Laser technology for thin-film transistors for wearable displays
OFweek Wearables Network News A research team led by professors KeonJaeLee and Sang-HeeKoPark from the Department of Materials Science and Engineering at the Korea Institute of Science and Technology (KAIST) has used an inorganic laser lift-off method to develop an ultra-thin transparent active-matrix backplane for flexible displays. Oxide Thin Film Transistor (TFT).
With the advent of the Internet of Things (IoT) era, strong demand for wearable transparent displays has been growing, which can be applied to various fields such as augmented reality (AR) and skin-like flexible thin devices. However, previous flexible transparent displays have some real challenges to overcome, poor transparency and poor electrical performance being two of them. In order to improve transparency and performance, past research efforts have attempted to use inorganic-based electronics, but the fundamental thermal instability of plastic substrates limits the high-temperature processes that are required for the fabrication of high-performance Electronic devices. An important step required.
This image shows an ultrathin, flexible and transparent oxide thin-film transistor produced using an inorganic laser lift-off process.
To address this issue, a research team led by Professors KeonJaeLee and Sang-HeeKoPark from the Department of Materials Science and Engineering at the Korea Institute of Science and Technology (KAIST) has used an inorganic laser lift-off method to develop ultrathin transparent oxides for active-matrix backplanes for flexible displays. Thin-film transistors (TFTs). Prof. Lee’s research group previously demonstrated inorganic laser lift-off (ILLO) techniques on energy harvesting devices (Advanced Materials, 12 February 2014) and flexible memory devices (Advanced Materials, 8 September 2014).
The research team fabricated a high-performance oxide TFT array on a laser-active sacrificial substrate. After laser irradiation from the backside of the substrate, only the oxide TFT array was detached from the sacrificial substrate due to the interaction between the laser and the laser-active layer, and was subsequently transferred to ultrathin (4 μm thick) plastic. Finally, this transferred ultrathin oxide driver circuit for flexible displays was closely attached to the surface of human skin to demonstrate the possibility for wearable applications. This adhered oxide TFT shows high optical transparency of 83% and electron mobility of 40 cm^2/(V*s) even after several cycles of severe bending tests.
Professor Lee said, “By removing the expensive polyimide substrate using our inorganic laser lift-off process, the technical barriers to high-performance transparent and flexible displays are overcome at a lower cost. In addition, this high-quality oxide Semiconductors can be easily transferred to skin-like or any flexible substrate for wearable applications.”
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