Research

[Science publication; 20× higher deep-UV emission efficiency than conventional materials; 

expected to enable next-generation hygiene technologies to help curb infectious disease spread]

A Korean research team has developed a new material that emits high-efficiency light in the deep-ultraviolet (DUV) range—an area long considered virtually impossible to realize with conventional semiconductor technologies.

The Ministry of Science and ICT(MSIT) announced that a joint research team led by Professor Jonghwan Kim and Professor Moon-Ho Jo of POSTECH successfully implemented a new type of quantum-well structure based on a van der Waals semiconductor material, achieving 20 times higher DUV emission efficiency than existing materials.

This achievement, supported by MSIT’s Basic Research Program (Mid-Career Researcher Program) and the Institute for Basic Science (IBS) Support Program, was published in the world-renowned journal Science on March 20.

Semiconductor light sources in the visible range have driven advances across industries, including white LED lighting, displays, and laser sources. In recent years, development has expanded toward ultraviolet (UV) LEDs, which have shorter wavelengths and higher energy than visible light. In particular, since the COVID-19 pandemic, interest has surged in DUV light sources capable of effectively inactivating bacteria and viruses.

Conventional UV LEDs primarily use gallium nitride (GaN)-based semiconductors. By replacing part of gallium (Ga) with aluminum (Al) to form aluminum gallium nitride (AlGaN), the emission wavelength can be tuned into the DUV region. However, once the wavelength reaches 200–240 nm, the light-source efficiency drops sharply to below 1%, leaving this range as a technologically challenging and largely unexplored frontier.

To overcome this limitation, the team developed a new LED nanomaterial using a van der Waals layered semiconductor. In van der Waals layered structures, atoms are strongly bonded within each atomic layer, while adjacent layers are held together by relatively weak van der Waals forces, allowing the layers to be separated and re-stacked with relative ease.

Boron nitride (BN) is a semiconductor material in which atomic layers are stacked via van der Waals forces. The team discovered that when BN layers are twisted and stacked, a new kind of quantum-well structure forms that can strongly confine electrons. They named this structure the “moiré quantum well.” By confining electrons within a nanometer-scale region, the moiré quantum well is highly advantageous for efficient light emission in the DUV range, demonstrating more than 20× higher emission efficiency compared to conventional AlGaN semiconductors.

Until now, quantum phenomena in van der Waals materials have largely been studied in atomically thin film structures such as graphene. This work, however, opens new possibilities by showing that a unique two-dimensional quantum-well structure can be realized simply by twisting and stacking a three-dimensional boron nitride crystal.

The achievement also holds significant promise for public health and environmental hygiene applications. Among DUV wavelengths known for strong disinfection performance, the currently commercialized 260 nm band can cause serious health issues if human skin or eyes are exposed, limiting its use. By contrast, DUV light in the 200–230 nm band is known to be relatively safer for humans because it cannot penetrate the outermost layer of skin (the stratum corneum).

By overcoming the long-standing challenge of achieving high-efficiency emission in this wavelength band, the commercialization of 200–230 nm DUV LEDs could enable next-generation hygiene technologies that continuously disinfect air and surfaces in high-traffic indoor spaces—such as hospitals, schools, and public transportation—while minimizing potential risks associated with existing UV-based disinfection.

Professor Jonghwan Kim said, “This is a conceptual shift that extends the unique moiré quantum physics observed in van der Waals materials from two-dimensional systems to three-dimensional materials,” adding, “This research will serve as a starting point for designing new quantum materials and developing next-generation optoelectronic devices.”

Hyuk Chae Koo, First Vice Minister of the Ministry of Science and ICT, stated, “Professor Jonghwan Kim is a researcher who has steadily pursued long-term research in a single field over the past decade through MSIT’s basic research program,” adding, “We will continue to provide full support to create an environment where researchers can immerse themselves in long-term research without being overly pressured by short-term outcomes.”

Going forward, the team plans to expand this work toward developing high-efficiency DUV light-source devices and exploring a wide range of applications in next-generation quantum photonic devices based on this technology.

▶️ DOI: science.org/doi/10.1126/science.aeb2095