Jukka Hast

Micro Roll-to-Roll Patterning Process and Its Application on Flexible Display

Novel electrode patterning techniques on thin polymer substrates were developed on a roll-to-roll (reel-to-reel, R2R) printing system. Hot embossing, laser ablation, and lift-off processes were evaluated for mass production for active-matrix display arrays with 1000 µm display pixels by using the concept of micro electro mechanical system (MEMS) Fabry–Perot etalon. Among which, the newly developed lift-off flexography process provided the best pattern integrity with 100 µm resolution. The demonstrator of display array proved R2R printing systems possibility and capability under 1 m/s speed. A complete multilayer stack demonstration with alignment process also indicated its variable application. Further actuation for the MEMS display proved the robustness of device made by printing techniques.

Freeform and flexible electronics manufacturing using R2R printing and hybrid integration techniques

Printed electronics and other large-area roll-roll - compatible processes are opening up the new opportunity for cost-efficient mass manufacturing of electronics among other functionalities, on large-area and flexible substrates such as plastic, paper, metal foils, glass and fabrics. Data processing power and other functionalities still require high performance microelectronics circuits and therefore, also traditional electronic/semiconductor technology are also needed. These needs lead to technical manufacturing requirements that can be fulfilled best with concept of utilization combination of printed electronics and hybrid integration of silicon electronics to flexible printed platforms. Extending the continuous roll-to-roll manufacturing approach as far as possible (in air or/and in vacuum) in the manufacturing process to assembly and bonding, the manual assembly and handling phases can be almost fully eliminated. In this paper recent development to manufacture freeform and flexible electronics components and systems using printing and hybrid integration processes is presented. Production examples of hybrid integration will be presented for 1) LED display, 2) a large area roll-to-roll processed LED luminaire, 3) over-moulded optical touch panel and 4) over-moulded OLED subassembly.

Low operation voltage non self-emissive MEMS color filter pixels

A 50% reduction of operation voltage improvement was achieved on a non self-emissive color filter pixels based on MEMS (micro electro mechanical system) Fabry-Perot interference device by minimizing its Newtons rings size. Newly designed air grooves in spacer layer were proved to be efficient to evacuate air trapped inside pixels which in turn effectively lowered its operation voltage. A seesaw effect was also found if air groove occupied too large area which degrades the operation voltage lowering benefit.

Effect of the Electron Transport Layer on the Interfacial Energy Barriers and Lifetime of R2R Printed Organic Solar Cell Modules

Understanding the phenomena at interfaces is crucial for producing efficient and stable flexible organic solar cell modules. Minimized energy barriers enable efficient charge transfer, and good adhesion allows mechanical and environmental stability and thus increased lifetime. We utilize here the inverted organic solar module stack and standard photoactive materials (a blend of poly(3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester) to study the interfaces in a pilot scale large-area roll-to-roll (R2R) process. The results show that the adhesion and work function of the zinc oxide nanoparticle based electron transport layer can be controlled in the R2R process, which allows optimization of performance and lifetime. Plasma treatment of zinc oxide (ZnO) nanoparticles and encapsulation-induced oxygen trapping will increase the absolute value of the ZnO work function, resulting in energy barriers and an S-shaped IV curve. However, light soaking will decrease the zinc oxide work function close to the original value and the S-shape can be recovered, leading to power conversion efficiencies above 3%. We present also an electrical simulation, which supports the results. Finally, we study the effect of plasma treatment in more detail and show that we can effectively remove the organic ligands around the ZnO nanoparticles from the printed layer in a R2R process, resulting in increased adhesion. This postprinting plasma treatment increases the lifetime of the R2R printed modules significantly with modules retaining 80% of their efficiency for ∼3000 h in accelerated conditions. Without plasma treatment, this efficiency level is reached in less than 1000 h.