△From left, Dr. Jeonghoon Lee (first author, Northwestern University), Prof. Hoonkyung Lee(corresponding author, Konkuk University), Prof. Wihyung Lee (corresponding author, Konkuk University)

Prof. Wihyung Lee (Division of Chemical Engineering, corresponding author), Prof. Hoonkyung Lee (Department of Physics, corresponding author) of Konkuk University, and Dr. Jeonghoon Lee (Department of Materials Science and Engineering, first author) of Northwestern University have identified new soluble acenes and optimizing their solution processing. The paper was published on September 30 in Small (IF = 13.0), a leading nanoscience journal.

The demand for flexible electronics, such as wearable devices and flexible displays, is rapidly increasing in the era of the Internet of Things (IoT). These electronic devices are fabricated on flexible substrates instead of traditional rigid substrates. As a result, they must be able to withstand physical deformation while maintaining performance. The need for solution process technologies that can be processed at low temperatures and applied to large-area substrates is increasing.

In this study, the team analyzed process variables such as spin-coating time to determine the optimal process conditions for low molecular weight organic semiconductors and polymer blend systems. It is essential to recognize that the performance of organic semiconductor-based electronics could be significantly influenced by the spin-coating processing condition. The results showed that the optimal spin-coating time allows the organic semiconductor to achieve the highest crystallinity and maximize electrical performance.

The team analyzed how the molecular structure of the organic semiconductor affected various factors such as the concentration, viscosity, and crystallinity of the solution. Specifically, they found that how the organic semiconductor interacts with the solvent remaining after deposition plays a critical role in crystallization. This provided important clues to the optimal process conditions for producing high-performance organic semiconductor films.

The team of Hoonkyung Lee at Konkuk University revealed the correlation between the electrical performance and molecular structure of organic semiconductor films by investigating the intermolecular interactions through density functional theory (DFT) calculations. These results are believed to contribute to the commercialization of organic electronic devices.

The research is considered an important advance in next-generation flexible electronics. It provides a strategy for large-area semiconductor thin-film formation, enabling high-performance organic thin-film transistors. "This study enhances our understanding of organic semiconductor processing technology and will play an important role in the commercialization of flexible electronic devices," said Prof. Wihyung Lee of Konkuk University, corresponding author of the study.

The first author, Dr. Jeonghoon Lee, received his bachelor's and master's degrees from the Department of Organic Nanosystems Engineering at Konkuk University and his Ph.D. from the Department of Materials Science & Engineering at Seoul National University. He is currently a postdoctoral fellow at Northwestern University.

Research supported by Ministry of Science and ICT and Ministry of Trade, Industry and Energy.

※Paper title:“Crystal Engineering Under Residual Solvent Evaporation: A Journey Into Crystallization Chronicle of Soluble Acenes”

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