The sounding rocket SubOrbital Express-4 which was launched from the Esrange Space Center outside Kiruna contained an experiment module from Karlstad University. The module is about studying how the active layer of organic solar cells forms in microgravity.

– In this project, we were able to conduct experiments in an unmanned rocket, says Jan van Stam, professor of physical chemistry at Karlstad University. It allowed us access to microgravity for several minutes instead of about half a minute, as in previous experiments in aeroplanes. We were able to perform more advanced experiments, which will hopefully give us clearer answers to questions about the structural formation, says Jan van Stam.

When the sounding rocket Suborbital Express 4 was launched from Esrange Space Center outside Kiruna, it was loaded with six scientific experiments from different countries. The rocket “Swedish” reached an altitude of 256 kilometers and provided the experiments on board with six minutes of weightlessness. In addition to the module from Karlstad University, the rocket also included five scientific experiments spanning multiple disciplines, from medicine and green energy to the birth of the universe.

To be able to conduct the rocket experiments, a new experiment module was developed in collaboration with the Swedish Space Corporation. In the module, experiments are conducted where researchers study the transition from solution to the solid, thin film that constitutes the active layer of the solar cell. When gravity is removed, phase separation – when the dissolved substances separate from each other – occurs more slowly, making it possible to study how the structure of the material changes. Being able to understand and control this process makes it possible to optimise the function of polymer solar cells. These studies can provide information about the properties of the active layer in solar cells to achieve the highest possible energy efficiency.
The experiment module is a sealed container, a 90-centimetre-high cylinder with a diameter of approximately 40 centimetres. This contains two experiment units, each with eight sample chambers. A small glass slide is coated with a solution, and then the drying process and the thin polymer film that forms when the solvent has evaporated are studied.

– We had to wait quite a while for the right weather conditions, but when the rocket was finally launched, it was the first time out of 601 launches that it succeeded on the first attempt, says Jan van Stam. It landed within the designated landing area, which is a forest area consisting of four per cent lake. You don’t want it to land in water where the rocket could be lost. It did, however, land on a lake, but the ice was strong enough. It made a hole in the ice but fortunately remained on top.

– Now the results will be analysed, and it is likely that we will apply to ESA, the European Space Agency, again to be able to conduct further experiments. The research team on site at Esrange in Kiruna included Ishita Jalan, postdoctoral fellow in physical chemistry, Leif Ericsson, research engineer in physics, and myself, says Jan van Stam.
The research is funded with the support of the Swedish National Space Agency, which is a central administrative authority under the Ministry of Education and Research, responsible for state-funded national and international space activities in Sweden. The Swedish National Space Agency also acts as the Swedish point of contact for international space cooperation.