[FPD International] Tokki, GE Co-develop Film Sealing Equipment for Organic EL Devices

Oct 23, 2007
Masao Oonishi, Nikkei Microdevices
Samples made with the film sealing equipment. The luminous layer is about 1 × 1cm. Sealing films cover the luminous layers. Transparent ITO electrodes look like crossing at right angles on the luminous layers.
Samples made with the film sealing equipment. The luminous layer is about 1 × 1cm. Sealing films cover the luminous layers. Transparent ITO electrodes look like crossing at right angles on the luminous layers.
[Click to enlarge image]
PV-CVD equipment that can deal with the fourth-generation glass substrates
PV-CVD equipment that can deal with the fourth-generation glass substrates
[Click to enlarge image]

Tokki Corp prototyped a plasma CVD (chemical vapor deposition) film sealing equipment for organic EL devices and confirmed its ability by sealing some organic EL layers. The company has been developing the equipment with GE Global Research, central laboratory of General Electric Co of the US.

By improving the productivity of the equipment, Tokki aims to release sealing equipments for mass production of organic EL devices within 2008. Compared with glass sealing, which is currently used, film sealing enables to reduce the number of parts and devices and can be applied to flexible panels, the company said.

The prototype of the equipment will be exhibited at FPD International 2007 from Oct 24, 2007, at Pacifico Yokohama, Yokohama City, Japan.

The newly-developed sealing equipment can be used for the fourth-generation glass substrates (730 × 920mm), which the company's other organic EL device manufacturing equipments can deal with. The verification of the technology was conducted with a 200 × 200mm glass substrate.

An Alq3 organic EL layer, which is about 1 × 1cm and sandwiched between transparent ITO electrodes, was formed on the glass substrate. Then, thin sealing films of several nanometers thick were accumulated on the layer.

The sealing films were developed by GE Global Research. Several organic and inorganic layers are piled up to form a barrier film that prevents a luminous layer from deteriorating by protecting it from humidity and gases.

Compositions of the organic and inorganic layers are gradually changed to form a film so that the degree of adhesion between layers increases. And the high degree of adhesion will help to prevent cracks on the film when it is used for flexible substrates in the future, the company said. Its gas barrier ability is in the level of 10-6g/m2 per day.

Film sealing does not need sealing glass, adhesive, desiccant agent and others. Also, film sealing enables to make thinner devices because it does not require glass.

Glass sealing requires about five processes such as cleaning sealing glass and vacuum degassing in addition to automated transportation systems between those processes. In film sealing, only one process, vacuum chamber, is needed.

"We want to cut the price of the equipment by half (compared with glass sealing equipments)," said Osamu Oshinden, senior manager of the corporate planning department in Tokki.

To achieve this goal, in the second stage of the joint development, settings will be adjusted to improve productivity by reducing takt time and using larger substrates, he said. The first target will be OLED panels, but flexible OLED panels and OLED lamps will be the next targets, he added.

Tokki and GE announced in January 2007 that they launched a one-year joint development project toward the practical use of film sealing technologies for organic EL devices.