Fraunhofer FEP and Sefar AG develop roll-to-roll processed large area flexible OLED
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP in Dresden, Germany, as one of the leading partners for research and development for surface technologies and organic electronics and Swiss-based Sefar AG, a leading manufacturer of precision fabrics from monofilaments, developed a roll-to-roll processed large area flexible OLED during a joint project.
Large area OLED lighting is an attractive technology for various applications in residential, architectural and automotive lighting segments. Sefar developed highly conductive, transparent and flexible electrode substrates enabling large area homogenous lighting which is demonstrated by Fraunhofer FEP in a roll-to-roll (R2R) process. OLED for lighting applications enables new form designs (large area, flexible, lightweight and thin), is one of the closest light sources to natural light, and has a low energy consumption.
"The new electrode substrate SEFAR TCS Planar is manufactured in a roll-to-roll process", explains Roland Steim, project manager at Sefar, "It is a foil-like substrate with a very high conductivity of up to 0.01 Ohm/Square and a transparency above 87%. This outstanding high conductivity originates from embedded metallic wires with a diameter of currently 40µm."
These metal wires reduce resistive losses in the transparent electrode substrate, which allows the design of larger and more homogeneous lighting solutions compared to conventional substrates like pure ITO. In addition, the embedded metallic wires are robust against bending of the substrate and less brittle than thick ITO layers on films. One challenge in the development of SEFAR TCS Planar was getting the surface as smooth as possible while parts of the metallic wires still emerge on the surface forming the electrical contact to the OLED.
Fraunhofer FEP has long-term experience in roll-to-roll processing of OLED and offers research and development services from concept studies to sample production in the field of R2R fabrication of organic-based devices on flexible substrates for industrial partners.
Stefan Mogck, head of department roll-to-roll organic technology at Fraunhofer FEP summarises: "We processed the OLED in vacuum in a roll-to-roll process on SEFAR TCS Planar substrates with a specific developed drying process and barrier film lamination. Altogether we deposited the OLED 30m in length and 30cm in width and OLED size up to 250cm²."
Caption: Large area OLED lighting (photo: Fraunhofer FEP)