Solliance - Page 5

Solliance, a partnership of R&D organizations from the Netherlands, Belgium and Germany working on thin film photovoltaic solar energy, recently demonstrated an industrially-applicable roll-to-roll process for the production of solar cells achieving a record 12.6% conversion efficiency on cell level. This result allows for an accelerated market introduction of this attractive new source of renewable energy.

The roll-to-roll (R2R) process was developed for both the electron transport and the perovskite layers on the new Solliance dual R2R coating line. The in-line roll-to-roll coating, drying, and annealing processes were executed at a linear speed of 5m/min on a 30-cm wide commercial PET/ITO foil and under ambient conditions. All process steps on this roll-to-roll line were performed using low-cost materials while keeping the process temperatures below 120 ⁰C, which is indicative of the production potential of this new emerging thin film PV technology.

Researchers at Eindhoven University of Technology (TU/e) and research institute ECN (part of the Solliance collective) have found that adding a thin layer of aluminum oxide helps protect a perovskite solar cell against humidity, as well as add a yield boost of 3%.

The scientists covered the sensitive layer of perovskite with a few atomic layers of aluminum oxide to protect against degradation caused by humidity. These layers are contained within the solar cell, between the layers of perovskite and electric contact. The researchers chose aluminum oxide (Al2O3) since it can form immediately on any kind of surface. The team explained that despite the fact that Al2O3 has electrically insulating properties, it can still be used as a buffer layer between the semi-conductive perovskite and the conductive contacts by limiting the thickness of the layer to one nanometer or less. This way, charge carriers can then tunnel electrically through the insulator layer.

Solliance announced a 10% aperture area power conversion efficiency for its up-scaled thin-film perovskite photovoltaic modules. The efficiency was measured on an aperture area of 168 cm². Twenty-five cells were serial connected through an optimized P1, P2, P3 interconnection technology. The PV module was realized on a 6x6 inch glass substrate using industrial scale-able slot die coating in combination with laser patterning.

Based on previous optimization on 16 cm² modules, the Solliance team was able to transfer this to a 6x6 inch sized glass substrate using the developed blade coating process and the optimized mechanical patterning technology. These results demonstrate the up-scalability of this new thin film PV technology. Apart from the electrodes currently used, all layers can be processed in ambient environment and at temperatures below 120⁰C. Furthermore, the deposition and interconnection technologies used for obtaining these results are industrially available for Sheet-to-Sheet as well as for Roll-to-Roll manufacturing. The latter allows for creating high volume production in the future.

Solliance, a partnership of European R&D organizations working in thin film solar energy, recently announced that Panasonic has joined its research program concerning the development of roll-to-roll manufacturing processes aimed at large scale production of flexible perovskite solar cells as one of the industrial partners.

Research will be carried out at the Solliance pilot production facilities on the High Tech Campus in Eindhoven, the Netherlands, and in the research facilities of imec in Leuven, Belgium. Panasonic will conduct the feasibility studies on the possibility of large scale roll-to-roll production of printed PSCs under this program. This partnership will create a technically capable and commercially focused effort to roll out this next generation technology.