Projects

Flexible OLED Displays

Flexible organic light-emitting-diode (OLED) displays are the next-generation of displays providing for the enjoyment of full-color moving images, with a display that is thin like paper, light, bendable, and mechanically durable.

Flexible OLED displays are comprised of organic thin film transistor (OTFT) and OLED devices formed on very thin plastic films. To operate the OLED display requires OTFT devices with higher performance than those required for other displays. We must ensure not only the performance of the individual transistors, but also work to control the variations among several hundred thousand individual devices, and insure reliable performance. Taking this into consideration, applied research projects are being carried out with the aim of realizing flexible displays consisting of high-performance OTFT and highly efficient OLED devices.

Printable Radio Frequency Identification (RFID) Tags

Radio frequency identification (RFID) tags enable the development of large markets for security, logistics, and medical care. Compared to bar codes, RFID tags have many advantages because they are rewritable and have multi-readability. However, devices require the relatively high manufacturing cost vs. conventional RFID tags is imperative to producing more inexpensive products and broadening the use of RFID.

Printing processes are expected to reduce the manufacturing costs for RFID tags. Accordingly, we have focused on fabrication of fully printed RFID tags that include both antennas and the required circuitry. In order to realize printed RFID tags, high-resolution patterning and organic integrated circuits with high frequency response are important, which we are working to improve.

Reliability of Printed Organic TFT Devices

Organic TFTs are sensitive to external influences such as air ambient, high temperatures and DC voltages. To evaluate reliability of organic TFT devices we should consider both chemical and physical influences because multiple variables that can affect the organic TFTs and semiconducting materials, such as: molecular changes through oxidization; changes of crystal structures through elevated temperatures; the interface between semiconductor and electrode layers; and the surface topology of the dielectric layers.

In particular, when organic TFT devices are fabricated with printing technologies, organic solvents and other factors will degrade the electrical performance and the interface characteristics between organic semiconductor layer and electrode or dielectric layers. Printed organic TFTs are tend to be worse than those of TFTs fabricated by vacuum-based evaporation. We attempt to standardize the methods and technologies for evaluating and improving the reliability for printed organic TFT devices, in order to help realize their full commercial potential.

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