In-line tool improves OLED manufacture

24 Feb 2006

Researchers using an in-line vertical OLED manufacturing process aim to set milestones in terms of cost-effectiveness and efficiency.

A cheaper technique for mass-producing OLED displays and lighting tiles might be a step closer thanks to research being carried out at Fraunhofer IPMS in Germany.

Vertical in-line fabrication

"The OLEDs were prepared using a new vertical in-line tool for OLED manufacture," Jörg Amelung, IPMS' Division Director for Organic Materials and Systems, told Optics.org. "Based on this vertical transportation principle and the use of organic line sources it is possible to improve throughput, masking and organic material usage."

The unique vertical in-line tool operates with continuous vertical substrate flow and linear sources for depositing organic and metallic materials. The production line at IPMS is designed for a substrate height of 400 mm and width of 470 mm or larger.

IPMS Production line

According to its makers, vertical transportation has the advantages of flexibility in substrate types and less bending of substrates and masks. They also claim that their in-line sources, where material is deposited from a linear tube (as opposed to the point sources that are more commonly used in OLED manufacture), improve material usage by a factor of 10.

Fraunhofer IPMS developed the vertical in-line technology alongside Applied Films, a firm who had already applied vertical in-line technology for LCD applications.

In addition, IPMS licensed material doping know-how from Novaled, a spin-off firm of IPMS and the technical University of Dresden, specialising in doping technology for visual displays. "We are also using the most efficient OLED technology, provided by Novaled, on the market. We have already demonstrated reduced power consumption by a factor of 3 in relation to an active-matrix LCD," added Amelung.

RGB OLEDs

According to Amelung, the dopant technology has two main advantages. "Firstly, the organic layer conductivity is high which reduces the voltage drop inside the transport layer," he said. "Secondly, the dopant technology generates real ohmic contacts with the electrode materials. Both effects increase the OLED efficiency, simplify the fabrication technology and enable the integration of OLEDs in many different substrate materials."

Author
Darius Nikbin is Science/Technology Reporter on Optics.org and Opto & Laser Europe magazine.