Perovskite cells advance in one of their great challenges to become the future of solar energy: improve their resistance and duration

For some years now, photovoltaic technologies have looked to perovskites as the “holy grail” of the sector, the great hope for the promotion of solar energy. A year ago Ignacio Mártil de la Plaza, Ph.D. in physics and professor of electronics, explained to us that the materials included under that label are endowed with “optimal” properties to transform solar energy into electricity that make them ideal candidates for panel manufacturing. Although their development in recent years has been remarkable and they have achieved in just a decade what took half a century for silicon, the reality today is, however, that perovskites present significant handicaps, such as their degradation and limited life Useful. However, 2022 starts with good news.

A group of chemists Kaunas University of Technology (KTU), in Lithuania, has achieved increase the stability and durability of perovskite solar cells, which tackles one of its great weak points: environmental degradation. And it has also done so by providing the material with a level of efficiency that the scientists themselves describe as “extremely high”.

Using a process known as passivation, which targets the active layer of the solar cell and removes defects that are generated during manufacturing, the team has achieved 23.9% efficiency with long-term operational stability (over 1,000 hours). “It is a simple but effective way to improve the stability of perovskite solar cells,” highlights the KTU itself in a statement: “The passivated surface becomes more resistant to environmental conditions, such as temperature or humidity, and more stable, extending the durability of the device”.

An economical alternative

It is not the first time that researchers have used passivation to improve perovskite solar cells, but the KTU team – which has worked side by side with a group of experts from China, Italy, Lithuania, Switzerland and Luxembourg – has wanted to avoid one of its drawbacks: the formation of a layer that ends up causing the solar cells to heat up. To achieve this, they used different synthesized phenylethylammonium iodide isomers.

The materials were commissioned to test them in “perovskite minisolar modules” by a group from the Federal Institute of Technology in Lausanne. During the test it was possible “record efficiency” solar energy conversion of 21.4%. “It proved to be quite effective in preventing the negative effects of passivation on solar cells. An isomer with the closest passivation groups to each other has been found to lead to the most efficient passivation.” explica el doctor Kasparas Rakštys.

In addition to their optimal properties, perovskite solar cells allow the manufacture of thin, light, flexible and with low cost materials, which has made them one of the fastest growing solar cell technologies globally. Compared to silicon crystals, perovskites offer important advantages: they can be produced easily and cheaply. Good proof of this interest is that the KTU study, published in the journal Nature Communications, is not the only one who has tried to perfect it in recent months.

In December Nature Energy echoed of the work of a group of researchers from the Forschungszentrum Jülich, in Germany, who presented a variant that stands out for its stability. During testing, at high illumination and around 65 degrees Celsius over 1,450 hours of operation, the perovskite cell retained 99% of its initial efficiency.

“The solar cell that we have now presented impresses with its exceptional stability. Long-term prediction is always difficult, but the solar cell we have now developed could certainly operate for more than 20,000 hours under normal circumstances”, explained Professor Crhistoph Brabec, from the Helmholtz Institute Erlangen-Nuremberg, a Science Daily.

The goal is very similar to that of their Lithuanian colleagues: tackle the short lifetime of perovskites, one of its great handicaps. In the race to perfect the technology, the University of Cambridge has also stood out in recent months, at the end of 2021 presented a method to stabilize the material without compromising its performance. In their purpose they used an organic molecule as a “template”. In the last weeks the Chinese Academy of Sciences (CAS) have also presented advances that point to the “self-repair” of the cells themselves.

Images | Lilly, Viktor, Ludvig, Kim & Gitte Andersen (Flickr) Y Ricketyus (Flickr)