Sony Corp. has developed a TFT substrate in which all the structures on the plastic substrate are made from organic materials and prototyped an LCD panel using this substrate. The components made from organic materials include the electrodes and wiring, TFT, gate insulator, encapsulation film, and buffer layer. "We are the first in the industry to announce the fabrication of these components all from organic materials. The structures provided on a flexible plastic substrate are liable to break. Thus, it is ideal to form them from organic material," said a spokesperson.

Among these structures made from organic materials, the electrodes, wiring, gate insulator and buffer layer were made by coating. Photolithography technique excluding the vacuum process was adopted to form the electrodes and wiring that require patterning. The TFT and encapsulation film were made by vapor deposition.

The organic materials used are as follows: organosilver compound for the electrodes and wiring, pentacene for the TFT, OTS-containing PVP (Polyvinylphenol) for the gate insulator, polyparaxylene for the encapsulation film, and PVP for buffer layer. This time, Sony prototyped the LCD panel by combining that TFT substrate with polymer-dispersed liquid crystals. It is a 2.5 inch panel featuring a pixel count of 160 x 120, and the pixel pitch of 320 μm. The drive voltage is +10 V.

Takuya Otani, Nikkei Electronics