MK Nazeeruddin / EPFL

Perovskite is another step towards being the photovoltaic panel material of the future. The latest breakthrough comes from a scientific group from the Ecole Polytechnique de Lausanne (EPFL) which has produced perovskite solar cells with an efficiency of 19% and, key, stable. This was possible thanks to the incorporation into cells of guanidinium, with which performance was maintained for 1000 hours of continuous light exposure.

According to the scientists who participated in this project, which among other things collaboration of the University of Córdoba and Abengoa Reserch, the result obtained in the laboratory would translate, in practice, into 1,333 days of effective use of this technology, without suffering any loss in performance.

“It is a fundamental step in the field of perovskite”says Mohammad Khaja Nazeerruddin, project member. And it is that its advance can end the classic problems of perovskite for its leap to a commercial scale, such as lack of stability. The crystalline materials that make up perovskite are subject to degradation over time. This, in addition to the uncertainty, translates into increased costs in the area of ​​marketing.

MK Nazeeruddin / EPFL

However, this research takes a step forward in this regard, by strengthening the stability of these cells and by achieving an efficiency close to 20%, which is approaching step by step 25% of conventional solar cells made of silicon.

How was this advance possible? Take a path that had already been explored: synthesize perovskite materials that could maintain their effectiveness over time. This option had already been tested with options such as rubidium or cesium. These bets, however, were “Difficult to implement and expensive”, ensures in a EPFL declaration.

As an alternative, this team opted for improving the stability of perovskite with the introduction of an organic guanidinium cation in lead methylammonium iodide. Thus, it was found that, By inserting this type of cation into the crystal structure of perovskite, it is possible to enhance the thermal and environmental stability of the material.. So much so that in what is called the Goldschmidt tolerance factor, an indicator of the stability of crystal structures, guanidinium obtains 1.03. The data is very close to “Ideal tolerance factor”, which is at 1, or slightly below. With these results, the group considers that it is opening “A New Paradigm for Perovskite Design”.