Researchers develop ultra-thin transistors for wearable display

Seoul: A research team at the Korea Advanced Institute of Science and Technology (KAIST) has developed ultra-thin and transparent oxide thin-film transistors (TFT) that can be used to make high performance wearable and transparent displays.

With the advent of the "Internet of Things" era, strong demand has grown for wearable and transparent displays that can be applied to fields like augmented reality and skin-like thin flexible devices. But flexible transparent displays developed in earlier studies face challenges like poor transparency and low electrical performance. 

Led by Keon Jae Lee and Sang-Hee Ko Park from KAIST, researchers set out to overcome these challenges by using the inorganic-based laser lift-off (ILLO) method, according to the study published recently in the journal Advanced Materials. 

"By using our ILLO process, the technological barriers for high performance transparent flexible displays have been overcome at a relatively low cost by removing expensive polyimide substrates. Moreover, the high-quality oxide semiconductor can be easily transferred onto skin-like or any flexible substrate for wearable application," Lee said.

The team fabricated a high-performance oxide TFT array on top of a sacrificial laser-reactive substrate. After laser irradiation from the backside of the substrate, only the oxide TFT arrays were separated from the sacrificial substrate as a result of reaction between laser and laser-reactive layer, and then subsequently transferred onto ultrathin plastics. 

Finally, the transferred ultrathin-oxide driving circuit for the flexible display was attached conformally to the surface of human skin to demonstrate the possibility of the wearable application. The attached oxide TFTs showed high optical transparency of 83 per cent.