Revolution in solar energy: 33.1% efficiency thanks to new passivation!

Revolution in solar energy: 33.1% efficiency thanks to new passivation!

An international research team involving the King Abdullah University of Science and Technology (KAUST), the University of Freiburg and the Fraunhofer Institute for Solar Energy Systems ISE has made remarkable progress in the efficiency of perovskite-silicon tandem solar cells. These innovative solar cells combine a perovskite top cell with a silicon bottom cell and use advanced passivation methods to achieve increases in efficiency that far exceed what was previously possible. Dr. Oussama Er-Raji, lead author and postdoctoral researcher at INATECH at the University of Freiburg, reports impressive results that were published in the journal Science.

While conventional silicon solar cells achieve a maximum of 29.4 percent efficiency, the passivated tandem solar cells were able to achieve efficiencies of up to 33.1 percent. The treated cells also had an open-circuit voltage of 2.01 volts. This is a significant advance since the passivation technology used so far was limited to flat surfaces. The new method of passivation, by depositing 1,3-diaminopropane dihydroiodide onto uneven surfaces, has proven to be crucial.

Innovative passivation for the future

Passivation not only improves the efficiency of the cells, but also increases conductivity and fill factor. What is particularly noteworthy is that passivation in perovskite solar cells affects the entire layer, in contrast to silicon solar cells where it only affects the upper layers. This discovery could serve as a basis for future research and offers promising prospects for the development of even more powerful solar cells

The results are closely related to the Fraunhofer lighthouse project “MaNiTU” and other initiatives such as “PrEsto” and “Perle”, which are funded by the Federal Ministry for Economic Affairs and Energy (BMWE). These projects focus not only on increasing the efficiency but also on the sustainability of solar cells.

Compatibility of efficiency and sustainability

In addition, researchers at the Fraunhofer company are researching materials with a perovskite crystal structure, where they found that only lead-containing perovskites are able to achieve high efficiencies. Although these materials are currently efficient, a challenge lies in finding alternative, non-toxic, lead-free materials. Despite these challenges, scientists have made significant progress in developing highly efficient demonstrators. An example is a perovskite-silicon tandem solar cell with an area of ​​over 100 square centimeters, made by screen printing metallization.

The advanced recycling processes explored in the projects could enable a circular economy for lead-containing perovskites. This research, concerned with the production of new materials and the development of appropriate manufacturing processes, is crucial to bring photovoltaic technology back to the forefront of global competitiveness.

As part of “MaNiTU”, new production processes were also developed that enable a high-quality perovskite thin film. An integrated production line addresses the temperature sensitivity of the perovskite cells, which requires production below 100 °C to ensure the quality of the front contact structures. These technological advances demonstrate the potential that has not yet been fully exploited in the field of solar energy.

In summary, the scientific work shows that the future of perovskite-silicon tandem solar cells is promising and that both efficiency and sustainability are in focus. This innovative research team is proposing an important path for the next generation of solar technologies.