A research team led by Professor Kang Bosoek of Sungkyunkwan University has developed two molecular design technologies to increase the electrical conductivity of organic electronic materials, which are lightweight and flexible components used in sensors, wearable electronics, and next-generation displays.
Improving Charge Generation and Transport
The researchers addressed two primary challenges for the practical use of organic semiconductors: generating sufficient charge and ensuring that charge moves rapidly through the material. The findings were published in Nature Communications and the Journal of the American Chemical Society, with the latter also selecting the paper as a Cover Article.
In the first study, the team created a molecular-level design to increase charge carriers within a polymer. By covalently attaching the polar molecule aminoalkylsilane to the n-type conducting polymer PBFDO, the team increased electron concentration. Because the bonded polar molecules aligned in a consistent direction, they induced electron generation without relying heavily on external dopants. This resulted in a thin film with electrical conductivity exceeding 3,000 S cm−1 and a doping efficiency of approximately 1.79 free electrons per polymer repeat unit, raising the doping limit to a near-theoretical level.
The second study focused on the charge transport pathway. The team created a molecular bridge
structure by applying a thin coating of conducting polymer onto a thin film of a two-dimensional covalent organic framework (2D COF). According to the researchers, this structure links separated COF crystals to bridge pathways broken by the polycrystalline structure, allowing charge to move more smoothly.
Performance Results and Applications
The resulting COF–conducting polymer heterostructure thin film demonstrated an electrical conductivity improvement of approximately 10 times compared to a single conducting polymer thin film and 109 times compared to a single COF thin film. The team successfully fabricated a uniform thin film on a 2-inch wafer scale. When used in a nitrogen dioxide (NO2) gas sensor, the film responded in approximately 20 seconds and detected concentrations as low as 74 ppb.
Professor Kang Bosoek stated that the research addressed charge generation and charge transport at the molecular level. He added that the team plans to develop heterojunction structures with various semiconductor materials to create high-performance electronic devices. Additionally, the team is exploring the use of charge states as a new information-processing function.
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