posted on 2023-03-11, 14:03authored byJunhong Park, Chan Young Kim, Myeong Ji Kim, Seungyeop Choi, Yong Ha Hwang, Kyung Cheol Choi
To implement wearable textile displays (WTDs), it is
essential
that unique properties such as physical and chemical properties, aesthetics,
and flexibility of the textile be maintained. Therefore, thin film
transistors (TFTs) for WTDs should exhibit excellent electrical properties
to enable 4K and 8K high resolution and high frame-rate (>120 Hz)
displays while maintaining the properties of textiles. All layers
of TFTs were formed by vacuum deposition and oxide-based transparent
materials; amorphous In–Ga–Zn-O (a-IGZO), indium tin
oxide (ITO), and Al2O3 were used. A transparent
and flexible electrode with an ITO/Ag/ITO (IAI) structure was optimized
and applied to the source/drain and gate. All processes were performed
below 150 °C, and the wet-step was eliminated to prevent physical
and chemical deformation of the substrate. The flexible, transparent,
high mobility a-IGZO TFTs (FTH TFTs) for WTDs were fabricated on glass,
polyethylene terephthalate (PET) film, and textile substrates, respectively.
Their electrical performance, transparency, and flexibility were then
compared. The textile-based TFTs showed transmittance of 72.98%, high
mobility of 11.5 cm2/(V s), and an on/off ratio of 9.28
× 107 even in a low temperature process (<150 °C).
In addition, the electrical properties of the textile-based TFTs were
maintained despite testing entailing 1000 cycles of bending with a
tensile strain of 0.8%. In particular, the FTH TFTs for WTDs were
able to stably drive a red organic light-emitting diode on textile.