The Michigan Engineer News Center

Seunghyun Lee takes the gold for all-graphene flexible and transparent circuit

Lee believes that graphene will play a pivotal role in realizing high speed, mechanically compliant, and transparent electronic systems in the future.| Short Read
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IMAGE:  Seunghyun Lee holding his Gold Award from the Materials Research Society

Seunghyun Lee. doctoral candidate in the electrical engineering program, was honored with a Gold Graduate Student Award at the Fall meeting of the Material Research Society for his research on flexible transparent circuits made entirely from graphene. He demonstrated for the first time flexible and transparent all-graphene circuits for quaternary digital modulations that can encode two bits of information per symbol.

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IMAGE:  Seunghyun Lee's all-graphene circuit

“High speed circuits are needed for portable flexible electronics that rely on wireless communication,” explains Lee. “However, developing a wireless communication system with conventional flexible materials such as organic polymers, amorphous silicon, or oxide-based thin film transistors is still a challenge due to their limited carrier mobilities.”

High carrier mobility is needed to create the high speed circuits required for wireless communication, leading Lee and his group to investigate graphene.

“Graphene,” stated Lee, “is an ideal material for flexible high speed communication systems due to its high carrier mobility, ambipolarity, transparency, and mechanical flexibility. The monolithic structure allows unprecedented mechanical flexibility and near-complete transparency(~95%), while the ambipolarity allows for drastically reduced the circuit complexity compared to silicon-based modulators.”

Lee believes that graphene will play a pivotal role in realizing high speed, mechanically compliant, and transparent electronic systems in the near future. Some of the applications envisioned by Lee include smart electronics, sensor networks, flexible displays, biomedical electronics, and wearable electronics.

Lee’s winning presentation was based on the conference paper, “An All-Graphene Flexible and Transparent Circuit for Quaternary Digital Modulation,” co-authored by fellow graduate students Kyunghoon Lee, Chang-Hua Liu, Girish S. Kulkarni, and his advisor, Prof. Zhaohui Zhong.

He fabricated the device in the Lurie Nanofabrication Facility at the University of Michigan. The research was funded in part by the National Science Foundation Scalable Nanomanufacturing Program.

About the Award


The MRS Graduate Student Awards honor and encourage graduate students whose academic achievements and current materials research display a high level of excellence and distinction. MRS recognizes students of exceptional ability who show promise for significant future achievement in materials research.

Mr. Lee was selected as one of seven Gold Award winners out of 242 candidates.

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The electrons absorb laser light and set up “momentum combs” (the hills) spanning the energy valleys within the material (the red line). When the electrons have an energy allowed by the quantum mechanical structure of the material—and also touch the edge of the valley—they emit light. This is why some teeth of the combs are bright and some are dark. By measuring the emitted light and precisely locating its source, the research mapped out the energy valleys in a 2D crystal of tungsten diselenide. Credit: Markus Borsch, Quantum Science Theory Lab, University of Michigan.

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