematically reveals a chemical mechanism hidden within a complex semiconductor synthesis process. It demonstrates how fundamental chemical principles can guide the design of advanced materials for technologies such as autonomous driving sensors and night-vision cameras. This study is significant in that it establishes a rational precursor design principle for heavy-pnictogen-based III–V nanocrystals. The findings are expected to contribute to the development of safer, more reproducible, and more scalable infrared semiconductor materials for next-generation smart sensors, imaging systems, and optoelectronic devices. The research was supported by the Ministry of Science and ICT, the National Research Foundation of Korea, Samsung Electronics, and related research infrastructure programs. ▲ Research Figure: Schematic illustration of the heavy-pnictogen reduction mechanism identified by the research team (top) and optical/electron microscopy characterization of synthesized III–V semiconductor nanocrystals, including InAs and InSb (bottom). ※ Title: Metal–Amide Chemistry Enables Controlled Heavy-Pnictogen Reduction for Colloidal III–V Nanocrystal Synthesis ※ Journal: Journal of the American Chemical Society ※ DOI: https://pubs.acs.org/doi/10.1021/jacs.6c02928
2026-05-07
SKKU Researchers Develop Breakthrough “Gas Battery” Technology that Generates Electricity from Greenhouse Gases - Simultaneous greenhouse gas capture and electricity generation marks a paradigm shift from energy-consuming to energy-producing systems - Expected to enable carbon-neutral next-generation energy platforms, including self-powered IoT and industrial emission reduction ▲ (From left) Professor Ji-Soo Jang of Sungkyunkwan University, Professor Taekwang Yoon of Ajou University, and Professor Hansel Kim of Chungbuk National University Professor Ji-Soo Jang from the Department of Nanoengineering, in collaboration with Professor Taekwang Yoon of Ajou University and Professor Hansel Kim of Chungbuk National University, has developed a novel energy device that generates electricity during the process of capturing greenhouse gases. The research team introduced a new concept device termed the Gas Capture and Electricity Generator (GCEG), which produces electrical power as greenhouse gases are adsorbed from the atmosphere. This innovation goes beyond conventional approaches that merely capture greenhouse gases, transforming them into a usable energy resource. Amid growing global efforts to address climate change, carbon capture, utilization, and storage (CCUS) technologies have gained attention. However, existing CCUS systems typically require substantial energy input for gas collection and processing. To overcome this limitation, the research team proposed a fundamentally new mechanism that directly converts the physicochemical energy generated during gas adsorption on electrode surfaces into electrical energy. The developed GCEG device consists of an asymmetric structure combining carbon-based electrodes with hydrogel materials. When greenhouse gases such as nitrogen oxides (NOx) or carbon dioxide (CO₂) are adsorbed, charge redistribution and ion migration occur within the device, enabling continuous direct current (DC) power generation without any external power source. In essence, atmospheric pollutants act as the “fuel” for electricity generation, simultaneously purifying the environment while supplying energy. ▲Schematic illustration explaining the working principle of the greenhouse gas adsorption-based power generation device, “Gas Capture and Electricity Generator (GCEG)” This technology is expected to be widely applicable in self-powered smart environmental sensors, battery-free IoT systems, and industrial facilities where large volumes of emissions are generated. In such settings, it could enable simultaneous energy harvesting and carbon reduction. In particular, its integration into distributed energy systems is anticipated to accelerate the realization of carbon neutrality. Professor Ji-Soo Jang stated, “This research demonstrates that greenhouse gases are not merely pollutants to be managed, but can serve as a new energy resource. We aim to further develop this technology into an environmental platform that not only achieves carbon neutrality but also generates energy.” ▲ Cover image of the paper on the greenhouse gas adsorption-based power generation device, “Gas Capture and Electricity Generator (GCEG)” The research findings were published in Energy & Environmental Science (Impact Factor: 31.0), one of the world’s leading journals in materials science, and were selected as a Front Cover article in recognition of their excellence and originality. ※ Paper: Electrical power generation from asymmetric greenhouse gas capture ※ Journal: Energy & Environmental Science (IF: 31.0) ※ DOI: https://doi.org/10.1039/D5EE06789H
2026-04-16
Roll-to-roll manufacturing marks a major step toward commercialization of flat optics ▲ (From left) Professor Gyoujin Cho of Sungkyunkwan University, Professor Junsuk Rho of POSTECH, and Inki Kim of Sungkyunkwan University. A new study published in Nature, entitled “300-unit-per-second roll-to-roll manufacturing of visible metalenses,” addresses long-standing technical barriers that have hindered the commercialization of metalenses. A collaborative research group led by Professor Gyoujin Cho and Professor Inki Kim (Department of Biophysics, Sungkyunkwan University), in partnership with Professor Junsuk Rho (Department of Mechanical Engineering, POSTECH), has developed a fully automated roll-to-roll manufacturing platform capable of producing large-area visible metalenses at a rate of 300 units per second, marking a major breakthrough in translating metasurface technology from the laboratory to real-world industrial deployment. Metalenses are flat, ultrathin optical components composed of two-dimensional arrays of subwavelength nanostructures that precisely control light, offering a compact and lightweight alternative to conventional bulky lenses. By engineering the phase, amplitude and polarization of light at the nanoscale, they enable advanced optical functions in an exceptionally thin form factor, making them a promising candidate for the next revolution in optical technology. However, despite their enormous potential, the industrial adoption of metalenses has been constrained by a major manufacturing challenge: how to produce high-performance devices over large areas, at high speed and low cost, while maintaining the uniformity and yield required for practical industrial applications. To overcome this limitation, the research team first produced 12-inch silicon master stamp by replicating a single pattern originally fabricated by electron beam lithography through deep-ultraviolet ArF photolithography. The team then employed a custom-built roll-to-roll nanoimprint lithography system that operates in a fully automated manner at the 12-inch scale and achieves feature resolution down to 80 nm with a remarkable imprinting speed of one 12-inch mould every 1.5 seconds equivalent to a lens throughput of 300 metalenses per second, each with a diameter of 1 cm. This throughput is approximately two orders of magnitude higher than that of conventional nanoimprint lithography systems. To enable scalable and low-cost manufacturing, a flexible polymer replica mould was developed by directly replicating a master stamp onto a polyethylene terephthalate (PET) backplane foil using an ultraviolet (UV)-curable resin. This approach eliminates the need for the conventional electroformed nickel shim - a major bottleneck in roll-to-roll manufacturing, thereby substantially reduces production cost and manufacturing time by allowing many flexible moulds to be rapidly produced from a single master wafer. The replicated metalenses are subsequently coated with a high-index titanium dioxide (TiO₂) layer via atomic layer deposition (ALD), a well-established and scalable industrial process, to further enhance optical performance. ▲ Figure 1. Mass production process of metalens based on roll-to-roll nanoimprinting (a) Fabrication of polymer molds and roll-to-roll operation utilizing them (b) Photograph of the roll-to-roll nanoimprinting facility independently designed by the research team For the first time, the team demonstrated the mass production of 200-metre-long metalens arrays with high yield and consistent functionality across a large area, validating the effectiveness of the roll-to-roll nanoimprint lithography approach for the scalable manufacture of high-quality metasurfaces. This study represents a significant advance in the scalable and sustainable production of metalenses, paving the way for the commercialization of metaphotonic devices. ▲ Figure 2. Fabricated large-area metalens array (a) Photograph of a metalens array film fabricated via a 200m-long continuous process (b) Photograph of a fabricated 12-inch wafer-sized metalens array (c) Image of metalens nanostructures captured via SEM According to Professor Kim: “Metasurfaces have long been seen as a powerful platform for next-generation optics, but scalable manufacturing has remained a major bottleneck. By demonstrating roll-to-roll production of visible metalenses at 300 units per second, we show that mass production is possible. The throughput can be scaled even further by increasing the size of the imprint rollers and optimizing the mould design. Moreover, if our roll-to-roll technology is also applied to mould manufacturing, the cost of each metalens could become almost negligible. We believe this work offers a compelling route for translating metasurface optics into everyday technologies” The team expects that the approach could support broader industrial efforts to integrate metasurface optics into next-generation imaging, display, sensing and consumer electronic devices. ※ Paper Title: 300-unit-per-second roll-to-roll manufacturing of visible metalenses ※ Journal: Nature (2026) ※ DOI: 10.1038/s41586-026-10369-y
2026-04-16
Department of Child Psychology and Education Demonstrates Global Competitiveness with Three SSCI Publications and Overseas Advancement ▲ ((From left) Seowoo Lee, Ran Kang, and JIANG ZEKAI, Department of Child Psychology and Education The Department of Child Psychology and Education (Chair: Professor Taekyoung Lee) is demonstrating its global research competitiveness through the publication of three SSCI-indexed international journal articles and the overseas advancement of BK-participating graduate students. In particular, the consecutive publication of research by BK-participating graduate students in SSCI-level international journals highlights the department’s research capacity on a global stage. Student Seowoo Lee published a study analyzing adolescents’ psychopathological symptoms and resilience processes in the SSCI-indexed international journal Journal of Youth and Adolescence (top 19.6% in Developmental Psychology, 2025). Student Ran Kang had a study on stress interactions and parenting efficacy in multicultural families accepted for publication in the Journal of Family Psychology (top 31.1% in Family Studies, 2026). In addition, JIANG ZEKAI published a study examining the relationships among cultural stress, adaptation processes, and mental health in multicultural adolescents in Cultural Diversity and Ethnic Minority Psychology (top 2.5% in Ethnic Studies, 2024). The research laboratory of Professor Taekyoung Lee, who supervised these students, has consistently produced publications in international journals, focusing on adolescent development. Furthermore, graduate alumni of the Department of Child Psychology and Education (supervised by Professor Hana Song and Professor Taekyoung Lee) have recently been appointed as full-time faculty members at universities in the United States, China, and Mongolia, and have also advanced into global IT companies such as Tencent Technology, demonstrating active engagement across diverse fields. Currently, the Department of Child Psychology and Education is expanding international collaborative research and academic exchange based on its network with institutions such as the University of Texas at Austin, Vanderbilt University, The Hebrew University of Jerusalem (Israel), Victoria University of Wellington (New Zealand), and Mongolian National University of Education (Mongolia).
2026-04-07
SKKU Professor Tae-Youn Park, “Does Pay Transparency Reduce Wage Inequality?” (HBR) A study by Professor Tae-Youn Park of the SKKU Business School, examining the implications of pay transparency policies for the labor market, has been published online in the Harvard Business Review (HBR), a leading practitioner-oriented outlet in the field of business and management. The HBR article is based on joint research conducted by Professor Tae-Youn Park of Sungkyunkwan University, Professor Alice Lee of Cornell University, and Professor Sungyong Chang of Cornell University. This HBR article is based on the forthcoming academic paper to be published in the Journal of Applied Psychology. In recent years, a growing number of countries, including the United States, have adopted and expanded pay transparency policies to reduce information asymmetry in the labor market and address unfair wage inequality, such as gender pay gaps. However, most policies focus only on whether pay information is disclosed, without providing clear guidelines on the appropriate width of disclosed pay ranges. As a result, substantial variation in pay ranges has emerged across firms even for the same job. For example, for the same software engineer position in California, Tesla posts a salary range of $83,000 to $418,000, whereas Uber offers a much narrower range of $174,000 to $194,000. Drawing on multiple studies, including analyses of approximately 10 million job postings, Professor Park and his coauthors find that wider posted pay ranges are associated with a lower proportion of female applicants. This pattern can be explained by the fact that wider ranges signal greater uncertainty in potential compensation, even when the midpoint of the range is identical. On average, female applicants—who tend to exhibit higher levels of risk aversion—are more likely to apply to positions with narrower pay ranges. These differences at the application stage carry over into the salary negotiation stage. Applicants who choose positions with narrower pay ranges tend to have lower expectations for salary increases compared to those who apply to positions with wider ranges. Empirically, they also request approximately $3,600 less in salary. Such initial pay differences may accumulate over time through promotions, bonuses, and future salary growth, potentially leading to persistent long-term wage gaps. In other words, a preference for narrower pay ranges driven by risk aversion may inadvertently contribute to widening gender pay inequality. Importantly, the research also shows that this issue can be mitigated through simple informational interventions. When pay ranges are accompanied by additional information—such as typical starting salaries and the criteria used to determine pay (e.g., experience and skills)—the gender gap in application rates decreases, and differences in negotiation behavior across pay range conditions are significantly reduced. Based on these findings, Professor Park emphasizes that “firms should go beyond merely disclosing pay information and provide meaningful context to applicants,” and that “policymakers should take these considerations into account when designing pay transparency regulations.” This research was supported by the Sungkyunkwan University Academic Research Support Program (Samsung Research Fund).
2026-03-24
Revealing the Origin of Polarity Inversion in Polymer Semiconductors - A key insight into next-generation flexible electronics and thermoelectric devices ▲ (From left to right) Prof. Boseok Kang (Sungkyunkwan University), Hoimin Kim (Ph.D. candidate), Prof. Yun-Hi Kim (Gyeongsang National University), Landep Ayuningtias (Ph.D. candidate), and Prof. Han-Sol Lee (Gachon University) A research team led by Prof. Boseok Kang at Sungkyunkwan University has uncovered the origin of polarity inversion—a long-standing phenomenon in polymer semiconductors that occurs only in certain materials—attracting significant attention. The National Research Foundation of Korea (NRF) announced that the team, in collaboration with Prof. Yun-Hi Kim (Gyeongsang National University) and Prof. Han-Sol Lee (Gachon University), has elucidated the mechanism behind polarity inversion in polymer semiconductors. This work was supported by the Ministry of Science and ICT (MSIT) of Korea and the NRF, and was published online on February 15 in the journal Advanced Functional Materials. Polymer semiconductors are considered key materials for next-generation electronics due to their lightweight, flexibility, and solution processability, enabling low-cost fabrication via printing or coating techniques. It has been reported that increasing the doping level in polymer semiconductors can induce polarity inversion, where charge transport switches from p-type to n-type. This phenomenon enables both p-type and n-type behavior within a single material, simplifying device structures and improving manufacturing efficiency. However, polarity inversion has been observed only in a limited number of polymers, and the fundamental reason why it occurs in some systems but not others—despite similar doping conditions—remains unclear. To address this, the research team systematically compared polymer semiconductors with different molecular structures and investigated the conditions required for polarity inversion. They found that polarity inversion occurs only when the amount of dopant absorbed into the polymer film exceeds a critical threshold. Beyond this level, dopant-derived anions interact strongly with the polymer, altering charge transport behavior and inducing a transition from p-type to n-type conduction. In contrast, when dopant uptake is insufficient, polarity inversion does not occur. These results reveal that polarity inversion is not determined solely by the doping process itself, but by the polymer’s molecular structure, which governs dopant uptake and polymer–dopant interactions. This study provides a systematic explanation for why polarity inversion appears only in certain polymers and offers important design guidelines for enabling controllable polarity switching or stable n-type behavior in polymer semiconductors. The researchers note that further studies are needed to explore a broader range of dopant systems and practical device conditions. Prof. Boseok Kang commented, “The current device performance is still at an early stage, and further improvements will require optimization of both molecular design and device architecture.” ▲ Schematic illustration of p-type to n-type polarity inversion in polymer semiconductors as a function of dopant uptake capability
2026-03-19
