Research Team Led by Professor Kwon Hyuk-jin at National Pukyong University Develops Low-Power Printed Flexible Transistor Electronic Device

Research Team of Professors Im Bo-gyu from Chungbuk National University, Kim Se-hyun from Konkuk University, and Lee Seung-woo from Yeungnam University

On the 15th, Pukyong National University (President Sang-Hoon Bae) announced that the research team led by Professor Hyuk-Jin Kwon (majoring in Industrial Chemistry) has developed a polyimide-based gate insulator technology, which is gaining attention as a core material for next-generation flexible electronic devices.

The joint research team, including Professor Hyuk-Jin Kwon, Professor Bo-Gyu Lim from Chungbuk National University (Department of Industrial Chemistry), Professor Se-Hyun Kim from Konkuk University (Department of Chemical Engineering), and Professor Seung-Woo Lee from Yeungnam University (Department of Chemical Engineering), published their research results in an international journal in the field of materials last October.

Printed electronic devices are made by dissolving materials in solvents and printing electronic devices using an inkjet printer. Compared to conventional manufacturing methods that use expensive vacuum equipment, this method is cheaper and allows the production of electronic devices at low temperatures. However, due to the laminated structure of the printing method, materials are damaged during the manufacturing process, making it difficult to produce complete devices through the printing process.

The joint research team developed a new material called "methacryloyl polyimide (PI-MA)" that simultaneously realizes photopatterning and high dielectric constant (High-k) properties, and succeeded in implementing low-power flexible transistor electronic devices using printing methods.

By utilizing this technology, electronic devices can be manufactured by printing semiconductor and insulator solutions using an inkjet printer. The joint research team overcame these issues by applying cross-linking technology during the printing process. Cross-linking fixes the connections between molecules firmly, improving the thermal and chemical stability of the material.

To this end, the research team developed a fluorine-based methacryloyl polyimide insulator capable of photochemical cross-linking, and by introducing fluorine into the polyimide molecules, they secured a dielectric constant of 8 at 1 kHz. This is a significantly improved value compared to the dielectric constants of previously reported polyimides.

Additionally, the developed polyimide exhibits low leakage current values even without heat treatment processes, making it suitable as an insulator for transistors. Using the developed insulator, transistors were manufactured through an all-printing process, and high electrical characteristics of the transistors were observed at low voltages below 5V, with successful implementation of logic circuits with excellent performance.

Research image of Professor Hyukjin Kwon. Image of a transistor printed with a PI-MA layer and a schematic diagram of the photopolymerization process, (center) schematic diagram of flexible transistor electronic device fabrication printed with a PI-MA layer and photo of a device processed with a dedicated solution, (bottom) photo of a flexible device and image of a circuit device processed with a dedicated solution

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