High Mobility, Low Off-Current, and Flexible Fiber-Based a-InGaZnO Thin-Film Transistors toward Wearable Textile OLED Displays

Fiber-based organic light-emitting diodes (OLEDs) are gaining attention as promising candidates to achieve truly wearable textile displays because of their favorable electrical and mechanical characteristics. However, although fiber OLEDs have been developed into passive-matrix displays, it has not been possible to achieve active OLED operation because of the difficulty of realizing fiber-based thin film transistors (TFTs) with the proper electrical and mechanical performance at the same time. Here, 1D cylindrical fiber-based IGZO TFTs, which simultaneously exhibit a high electrical performance and flexibility, are reported. To address this trade-off relationship, four key stages of a novel fabrication process and unique device structures that suitable for the thermal properties and cylindrical structure of the fiber were applied: (I) prethermal treatment, (II) partially patterned layers, (III) coplanar structure, and (IV) continuous postannealing (CPA) process. As a result, the fabricated fiber-based IGZO TFTs showed high mobility (8.6 cm2/(V s)) and low off-current (similar to 10-12 A), comparable to that glass-based TFTs, as well as flexibility. Furthermore, based on these valid performances, it was demonstrated that fiber phOLEDs could be driven by fiber-based IGZO TFTs using a wiring connection with Cu wire and Ag paste. The results suggest that this may allow the potential fabrication of fully textile AMOLED displays, integrated with TFTs.