Transparency and bendability are some of the most attractive unique selling points for organic light-emitting diode (OLED) lighting, enabling a variety of new application possibilities for industrial and private end-users. The roll-to-roll (R2R) OLED fabrication based on thermal evaporation offers a fast, continuous-running solution for producing flexible OLEDs at a lower cost. In this work, R2R fabricated large-area highly transparent thermal co-evaporated Ca:Ag (2:1 vol.%) top-electrode with mean transmittance of 64% over the visible range and a corresponding sheet resistance of as low as 21 Ω sq−1 was achieved. By increasing the film thickness to 24 nm, the sheet resistance can be further reduced to 12 Ω sq−1, albeit with a lower mean transmittance of 58%. The Ca:Ag electrode demonstrates a high mechanical durability through 1000 bending cycles, which is highly desirable as a characteristic for flexible electronics, as well as for the R2R fabrication. Finally, the stability of the Ca:Ag electrode in vacuum and ambient was studied as well.

Large area lighting OLEDs manufactured in a Roll-to-Roll (R2R) fashion enable the well-longed production capability with considerably high throughput based on flexible substrates, hence largely reduced OLED manufacturing cost. This paper will outline the present status of R2R OLED fabrication on ultra-thin glass with the focus on transparent OLED devices and how to perform segmentation by printing of silver- and dielectric pastes. Ultra-thin glass (UTG) is laminated on a PET film to avoid fabrication interruptions when glass cracks occur during the Roll-to-Roll process. The R2R fabricated flexible OLEDs also show key-values comparable to conventional OLEDs fabricated on small rigid glass in lab-scale.

OLED lighting technology offers huge possibilities for novel lighting products. Large volume commercial success can only be achieved if unique design possibilities are consequently employed in novel application scenarios and cost effective rollto-roll production technology. The unique design options of OLED technology as well as the current status of roll-to-roll technology are therefore described in detail. Special focus is given on patterning methods.

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