Companies show ITO-free, Printed Flexible OLED lighting, paving the way to low-cost large-size OLEDs

Agfa, Philips and the Holst Center are showing a large-area (12x12cm2) flexible OLED - without ITO as transparent electrode, and with printed shunting lines. This means that costly materials and lithography processes are not needed, and the OLEDs are much cheaper.

Up till now, ITO was needed as supporting layer for the PEDOT/PSS* anode layer with lower conductivity. Thanks to Agfa’s high-conductive transparent polymer OrgaconTM, a PEDOT/PSS-based solution with six orders better conductivity than its predecessor, the use of ITO can now be avoided. Proof is the latest OLED lighting demonstrator of Holst Centre’s shared programs: a homogeneous white OLED tile of 12x12cm2 without the use of ITO.

To obtain homogeneous light distribution over large surfaces like this, some kind of additional current distribution is still needed. Even in the presence of ITO, a grid of metallic shunting lines is needed. In conventional designs, ITO, shunting lines, and insulation lines covering the shunting lines are patterned using photolithography steps. Holst Centre and its partners have succeeded in direct patterned deposition of these shunting lines by inkjet printing, and combining it with PEDOT/PSS without the need for any photolithography steps. To our knowledge, this is the first time that ITO-free flexible OLEDs are demonstrated in combination with printed shunting lines, which is an important step towards low-cost manufacturing. According to recent reporting, OLED lighting is expected to hit the market already in the course of 2011.

This was achieved with partial funding from the Fast2Light project.