Skip to main content

Advanced laser ablation barrier films for organic and large area electronic devices

Periodic Reporting for period 3 - ALABO (Advanced laser ablation barrier films for organic and large area electronic devices)

Reporting period: 2017-01-01 to 2017-12-31

The overall approach of the project is developing organic electronic building elements on flexible substrates with monolithically integrated barrier foils as substrate. The barrier acts as inevitable protection against atmospheric gases as water vapor and oxygen as the most crucial agents for unwanted material degradation processes. This topic is one of the keys for enhancing both performance of TOLAE components and addresses some of the main technology barriers of TOLAE: lifetime and cost-performance ratio.

Current state of the art in flexible OPV is the encapsulation in between additional ultra-barrier foils to achieve relevant lifetimes. So far, these layers are delivered as coatings on dedicated polymer foils, such as PET. There is a small number of suppliers and low production volumes. As a result, the ultra-barriers are among the main cost drivers of OPV technology. By using two different kinds of foils, one for the substrate and the transparent electrode and the other one coated with an ultra-barrier film, there is no interference between laser structuring on the barrier, since the barrier foil is attached after all OPV deposition and scribing steps.
Motivation of the ALABO project was the simplification of devices by reducing the number of production steps and needed materials. The ultimate goal was the replacement of the four polymer layer system of OPV devices by just two or in wider future even only by one polymer foil. This objective was approached by integration of a barrier layer instead of using a separate encapsulation foil.

As reference system for such highly integrated devices organic photovoltaic modules (OPV) have been chosen. They are high-level state-of-the-art stacked and layered electronic devices. Thus, they served as a well-suited demonstration object for a scalable and general approach suitable also for other TOLAE devices. Without technological and economical alternative, laser ablation processes in various dedicated forms had to be developed to realize the interconnection of small solar cells to a full device in line. The ALABO consortium performed intense R&D work in four crucial fields of interest: material development for an high-performance, yet laser-suitable solar device stack, development of three different laser processing technologies with focus on barrier and opto-electrical characteristics maintenance even-handed, development and qualification of close-to-process characterization methods and the development of an industrially-suitable roll-to-roll machine concept for the continuous manufacturing of OPV with 1.2m web width.
All of these R&D fields have been addressed positively by the ALABO partners, the achieved results in their respective field of work significantly enhanced their competences, the latter being proofed by various publications.
The success of the project was demonstrated by the fabrication of OPV demo devices with state-of-the-art opto-electrical performance based on barrier-integrated design and thus, avoidance of front-side encapsulation foil.
So-called “integrated frontsheets” have been developed and used in large area organic electronic devices for the 1st time. As barrier system a development from Holst Centre Eindhoven is used in the project which is covered by a transparent DMD (dielectric-metall-dielectric) front contact. Structured laser machining of the DMD front contact layer, the organic active layer and the back electrode layer have been central issue of ALABO’s R&D work. Beyond state-of-the-art, all three laser processes have been positively developed without damaging the integrated barrier layer. As a result, suggestions for industrially suitable laser setups and processing strategies have been given.
As close-to-process monitoring tools regarding the laser processes, the barrier performance and the final device efficiancy, various methods have been tested, cross-checked and calibrated. It was possible to bring the laboratory standard method’s precision closer to the process.
An important issue was the demonstration of the up-scale-ability of the developed P1, P2 and P3 processes in a R2R machine with an addressed web width of up to 1200 mm. Further research was performed to improve the recognition of scribes and the accuracy of scribe positioning under difficult lighting conditions. A sophisticated solution was found and patented.
ALABO contributed significantly to a realistic vision of ressource-efficient and local energy harvesting technology, less dependence on fossile sources and competitive European manufacturing.