© Thor Balkhed

Organic solar cells are slowly making their way into an industry so far dominated by silicon. However, the scientific community is making a lot of efforts to support more sustainable and economical alternatives. This is the line of a project promoted from Sweden by Linköping University, which has developed a method that simplifies the production of printed organic solar cells.

In the opinion of the research team, the advantages of this type of solution justify their effort. Among them, the low cost of materials and the simplicity of the manufacturing methods are two of the most remarkable. However, this simplicity was not yet achieved when it came to creating thin and flexible solar cells of this type.

These innovations – including that of this university– use electrons with two variants of the PEDOT polymer: PPS. So while one acts as the anode, the other is modified to do so as the cathode. Between the two electrodes is the active layer which is responsible for capturing light and producing electrons. The stumbling block that this architecture ran into started when the electrodes and the active layer were printed on top of each other. In this way, any fault in one of the layers affected the other to further exacerbate, even causing short circuits.

If, to overcome this problem in the production phase, the usual response to date was to activate a current through the cell, Swedish researchers have now reversed this mechanism. To do this, the method they propose goes through use an active polymer as a glue. With this material, two layers of plastic in the system would be coated, one with the anode and one with the cathode, to then laminate the unit.

This approach made it possible to obtain the expected benefits. With only two coats included in the printing systems, the amount of defects decreases dramatically. In addition, the probability that two defects coincide on both sides and at the same point is practically excluded. At least, this is what this team ensures that in addition, to avoid problems linked to humidity, they have chosen to stratify it, as soon as possible, in protected atmospheric conditions.

© Tekniska verken

Although this type of cells they still cannot compete in terms of efficiency with silicon, the truth is that this method is advancing to enter the market. For this, this solution imagined under the direction of Olle Inganäs jumped into the business world, in particular the spin off Epishine. In it, progress is made in applying this solution to inner cells. Specifically, the company has in mind that these printed organic solar cells provide energy to power sensors such as those that measure the temperature in the home.

As the commercial launch phase progresses, the promoter of this new system sees many potentialities in it, without needing to compete with silicon cells. “Organic solar cells can be used in a multitude of contexts”, explains Inganäs, professor of organic and biomolecular electronics who cites, as the most remarkable properties of these systems, their semi-transparency, their flexibility and their low manufacturing cost.