Higher yields for roll-to-roll flexible electronics Roll-to-roll (R2R) processing could revolutionise the manufacturing of large-area organic electronics and be used to mass produce photovoltaic roofing panels and flexible flat panel displays. New technologies developed to deal with defects and contaminants promise to overcome current barriers to higher yield at lower cost. Industrial Technologies © Thinkstock Photolithography is the workhorse behind electronics. Since its invention in the 1950s, this technique has shrunk the size of printed circuit features 400-fold. However, lithography is expensive because it can only pattern small areas at a time. And today, the electronics industry prefers to use flexible substrates, lighter and more rugged than silicon ones. R2R processing enables rapid and low-cost manufacture of flexible substrate materials, new patterning techniques and robust barrier layer packaging. One of the most pressing challenges of implementing R2R to fabricate organic electronics is the lack of suitable technologies to detect and repair defects on the nano scale. Defects and contamination diminish product quality and, ultimately, its lifetime. These problems were the focus of the EU-funded project CLEAN4YIELD (Contamination and defect control for increased yield for large scale R2R production of OPV and OLED). This three-year project brought together commercial and research partners from Europe and Israel to develop new technologies that will ensure high enough yields for cost-effective manufacturing. The project partners developed technologies for the detection of particles with size in the 100 to 300 nm range in large rolls. All have been transformed into prototypes that were evaluated in partner R2R lines. In addition, they developed tools for electrical defect detection in organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs) at standard process speeds. Several cleaning technologies have also been successfully implemented. One removes up to 99 % of particles down to 100 nm in size from various substrates. A set of elastomers and adhesives is the first cleaning solution that can be used in vacuum systems. Along the same lines, several contamination prevention technologies have been tested at partner sites, among them an intrinsically clean film. The CLEAN4YIELD project partners adopted a holistic approach to address problems that are common to OLEDs and OPVs as well as moisture barrier foils deposited on flexible substrates, which are easily applicable to other thin-film technologies. Improved detection and cleaning will enable high-quality mass production of a variety of important products. New technologies developed within the CLEAN4YIELD project will help open new market areas for Europe's instrumentation and equipment industries. Enhancing the lifetime of organic electronic products while minimising the wastage of expensive raw materials and, thereby, lessening the environmental impact will increase sustainability. Keywords Roll-to-roll, organic electronics, CLEAN4YIELD, OLED, organic photovoltaics, cleaning technologies
