KAIST develops next-generation 2D material that retains performance when stacked

South Korean researchers have proposed a new design principle that can realize, in actual materials, the intrinsic electronic structure of two-dimensional conductive metal-organic frameworks — a structure that had previously existed only in theory. The advance is expected to accelerate the practical application of next-generation electronic devices and quantum materials.

KAIST announced Monday that a research team led by Professor Park Sun-a of the Department of Chemistry, working with Professor Christopher Hendon of the University of Oregon, has developed a new two-dimensional conductive metal-organic framework (MOF) that maintains high electrical conductivity while minimizing interlayer interference.

Two-dimensional materials are considered leading candidates for next-generation semiconductors and quantum materials because their atom-thin structure allows electrons to move rapidly. Stacking multiple layers, however, causes interlayer interactions that impede electron movement and degrade performance.

To overcome this problem, the research team focused on the angle at which layers are arranged relative to one another. The newly designed molecular structure ensures that each layer sits at a fixed angle when stacked, minimizing direct face-to-face contact between layers — much like slightly fanning a deck of cards so the sheets do not fully overlap and stick together. As a result, interlayer interactions are reduced and electrons can move more freely. To achieve this structure, the team designed triptycene-based molecules and used them to synthesize the new two-dimensional conductive MOF material.

The newly developed material preserves an electronic structure similar to that of a single layer even when multiple layers are stacked. It retained a distinctive electronic structure — the Dirac band structure of a kagome lattice — that allows electrons to move quickly and efficiently. This structure lets electrons travel as if on a highway, free of complex obstacles, making it well suited for achieving high electrical conductivity. The result demonstrates that an electronic structure previously thought achievable only in a single layer can in fact be maintained in a bulk material composed of multiple stacked layers.

The material exhibited electrical conductivity of 0.58 S/cm without any additional doping — the process of introducing impurities to enhance electrical properties. This confirmed that excellent electrical performance can be achieved while reducing interlayer interference.

The research is significant in that it resolves a longstanding challenge in two-dimensional materials: performance degradation upon stacking. By demonstrating that superior electronic properties once thought possible only in a single layer can be realized in actual materials, the findings are expected to mark an important turning point in bridging fundamental research and practical technology.

"We plan to explore potential applications in sensors and energy storage that make use of conductive porous materials," Professor Park said. "Our long-term goal is to exfoliate the material down to a single layer or a few layers and apply it as a platform for next-generation electronic devices and quantum materials."

The research, supported by the National Research Foundation of Korea, was published in the Journal of the American Chemical Society on April 8.