Ultra-thin transistors promise high-performance, transparent wearable displays

Technology News | August 11, 2016

By Rich Pell

Published in the journal of Advanced Functional Materials, their findings “Skin-Like Oxide Thin-Film Transistors for Transparent Displays” relate to the fabrication of ultrathin and transparent oxide thin-film transistors (TFT) using the inorganic-based laser lift-off (ILLO) method they had already successfully developed for energy-harvesting and flexible memory devices.

The research team fabricated a high-performance oxide TFT active-matrix backplane on top of a sacrificial laser-reactive substrate, which after laser irradiation from the backside of the substrate, separated from the sacrificial substrate. The TFT array layer was then transferred onto an ultrathin plastic film carrier (polyethylene terephthalate), only 4µm thin.

When transferred conformally to a heavily textured surface such as the human skin or artificial leather, they found the ultrathin-oxide driving circuit to have an optical transparency of 83% while maintaining a fairly high mobility of 40cm² V⁻¹ s⁻¹ even under several cycles of severe bending tests.

Ultrathin, flexible, and transparent oxide thin-film transistors attached to leather. Credit: KAIST

With their ILLO process, the researchers claim they have overcome the technological barriers for high performance transparent flexible displays at a relatively low cost, removing expensive polyimide substrates.

They also demonstrated that the TFT active-matrix backplane obtained could be easily transferred onto skin-like or any flexible substrate for wearable applications without suffering any structural damage.

This, they hope, will open the door to pervasive display applications such as pictured in the representation below.