신소재공학과

Research 2026년 09월 08일 화요일

Perovskite Solar Cells Hold Up Under Extreme Temperature Swings

Summary The advent of self-assembled monolayer (SAM)-based hole-selective layers (HSLs) has revolutionized inverted perovskite solar cells (i-PSCs) by enabling record efficiencies, but they are constrained by incomplete surface coverage and interfacial heterogeneity. We devise topology-governed SAMs featuring isomeric linker patterns (LY-ortho [o], LY-meta [m], and LY-para [p]) and uncover the principle that conformational ordering dictates surface coverage and interfacial interaction coupling with perovskite. The topology-optimized LY-m forms a homogeneously dense, stable HSL with superior energy alignment and interfacial passivation. Devices incorporating LY-m achieve a record-high open-circuit voltage of 1.231 V, accompanied by an efficiency of 26.39% (certified 26.37%), while maintaining robust operational stability and scalability. Beyond laboratory metrics, LY-m-based devices withstand −100°C to 100°C thermal cycling with only ∼9% loss, far exceeding the operational limits of state-of-the-art commercial SAMs, while maintaining over 80% of their initial performance at 85°C (T80 ≅ 2,000 h). This work resolves the long-standing role of linker topology and paves the way for extreme-environment-resilient and scalable perovskite photovoltaics. Temperature swings are a major challenge for perovskite solar cells (PSCs), particularly in environments such as space, where materials may repeatedly move between extreme cold and heat. Led by Professors Changduk Yang and Seungjae Shin of the Department of Energy and Chemical Engineering and Professor Myung Hoon Song of the Department of Materials Science and Engineering at UNIST, the team developed perovskite solar cells that withstand such extremes by stabilizing a critical molecular interface. The cells retained about 91% of their initial efficiency after cycling between −100°C and +100°C, with a certified power-conversion efficiency of 26.37%. The key to this advancement is a self-assembled monolayer (SAM), a molecule-thin layer that helps move electrical charges between the electrode and the perovskite absorber. Under severe thermal stress, SAM molecules can shift or cluster, disrupting the interface and degrading performance. The team addressed this problem by changing where the molecular components of the SAM connect. They synthesized three versions with different linker positions and found that LY-m adopted a tilted orientation, allowing its molecules to pack densely and uniformly on the electrode. This arrangement also suppresses the molecular reorganization that can occur under large temperature swings. In thermal-cycling tests, LY-m cells were held alternately at −100°C and +100°C for 30 minutes at each temperature over 16 cycles. They remained operational with only about a 9% loss in efficiency, while cells using a commercial SAM failed under the same conditions. LY-m cells also reached a peak efficiency of 26.39%, with a certified efficiency of 26.37% and an open-circuit voltage of 1.231 V. At 85°C, they maintained more than 80% of their initial performance for approximately 2,000 hours. The approach also performed well at larger scales: a 1 cm² cell achieved 23.25% efficiency, while a 3 × 1 cm² mini-module reached 21.20%. “By changing only the position of the molecular connection, we were able to control how the molecules pack on the electrode,” said Professor Yang. “The resulting interface combines high efficiency with thermal stability, offering a promising route toward perovskite photovoltaics for environments with extreme temperature variations.” The study has been participated by Seunglok Lee and Jeewon Park of the Department of Energy and Chemical Engineering and Jingyu Yang of the Department of Materials Science and Engineering at UNIST, as co-first authors of the study. Published in Joule on August 3, the study has been supported by the Nano & Material Technology Development Program through the National Research Foundation (NRF) of Korea and the InnoCORE program of the Ministry of Science and ICT (MSIT). Journal Reference Seunglok Lee, Jinkyu Yang, Jeewon Park, et al., "Topology-governed self-assembled monolayers enable perovskite solar cells stable at −100°C to +100°C," Joule , (2026).

Research 2026년 09월 03일 목요일

Reducing Charge Loss in Organic Photoanodes for Solar Water Splitting

Abstract Organic photoelectrochemical (PEC) cells for solar water splitting typically utilize bulk heterojunction (BHJ) structures to circumvent the intrinsically short exciton diffusion lengths of organic semiconductors. However, stochastic donor/acceptor networks in BHJs often result in disordered interfacial contacts, leading to severe charge recombination. Herein, we report a pseudo-bilayer (PS-Bi) organic photoanode featuring a vertically ordered donor–acceptor configuration established via sequential deposition. Our systematic investigation reveals that this PS-Bi structure promotes selective charge transport and suppresses recombination due to its high domain purity, thereby facilitating efficient charge transfer at the interface. Consequently, the optimized PS-Bi photoanodes deliver an enhanced average photocurrent density (Jph) of 1.75 ± 0.03 mA cm−2 at 1.23 V versus the reversible hydrogen electrode for solar water oxidation, while simultaneously exhibiting a significant cathodic onset shift and extended operational stability compared to their BHJ counterparts (Jph = 1.44 ± 0.07 mA cm−2). This study demonstrates that employing the PS-Bi structure is a promising strategy for achieving high-performance and stable organic PEC systems for sustainable solar fuel production. Producing hydrogen from sunlight depends in part on how efficiently a photoelectrode can separate and move electrical charges. In organic photoelectrodes, however, the conventional practice of mixing semiconductor materials can create disordered pathways that allow those charges to recombine, reducing both performance and stability. A research team, led by Professors Han Hee Cho, Moon Kee Choi, and Myung Hoon Song of the Department of Materials Science and Engineering at UNIST, working with researchers at École Polytechnique Fédérale de Lausanne (EPFL), has developed an organic photoanode with a more ordered internal structure. The new design improved photocurrent by about 22% while extending operational stability. The team created what is known as a pseudo-bilayer (PS-Bi) structure by depositing two organic semiconductor materials in sequence. As the second layer is applied, it partially penetrates the first, forming a mixed region at the interface while preserving more distinct layers above and below. Conventional organic photoelectrodes typically use a bulk heterojunction (BHJ), in which donor and acceptor materials are mixed throughout the film. This arrangement helps generate and separate charges, but its irregular internal pathways can also bring electrons and holes back together before they contribute to the chemical reaction. The PS-Bi combines the advantages of both approaches. Charges are generated and separated in the mixed region, while the more ordered layers guide electrons and holes in different directions. This reduces recombination and allows more of the generated charge to drive water oxidation. In tests, the PS-Bi photoanodes achieved an average photocurrent density of 1.75 mA cm⁻², compared with 1.44 mA cm⁻² for conventional BHJ photoanodes, an increase of about 22%. The voltage required to initiate water oxidation also fell from 0.35 V to 0.15 V, allowing the reaction to begin with less external electrical input. The structural change also improved durability. Based on the time required for photocurrent density to fall to 0.5 mA cm⁻², the pseudo-bilayer photoanodes remained operational substantially longer than their BHJ counterparts. The researchers also found that the two structures degrade differently. In BHJ photoanodes, highly reactive holes can damage the organic semiconductor within the intermixed structure. The more ordered pseudo-bilayer reduces damage within the donor–acceptor region, helping the photoanode maintain its performance for longer. “Conventional organic photoelectrodes mix donor and acceptor materials throughout the film, which can lead to charge losses and faster degradation,” said Professor Cho. “By controlling how the two materials are arranged, we were able to improve both charge transport and operational stability.” He further added, “The lower operating voltage could also help in the development of systems that ultimately produce hydrogen using sunlight without an external electrical bias.” The study was published online in Chemical Engineering Journal on July 16, 2026. The research was supported by the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (MSIT), and the InnoCORE program. Journal Reference Gyu Won Chae, Seong Rae Kang, Jin Su Park, et al. , “A pseudo-bilayer organic photoanode for solar water oxidation,” Chem. Eng. J., (2026).

Research 2026년 09월 02일 수요일

New Process Shields 2D Semiconductors from Fabrication Residue

Abstract Achieving the theoretical performance of 2D molybdenum disulfide (MoS2) electronics is currently bottlenecked by interfacial contamination derived from lithographic processing. A critical, yet often overlooked, mechanism is the interaction between photoresist (PR) and plasma, which chemically alters the interface. In this work, we elucidate the atomistic origin of this degradation: theoretical calculations based on molecular dynamics (MD) and density functional theory (DFT) reveal that plasma exposure functionalizes the PR with oxygen, drastically increasing its adsorption energy on the MoS2 surface from −1.15 to −2.36 eV. This doubling of adsorption energy creates thermodynamically stable, hardened residues that resist conventional removal methods. To overcome this fundamental limitation, we introduce a universal prevention-first strategy: Sacrificial Metal Mask Lithography. By utilizing a sacrificial layer to physically isolate the channel, we shield the MoS2 from reactive plasma species, preventing the formation of hardened residue entirely. This strategy results in a ten-fold reduction in contact resistance (RC) from 2.59 × 106 Ω·µm to 2.58 × 105 Ω·µm and an order-of-magnitude enhancement in on-current. Crucially, we demonstrate the universality of this method by successfully applying it to top-gated transistor arrays, electron-beam lithography (EBL), and atomic layer deposition (ALD)-synthesized films. Two-dimensional (2D) semiconductors, such as molybdenum disulfide (MoS2) hold promise for smaller, thinner electronics, but their extreme thinness also makes them particularly vulnerable to contamination during fabrication. Even small amounts of residue can interfere with electrical performance. A research team, led by Professor Myung-Soo Kim of the Department of Electrical Engineering and Professor Byoung Jo Kim of the Graduate School of Semiconductor Materials and Devices Engineering at UNIST, has developed a fabrication method that protects MoS2 from photoresist (PR) residue. The approach uses a thin, removable metal layer to keep the residue from reaching the semiconductor surface. PR is a light-sensitive material used to pattern circuits during semiconductor fabrication. When exposed to plasma, however, it can leave residue on MoS2 that conventional solvents struggle to remove. More aggressive cleaning can damage or even detach the atomically thin material from its substrate. Rather than removing the residue after it forms, the researchers prevent it from reaching the MoS2 in the first place. They place a 5-nanometer-thick metal layer over the semiconductor before patterning. Once fabrication is complete, the metal is dissolved, carrying the accumulated residue with it. Transistors made with the new process had a contact resistance of 2.58 × 10⁵ Ω·μm, about one-tenth that of devices made conventionally. Their on-current, or the current flowing when the transistor is switched on, increased by roughly tenfold. The researchers also found no clear damage to the crystal structure of MoS2 after the metal layer was removed. The team also uncovered why the residue is so difficult to remove. Molecular-level calculations showed that plasma exposure introduces oxygen into the PR, changing its chemistry and causing it to bind much more strongly to MoS2. The calculated adsorption energy shifted from −1.15 to −2.36 eV, roughly doubling the strength of the interaction. “This process can be used not only with conventional semiconductor patterning, but also with electron-beam lithography for finer features,” said Dahyun Kim, first author of the study. “We also found that it works with MoS2 produced by different synthesis methods.” The researchers tested the method with top-gated transistor arrays, electron-beam lithography, and MoS2 films grown by atomic layer deposition, showing that it can be used across different device structures and fabrication methods. “MoS2 is a promising material for making semiconductor devices, such as transistors smaller and thinner,” said Professor Myung-Soo Kim. “By addressing process contamination that has limited device performance, this work could help advance highly integrated logic and memory devices based on 2D semiconductors.” The study was published online in Small on August 11, 2026. The research was supported by the Ministry of Science and ICT (MSIT), National Research Foundation of Korea (NRF), Institute of Information & Communications Technology Planning & Evaluation (IITP), InnoCORE program, Ministry of Trade, Industry and Energy (MOTIE), and Korea Institute for Advancement of Technology (KIAT). Journal Reference Dahyeon Kim, Yanfeng Zhao, Sungyeon Kim, et al ., “Preventing Plasma-Induced Resist Hardening in Molybdenum Disulfide Transistors via Sacrificial Metal Mask Lithography,” Small, (2026).

Research 2026년 09월 01일 화요일

Rethinking What Matters

《Editor's Note: What does it take to make something work better? The answer may be to pare back what is unnecessary, rethink how existing parts are arranged, find another route around a constraint, or widen the frame of the problem itself. This month's UNIST research offers answers in many forms—from leaner AI systems and redesigned material structures to an unexpected route for electron transfer and a broader view of cancer drug resistance. Some of those answers run counter to what we might expect. 》 Less Can Be Enough “How much does AI really need?” AI has spent years scaling up. But recent UNIST research asks a different question—how much can be taken away while keeping what matters? At ACL 2026, researchers introduced GMoE, an architecture that shares experts across layers rather than repeatedly storing similar ones. It cut model parameters by about 63 percent, from 549 million to 204 million, while average accuracy remained virtually unchanged—39.51 percent, compared with 39.55 percent for the baseline. The next target was data. Presented at ICML 2026, CSOR removes redundant training images while preserving meaningful variation within each identity. Using roughly half the original dataset, models retained more than 95 percent of full-data performance in re-identification (ReID) tasks. A third study moved to hardware. An automated design framework for logic-in-memory (LiM) computing optimized the placement and routing of computing elements, cutting computation cycles by 19.6 percent under area constraints. ■ GMoE—Expert Sharing for Smaller AI Models (ACL 2026) ■ CSOR—Less Training Data for ReID AI (ICML 2026 ) ■ LiM—Smarter Chip Design (IEEE TCAD) Arrangement Matters “In materials, where can matter as much as what.” More iron, less corrosion. Iron (Fe) is one of magnesium's most damaging impurities, yet UNIST researchers produced a Mg alloy containing more than six times as much Fe as ultra-high-purity Mg—and it still corroded more slowly. Instead of removing the impurity, the team added scandium (Sc) to form core–shell particles that isolate Fe-rich regions from the surrounding Mg. The corrosion rate fell from 22.2 to 0.38 millimeters per year, nearly a 60-fold reduction. At the molecular scale, thermal annealing changed the packing of an organic semiconductor, more than tripling its absorption dissymmetry and even reversing its preferred handedness of circularly polarized light (CPL). The resulting near-infrared (NIR) photodetector achieved a dissymmetry factor of 0.1 at 850 nanometers. The scale shifts again in perovskite solar cells (PSCs). The same high-efficiency formulation crystallized differently depending on the buried interface beneath it. Tailoring the chloride chemistry to the inverted architecture produced a device with 26.3 percent efficiency and a fill factor (FF) of up to 86.8 percent. ■ Mg Alloy—Shielding Fe to Slow Corrosion (Science Advances) ■ NIR Photodetector—Turning Molecular Packing (Advanced Science) ■ PSCs—Why Architecture Changes Performance (Joule) Another Way Through “How spin opens a new route for electron transfer.” Conventional energetics suggested that electron transfer should be unfavorable. Yet in manganese (Mn)-doped quantum dots (QDs), spin-exchange interactions enabled transfer more than ten times faster than in undoped QDs. The mechanism could help capture energetic hot electrons before their excess energy dissipates—a longstanding challenge in photocatalysis and solar-energy conversion. ■ Hot Electrons—Spin-Enabled Transfer (Nature Communications) Beyond the Tumor “The cells helping cancer resist treatment.” Some of the cells helping breast cancer resist treatment are not part of the tumor at all. UNIST researchers found that nearby fat cells can become cancer-associated adipocytes, which release complement factor D and activate survival signaling in cancer cells. In mouse models, disrupting this TRAP1-driven communication improved the response to chemotherapy, pointing to surrounding adipocytes as potential therapeutic targets alongside the tumor itself. ■ Breast Cancer—How Nearby Fat Cells Drive Drug Resistance (STTT) Explore the latest issue and follow 『The UNIST Brief』 on LinkedIn to stay updated. Subscribe via LinkedIn

Research 2026년 08월 28일 금요일

New X-Ray Mapping Technique Enables Non-Destructive Analysis of Large-Area Perovskite Solar Cells

Abstract Scaling perovskite solar cells (PSCs) into large-area modules requires precise control of structural uniformity and mechanical integrity. However, scalable deposition often introduces mesoscale heterogeneities, including grain-orientation disorder and lattice-strain gradients, which limit efficiency and stability. Here, we report an intact-film orthogonal two-dimensional X-ray diffraction mapping (2DXDM) technique that enables full-field, quantitative crystallographic analysis of large-area perovskite films without physical sectioning. The method resolves spatial variations in crystallinity, orientation coherence, and lattice strain across complete modules and is validated against conventional sectioned analyzes such as grazing-incidence wide-angle X-ray diffraction (GI-WAXD) and X-ray diffraction (XRD). Using this approach, we compare static spin-coating (SSC) and dynamic spin-casting (DSC). DSC yields more homogeneous films with relaxed lattice stress and controlled solvate evolution, thereby reducing edge defects. As a result, DSC-based modules achieve 23.0% efficiency (22.7% certified) over 86.4 cm2 and retain over 80% of their initial efficiency after 1,000 h of operation. Perovskite solar cells (PSCs) have reached impressive efficiencies at laboratory scale, but maintaining that performance in larger modules remains challenging. As the films grow larger, differences in crystal orientation and internal strain can develop across the surface, creating defects that reduce efficiency and long-term stability. A research team led by Professors Dong-Seok Kim and Jin Young Kim of the School of Energy and Chemical Engineering and Professor Tae Joo Shin of the Graduate School of Semiconductor Materials and Devices Engineering at UNIST, together with Dr. Yun Seop Shin of the Korea Research Institute of Chemical Technology (KRICT), has developed an X-ray technique that maps these structural variations across an intact perovskite film. Called two-dimensional X-ray diffraction mapping (2DXDM), the technique shows how crystallinity, crystal orientation, and residual strain vary across an entity film without damaging it. Conventional methods often examine selected regions, provide averaged measurements, or require samples to be cut into sections. PSCs are made by depositing a liquid precursor onto a surface, where it dries and crystallizes into a light-absorbing layer. Across a large area, differences in drying and crystallization can leave the center and edges with different structural properties. The researchers used 2DXDM to compare two methods for forming large-area films. In static spin-coating (SSC), the precursor solution is applied before the substrate is spun, while dynamic spin-casting (DSC) deposits the solution drop by drop as the substrate rotates. The resulting maps showed that DSC produced more homogeneous films, with more consistent crystal orientation and lower residual strain. Additional X-ray measurements linked this improvement to better control over colon drying and crystal formation, which helped reduce structural defects near the edges. The more uniform films also delivered strong performance at module scale. DSC-based modules reached a power conversion efficiency of 23.0% over an active area of 86.4 cm², with a certified efficiency of 22.7%. Encapsulated modules retained more than 80% of their initial efficiency after 1,000 hours under continuous illumination. “Conventional methods make it difficult to see how structure varies across an entire film, and cutting a sample for analysis can alter the strain already present” said Professor Shin. “With 2DXDM, we can examine the full area without damaging the film and identify where structural differences occur.” Professor Dong-Seok Kim added, “For large-area perovskite films, what matters is structural uniformity across the entire surface, not just at a few individual points. By showing how fabrication conditions affect that uniformity, this approach can help guide the development of more efficient large-area modules.” Dong Shin Kim of the Graduate School of Semiconductor Materials and Devices Engineering and Jae Hwi Lee of the School of Energy and Chemical Engineering at UNIST, served as first authors. The research used the UNIST-PAL 6D beamline at the Pohang Accelerator Laboratory. The findings were published online in Joule on July 23, 2026. The research was supported by the Ministry of Science and ICT (MSIT), Ministry of Education (ME), National Research Foundation of Korea (NRF), Ministry of Trade, Industry and Energy (MOTIE), Korea Institute of Energy Technology Evaluation and Planning (KETEP), Korea Institute for Advancement of Technology (KIAT), and Korea Research Institute of Chemical Technology (KRICT). Journal Reference Dongshin Kim, Jaehwi Lee, Dongmin Lee, et al ., “Intact-film orthogonal 2D X-ray diffraction mapping for crystallographic homogeneity evaluation in perovskite solar modules,” Joule , (2026).

News 2026년 08월 26일 수요일

UNIST Opens Nexus Hall, Connecting Engineering Education with Industry

Students at UNIST will have a new space to learn with advanced technologies—and closer to the industry expertise behind them. Nexus Hall, newly opened in the College of Engineering, brings a wall-sized LED display and integrated audiovisual systems to courses and programs spanning semiconductors, materials, and engineering. Developed with support from Ulsan Metropolitan City, the hall replaces a conventional projector-based classroom into a digital teaching environment built around the large LED display. An electronic lectern and instructor-tracking cameras complete the setup, while the classroom itself has been redesigned for better visibility and comfort. The name Nexus , meaning a point of connection, captures the idea behind the space—bringing education and research into closer contact with industry. The hall will host regular and special courses, along with interdisciplinary semiconductor courses that bring perspectives from outside the university into the classroom. That connection was already evident at the opening ceremony on August 25, 2026. Joo-Young Lee, Executive Vice President of Samsung Electronics, and Se-Yeon Kim, Executive Vice President of SK hynix, spoke with students about shifts in the semiconductor industry, emerging technologies, and the expertise the field increasingly demands. About 80 representatives from UNIST, Ulsan Metropolitan City, and industry attended the opening, including UNIST President Chong Rae Park and Ulsan Mayor Sang-Wook Kim. The new hall also reflects a broader effort by UNIST and Ulsan Metropolitan City to connect education and research with the region's industrial base. UNIST plans to expand ties with semiconductor companies and research institutions, drawing on UNIST's research strengths and Ulsan's manufacturing expertise as the region moves toward more AI-enabled industry. “Nexus Hall will bring education, research, and industry closer together as we prepare students for rapidly changing industries,” said UNIST President Chong Rae Park. “By connecting academic training more closely with industry, we hope to develop students who can work across disciplines and contribute to industrial innovation in Ulsan.” “Semiconductors underpin advances in artificial intelligence (AI), batteries, future mobility, and other emerging industries,” said Ulsan Mayor Sang Wook Kim. “We will continue working with UNIST and other universities in the region to develop the expertise companies need and create more opportunities for young people to build their careers in Ulsan.”

Research 2026년 08월 25일 화요일

New Strategy Shields Magnesium from Impurity-Driven Corrosion

Abstract Magnesium (Mg) alloys offer high weight-saving potential for transportation technologies; However, their use remains constrained by poor corrosion resistance, which is strongly dependent on alloy purity. The presence of impurities, such as iron (Fe), severely degrades the corrosion resistance of Mg alloys. Herein, we present an alloy design strategy that substantially improves the corrosion resistance, even when using low-purity Mg. Our method produces core-shell particles, where an Fe-rich core is encapsulated by an Fe-depleted shell embedded in the Mg matrix. This shell acts as a local microscavenger that isolates the core and suppresses impurity-triggered corrosion, resulting in corrosion resistance achievable only when using ultrahigh-purity Mg. This approach provides a practical pathway for the development of high-performance Mg alloys without relying on costly purification. Magnesium (Mg) is prized for its exceptionally low weight, but its tendency to corrode has limited its wider use in cars, aircraft, drones, and other applications where lighter materials could offer significant advantages. Even trace amounts of iron (Fe) can accelerate that corrosion, making material purity a critical—and costly—part of producing durable Mg alloys. Professor Sung Soo Park and his research team in the Department of Materials Science and Engineering at UNIST approached the problem differently. Rather than removing Fe impurities, they designed the alloy to isolate them and limit their ability to trigger corrosion. The resulting material encloses Fe-rich regions within specially formed particles and maintains strong corrosion resistance despite being made from lower-purity Mg. The researchers achieved this by adding a small amount of scandium (Sc) to a magnesium-aluminum (Mg-AI) alloy. As the alloy solidifies, Fe becomes concentrated at the center of microscopic particles, surrounded by an outer layer containing very little Fe. This core–shell structure separates the Fe-rich center from the surrounding Mg, preventing it from readily initiating corrosion. The team identified scandium through theoretical calculations that screened a range of elements for their ability to produce the desired structure. Rather than reducing the total amount of iron, the strategy controls how the impurity is distributed within the alloy. The difference was clear in saltwater tests. After three days of immersion, the Mg-AI alloy without scandium showed severe corrosion, while the scandium-containing alloy largely retained its original form. Its corrosion rate fell from 22.2 millimeters per year to 0.38 millimeters per year, nearly a 60-fold reduction. The approach also proved effective in a commercial Mg alloy. Adding only a trace amount of scandium reduced its corrosion rate to about one-seventh that of the original alloy, suggesting that the strategy could extend beyond the experimental material. Notably, the newly designed alloy contained more than six times as much Fe as an ultrahigh-purity Mg alloy, yet corroded more slowly. The result shows that corrosion resistance depends not only on how much Fe is present, but also on how that Fe is distributed within the material. “Mg alloys have traditionally required expensive, high-purity raw materials with extremely low Fe content to achieve strong corrosion resistance,” said Professor Park. “Our findings show that controlling how Fe is distributed within the alloy offers another way to address the problem.” He further added, “Reducing the need for ultrahigh-purity magnesium could lower material costs and help expand the practical use of lightweight magnesium alloys.” The findings were published online in Science Advances on July 23. The research was supported by the Ministry of Science and ICT (MSIT) and the National Research Foundation of Korea (NRF), among other funding sources. Journal Reference Jeong-Ki Kim, Jaeho Kwon, Du-Won Min, et al ., “Core-shell particle engineering overturns conventional purity-corrosion dependence in Mg alloys,” Sci. Adv., (2026).

Research 2026년 08월 01일 토요일

Beyond the Obvious

《Editor's Note: The biggest scientific advances do not always come from discovering something new. Sometimes, they begin by seeing familiar problems in a new light. This month's stories invite us to look beyond the obvious. Across artificial intelligence, semiconductor materials, nanotechnology, and biomedical science, UNIST researchers examined assumptions, structures, and interactions that can easily go unnoticed—but often determine how a system behaves. Their findings show how a deeper understanding of what is already there can open new directions for discovery.》 Questioning Assumptions “The first answer is not always the right one.” Scientific discovery often begins by asking whether the original question was complete. Several AI studies featured this month did just that, revisiting assumptions about how machines learn, forget, reason, and communicate. In federated learning, researchers found that differences in camera viewpoints—not only privacy constraints or data distribution—can significantly affect how well AI models learn together. Another team showed that machine unlearning involves more than simply removing data: forgetting can unintentionally alter knowledge that should remain. Elsewhere, a new communication framework showed that effective cooperation among AI agents depends less on exchanging more information than on exchanging the right information. Other studies reconsidered how AI systems reason across multiple views of the same scene and explored how quantum computing could reduce the cost of training robust AI models. Different problems, but a common starting point: questioning the assumptions built into them. Together, these studies point to a simple lesson: better answers often begin with better questions. ■ Rethinking Federated Learning: Camera Viewpoints Matter (CVPR 2026) ■ Making AI Forget—Without Losing What Matters (ICML 2026 ) ■ Smarter Communication for Collaborative AI (ICML 2026) ■ Rethinking Multiview Reasoning (ICML 2026) ■ Quantum Algorithm Cuts the Cost of Training Robust AI (ICML 2026) Looking Beneath the Surface “The smallest details often hold the biggest clues.” Across materials science, biology, nanotechnology, and semiconductor engineering, UNIST researchers examined structures and interactions that are easy to miss but can have an outsized influence on how materials, devices, and biological systems behave. In semiconductor research, the spacing between neighboring atoms emerged as a critical factor in controlling material properties and device performance. At the nanoscale, researchers examined how the surface chemistry of quantum dots influences their behavior in imaging. Another study turned to microscopic wrinkles, showing how their geometry can reshape optical properties. The same attention to underlying mechanisms extended to biology, where researchers found that familiar forms of cell death do not always follow the pathways scientists expect. Together, these studies show how seemingly minor details—from atomic spacing and surface chemistry to microscopic geometry and cellular mechanisms—can fundamentally change our understanding of a system. Sometimes, the most consequential discoveries begin with something that was there all along, waiting to be examined more closely. ■ Atomic Precision for Better Semiconductors (Chem. Mater., 2026) ■ A New Perspective on QD Imaging (Nano Converg., 2026) ■ Wrinkles that Reshape Photonics (Adv. Funct. Mater., 2026) ■ When Cell Death Follows Different Rules (Cell Death Differ., 2026) Across very different fields, these studies share a common instinct: question the assumption, examine the detail, and look again. What appears familiar can still hold unanswered questions. Looking beyond the obvious is not simply how these discoveries were made. It is how scientific discovery moves forward. Explore the latest issue and follow 『The UNIST Brief』 on LinkedIn to stay updated. Subscribe via LinkedIn

Research 2026년 07월 29일 수요일

Specific Atomic Distances Shape Defect Behavior in Oxide Semiconductors

Abstract Oxygen vacuums (VO) critically influence the electrical performance and reliability of amorphous oxide semiconductor (AOS) devices, including indium–gallium–zinc oxide (IGZO) thin-film transistors (TFTs). Using first-principles density functional theory and configuration-coordinate analysis, we elucidate a unified mechanism connecting the contrasting behaviors of VO under strain versus annealing. We demonstrate that both mechanical strain and annealing-induced structural relaxation modulate the energetic position and localization character of VO states by altering specific interatomic distances. Compressive strain shortens key metal–metal separations, thereby stabilizing bonding-like localized states, lowering their formation energy, and driving a delocalized-to-localized transition; conversely, tensile strain induces the opposite trend. Along the structural-relaxation pathway, the defect level shifts upward toward the conduction band minimum as critical distances increase, promoting delocalization. Ab initio molecular dynamics simulations further corroborate that higher thermal budgets facilitate this relaxation, thereby enhancing donor activation. Crucially, we resolve the prevailing apparent strain–annealing densification inconsistency: annealing-induced delocalization arises not from increased mass density (as in compressive strain), but specifically from structural relaxation that expands critical interatomic distances and minimizes screened ion–ion repulsion. These findings provide a rigorous atomistic framework for manipulating defect states via strain engineering and thermal processing, offering precise guidelines for optimizing the stability and performance of next-generation AOS electronics. A new study from UNIST explains what determines the behavior of oxygen vacuums—tiny defects that strongly influence how oxide semiconductors perform. The researchers found that the key is not the material's overall atomic density, as previously thought, but the spacing between neighboring atoms around the defect. The findings offer new guidance for designing oxide semiconductors used in displays and next-generation memory devices. The study was led by Professor Changwook Jeong of the Graduate School of Semiconductor Materials and Devices Engineering, who used theoretical calculations to uncover how local atomic arrangements control the electrical properties of oxygen vacuum. Oxygen semiconductors, such as indium–gallium–zinc oxide (IGZO) are widely used in thin-film transistors for smartphones and television displays because they can be processed at relatively low temperatures. During fabrication, however, oxygen vacuums naturally form within the material. These defects can change how electricity flows through a device, affecting its operating voltage, performance, and long-term stability. The team found that even small changes in the spacing between nearby metal atoms determine whether electrons remain trapped around an oxygen vacancy or move freely through the material. When those atoms move closer together, the electrons stay localized near the defect. As the distance increases, the electrons spread more easily, making electrical conduction more favorable. The findings also resolve a long-standing question in oxide semiconductor research. Heat treatment and mechanical compression both make the material denser, yet previous studies showed that they have opposite effects on oxygen vacuums. The team demonstrated that density itself is not the deciding factor. Instead, each process changes the local arrangement of atoms in a different way, leading to different electrical behavior. To reach these conclusions, the researchers combined density functional theory, configuration-coordinate analysis, and ab initio molecular dynamics simulations. Together, the calculations revealed a single mechanism that explains how both heat treatment and mechanical strain influence oxygen vacuums, providing a theoretical framework for optimizing oxide semiconductor processing. “Oxygen vacuums are unavoidable in oxide semiconductors, but this study shows that their electrical behavior can be controlled through processing conditions,” said Professor Jeong. “By tailoring heat treatment and mechanical stress, it should be possible to optimize threshold voltage, switching characteristics, and device reliability at the same time.” The findings were published in Chemistry of Materials on June 23, 2026. The research was supported by the Nano & Material Technology Development Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (MSIT). Journal Reference Hyeongjun Jang, Yoonju Park, Beomjin Park, et al., “A Unified Mechanism for Strain- and Anneal-Induced Oxygen-Vacancy Behavior in Oxide Semiconductors,” Chem. Mater., (2026).

Research 2026년 07월 22일 수요일

New Wrinkle Architecture Broadens Optical Responses for Advanced Security Films

Abstract Wrinkle-based diffraction gratings offer a scalable route to pigment-free structural coloration, yet most platforms are limited by globally aligned, linear wrinkles that provide limited spatial programmability and narrow angular selectivity. Here, we report geometrically programmed wrinkle architectonics in a UV-curable chitosan (UVCC)/polydimethylsiloxane (PDMS) bilayer, where lithography-defined, “geometric voids” serve as boundary constraints and stress concentrators to deterministically steer wrinkle trajectories during mechanical deformation. Simple geometric primitives effectively reshape the local stress field through geometrically incompatible confinement, transforming 1D gratings into shape-specific, spatially bifurcated domains characterized by curvilinear orientation and straight-wrinkle fields. We quantify these trajectory fields using the curvature metric and map critical design levers, such as inter-pattern spacing, UVCC thickness, and pattern asymmetry, that modulate curvature magnitude and steering range without altering diffraction periodicity. Circular perimeters sustain extended semi-circular trajectories, whereas polygonal vertices concentrate stress to induce aggressive local curvature. This programmed orientation dramatically amplifies angular dispersion: symmetric circular arrays achieve peak viewing-angle responsivity nearly three times higher than that of unpatterned thin films. A macaw security motif confirms wide-angle azimuthal readability and the formation of device-unique optical fingerprints for anti-counterfeiting. This work transforms a ubiquitous mechanical instability into a geometry-addressable photonic platform for high-level authentication and advanced displays. Hidden optical images that appear only when a transparent film is bent could provide a new generation of anti-counterfeiting technologies. Researchers at UNIST have demonstrated a strategy for programming the microscopic wrinkle patterns responsible for structural color, enabling optical films with enhanced viewing-angle sensitivity and unique optical fingerprints. Led by Professor Taesung Kim of the Department of Mechanical Engineering, the researchers discovered that simple geometric patterns can precisely control how microscopic wrinkles form as the film bends. By reshaping local mechanical stresses, the patterned boundaries guide wrinkle growth into both straight and curved domains while preserving the regular spacing responsible for structural color. This independent control over wrinkle orientation expands the film's optical capabilities. The enhanced wrinkle architecture translated directly into a broader optical response. The engineered films required only seven degrees of viewing-angle change to display the full visible color spectrum, compared with approximately thirty degrees for conventional wrinkle-based films. Distinct color changes also appeared with angular shifts as small as one degree, allowing substantially more optical information to be encoded within the same viewing range. To demonstrate these capabilities, the team fabricated a transparent security film featuring a hidden macaw image that appeared only when the film was bent. Unlike conventional wrinkle-based security films, which are visible only over a narrow range of viewing angles, the new design maintains clear image visibility and vivid structural colors across viewing angles from 0° to 90°. Each film also developed subtle variations in wrinkle branching, creating device-specific optical fingerprints that provide an additional layer of authentication beyond the visible security image. The films also showed excellent mechanical durability, maintaining stable wrinkle patterns and optical performance after 500 repeated bending cycles. “Instead of treating wrinkles as an unavoidable mechanical instability, we showed that they can be programmed through geometric design,” said Professor Kim. “By controlling wrinkle orientation while preserving wrinkle periodicity, we significantly broadened the optical response of wrinkle-based structural color films.” He added, "The approach could be applied to anti-counterfeiting technologies for banknotes, identification cards, luxury goods, and pharmaceutical packaging, while also providing a versatile platform for optical sensors and flexible display technologies." The findings were published in Advanced Functional Materials on June 25, 2026. Dr. Kaliannan Thiyagarajan and Sungjoon Ji from UNIST served as co-first authors of the study. The research was supported by the National Research Foundation of Korea (NRF) and UNIST. Journal Reference Kaliannan Thiyagarajan, Sungjoon Ji, Jiseok Han, et al ., “Geometrically Programmed Wrinkle Architectonics for High Angle-Dependent Structural Coloration,” Adv. Funct. Mater. , (2026).

News 2026년 07월 16일 목요일

UNIST Secures Five National Basic Research Laboratory Grants

UNIST has secured five projects under the national 2026 Basic Research Laboratory (BRL) Project , earning KRW 7.5 billion in government funding over the next three years. The projects span life sciences, physics, materials science, and biomedical engineering, bringing together interdisciplinary teams to address fundamental scientific challenges. Administered by the Ministry of Science and ICT (MSIT), the BRL Program supports collaborative basic research that benefits from the combined expertise of multiple investigators. Each selected project will receive KRW 1.5 billion over three years. Three of the five newly funded projects are led by faculty in the Department of Biological Sciences—an exceptional outcome for a single department. Professor Byoung Heon Kang will lead a project investigating how mitochondrial reprogramming within the tumor microenvironment drives cancer progression and therapeutic resistance. Joining the project are Professors Sebyung Kang, Young Chan Chae, and Sung-Min Hwang from the Department of Biological Sciences, whose expertise spans cancer metabolism, cell signaling, and tumor biology. Professor Sung-ho Park will direct the Center for Tissue-Resident Macrophage Homeostasis, examining how tissue-resident macrophages maintain immune balance and how their functions become disrupted during infection and aging. Professors Sangjoon Lee and Jung-Seok Kim from the Department of Biological Sciences will participate as co-investigators. Professor Jayil Lee will lead a project exploring how the three-dimensional organization of chromatin regulates gene expression. The research will investigate how distant regulatory elements interact with target genes to control transcription, integrating expertise in genome architecture, molecular imaging, and chemical biology through collaborations with Professor Hajin Kim from the Department of Biomedical Engineering, Professor Duyoung Min from the Department of Chemistry, and Professor Inwha Baek of Kyung Hee University. Professor Chaenyung Cha will establish the In Situ Programmable Bioprinting Laboratory for Spinal Cord Regeneration, developing bioprinting technologies that precisely position biomaterials and signaling molecules according to the biological environment of injured spinal tissue. The project brings together Professors Jeong Beom Kim and Jinmyoung Joo from the Department of Biomedical Engineering, and Professor Seong Geun Yoon of Ulsan University Hospital, combining expertise in biomaterials, tissue engineering, and clinical medicine. Professor Jung-Woo Yoo will lead a multidisciplinary team investigating spin structures and spin dynamics in quantum materials. Working with Professors Ho-Seop Jin, Yoonseok Oh, and Seokhyung Lee from the Department of Physics, the researchers aim to establish a unified understanding of spatiotemporal spin correlations, providing a scientific foundation for future quantum devices and spintronic technologies. Together, the five projects reflect UNIST's interdisciplinary research model, bringing together scientists from multiple fields to tackle complex questions in fundamental science. “The selection of these five BRL projects reflects the strength of UNIST's basic research and its collaborative research environment,” said KwanMyung Kim, Dean for Research Affairs at UNIST. “We will continue to strengthen long-term fundamental research and interdisciplinary collaboration, expanding the scientific foundations for future advances in biotechnology, quantum science, and advanced materials.”

Research 2026년 07월 02일 목요일

New Semiconductor Device Brings Communication and AI Computing onto a Single Chip

Abstract Next-generation 6G communication systems necessitate hardware that simultaneously manages high-frequency signal routing and massive matrix-level computations under extreme constraints. However, conventional digital architectures suffer from high power dissipation and area overhead. Here, we report an oxidized molybdenum disulfide (MoS2)-based memristive platform that integrates nonvolatile radio-frequency (RF) switching and energy-efficient vector–matrix multiplication. By implementing a controlled thermal oxidation process, we achieve stable resistive switching with low switching energy and zero-static power consumption, while maintaining a high cutoff frequency of 33.2 THz, outperforming existing phase-change and microelectromechanical systems (MEMS) technologies. Using system-level simulations, we demonstrate the robustness of this hardware through successful 1024-quadrature amplitude modulation (1024-QAM) demodulation, spectral analysis, and multiple-input multiple-output (MIMO) signal reconstruction, even when accounting for intrinsic device non-idealities. This monolithic integration of high-frequency switching and analog computing provides a scalable solution for energy-efficient deployment of intelligent wireless systems. Future 6G networks and satellite communication systems will require hardware that can process growing amounts of data while operating under strict power and space constraints. Professor Myungsoo Kim and his research team from the Department of Electrical Engineering at UNIST introduced a new semiconductor device that combines high-frequency signal switching and computation on a single platform, offering a more compact and energy-efficient approach to next-generation wireless systems. At the heart of the platform is a multifunctional memristor based on oxidized molybdenum disulfide (MoS2), a two-dimensional semiconductor. The device functions as both a radio-frequency (RF) switch and hardware for in-memory matrix operations, bringing communication and computation onto a single chip. Conventional communication systems typically separate these functions, requiring signals to move between switching circuits and processors. This data movement increases power consumption, processing delays, and chip size. By integrating both functions into a single device, the new platform simplifies signal processing while improving energy efficiency. The memristor also operates without standby power. Once switched between its ON and OFF states, it retains that state even after power is removed, making it particularly well suited to energy-constrained applications such as satellite communications and future 6G infrastructure. The device demonstrated a switching energy of just 140 picojoules per operation and switching power below one milliwatt. It maintained stable operation for more than 40,000 seconds and over 1,000 switching cycles, while achieving a calculated cutoff frequency of 33.2 THz. Experimental measurements verified high-frequency switching up to 67 GHz. To evaluate its computing capability, the researchers performed system-level simulations of wireless communication tasks. The device successfully carried out 1024-quadrature amplitude modulation (1024-QAM) demodulation and multiple-input multiple-output (MIMO) signal reconstruction, demonstrating that a single hardware platform can efficiently support both communication and signal processing. "Commercial RF switches continuously consume standby power and often suffer signal loss at high frequencies," said Juhyo Son, the study's first author. "Our device addresses these limitations while remaining competitive with existing phase-change memory and MEMS technologies in energy efficiency, operating speed, and scalability." Professor Kim added, "Our study demonstrates that oxidized MoS₂ memristors can function not only as high-performance RF switches but also as hardware for the in-memory matrix operations required for next-generation wireless communications. By combining nonvolatile operation, low power consumption, and high-frequency performance, this platform could contribute to more compact and energy-efficient systems for satellite communications, radar, defense electronics, and future 6G RF front ends." The research was supported by the National Research Foundation of Korea (NRF) through the Ministry of Science and ICT (MSIT), the Institute for Information & Communications Technology Planning & Evaluation (IITP), the Space-K BIG Project, and a regional talent development program. The findings were published online in Advanced Functional Materials on June 6, 2026. Journal Reference Juho Son, Changwoo Pyo, Sungmoon Park, et al., “ Oxidized MoS2-Based Multifunctional Memristive Hardware for Energy-Efficient mmWave Signal Processing and In-Memory Matrix Multiplication ,” Adv. Funct. Mater., (2026).