Prof. Dong Sung Kim Demonstrates Transparent and Flexible Triboelectric Nanogenerator Using Thermal Nanoimprinting
Prof. Dong Sung Kim and his student Dongwhi Choi (Dept. of Mechanical Engineering) are the first to develop a one-step fabrication process to fabricate highly transparent and flexible nanotopographical triboelectric nanogenerators. Their research was published in the October edition of Advanced Materials.
The triboelectric nanogenerator, called TENG, utilizes the coupling of triboelectricity, also called contact electrification or static electricity, and electrical induction to efficiently convert mechanical energy to electrical energy. TENG is composed of a bilayer structure comprised of a contact layer and an electrode layer. After it was first report in 2012, TENG has been highlighted as an emerging system to meet a common need for an effective and sustainable energy source that benefits from its small size, high electrical output performance, and easy operation.
Researchers have been interested about the enhancement of TENG’s electrical output performance. Many researchers have reported that the nanotopographical contact layer significantly enhances the electrical output performance of TENG. Thus, the fabrication of the nanotopographical layer is important for the high electrical output performance of TENG. However, almost all previous works regarding the fabrication of TENG were based mostly on sequential multiple steps, which hinders mass production of TENG.
In Prof. Kim’s article, the one step fabrication of a transparent and flexible nanotopographical triboelectric nanogenerator is suggested by the means of thermal nanoimprinting, a low cost mass producible nanofabrication technology. An innovative aspect of using the thermal nanoimprint process is a one-step fabrication, with simultaneous nanoreplication and integration of the contact layer with the electrode layer, an essential prerequisite to construct TENG.
The fabricated TENG has high transmittance (light transmittance of approximately 88%) and flexibility (a minimum bending radius of approximately 3 mm). The nanoscale surface-relief features on TENG significantly enhances electrical output performance around 10 times higher than that of TENG with a flat contact layer. With the help of these functional characteristics, the fabricated TENG could be utilized with various applications such as wearable biomechanical energy harvesters and hybrid energy harvesters which enable the harvesting of both solar energy and aquatic energy from falling raindrops. It is expected that the one-step fabrication process of TENG in Prof. Kim’s study will play a key role in accelerating its technological development toward commercialization.
This research was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) and Pohang Iron and Steel Company (POSCO).