The researcher Mónica Lira-Cantú investigates how to improve the technology of voltaic cells

One of the great challenges in dealing with climate change is to replace the consumption of fossil fuels with clean energy sources. Mónica Lira-Cantú, from the Catalan Institute of Nanoscience and Nanotechnology (ICN2), is working on the design of a new generation of solar cells made of perovskite, a mineral with a crystalline structure called to revolutionize photovoltaic energy. Her group has achieved that, in addition to being efficient, these solar panels are also more stable and do not lose performance after a thousand hours of continuous lighting in the laboratory.

How does the new generation of solar cells in which they work?

We manufacture nanomaterials that we put in a solution and then print solar cells in different ways. We no longer need complex manufacturing techniques that use a lot of energy, but rather we make them in the laboratory at room temperature and conditions. For example, we can print the cells one by one or continuously. If you print on fabric you can make clothes, or if you print it on other items, for example, a hat, you take it fishing or to the beach and connect your mobile or the electronic device you want to recharge it directly. Being light and flexible, imagine the possibilities! Imagine being able to paint the walls of your house and that wall already gives you energy directly.

“Perovskite solar cells have revolutionized photovoltaic technology”

Will these solar panels not have to be placed on the roof of a building?

The current silicon ones need the sun to reach them directly at an angle of 90 degrees. In contrast, our cells do not need direct light to obtain energy. Imagine the importance for buildings. You no longer have to have the solar panels on the roof and calculate the great weight that all that infrastructure means for the building. We can have solar panels printed on windows or walls, for example.

What is the efficiency and stability of these plates?

At the laboratory level, perovskite solar cells already have the same efficiency as silicon ones, around 26%. The big problem for this technology to be commercialized is that we do not have the same stability. We investigate so that these cells work for years without degrading. The importance of the work that we have published is that we can separate the properties that imply having good efficiency from those that imply having good stability.

Why were the results of your article unexpected?

We did not expect to be able to separate the efficiency and the stability of the material, we had always thought that they were united. This was a big problem, because to improve efficiency we had to improve stability. Now it is no longer necessary and we can improve its stability without having to worry about efficiency.

Until now, if you wanted to improve the efficiency of the perovskite cell, did you also have to do it by affecting its efficiency?

Exactly. It was thought that if you made a high-efficiency perovskite solar cell it was automatically very stable, because you are supposed to have made it in such a way that the layers have very good structural quality. It was assumed that if they were very efficient, they were also very stable.

Are perovskite cells already on the market?

Not yet, because they are still not stable enough to be marketed. If with this research we manage to show that this technology has been around for years and can be useful for some application, it will be commercialized in a very short time.

The cost is also important; Is it cheaper to print continuously?

To produce a single crystal of silicon, the material needs to be melted at a temperature of 1,200ºC. On the other hand, with perovskite, since it has an ink like that of pens, you can print wherever you want and at room temperature. The cost is very different, although right now the price is not an advantage either, since silicon is very cheap due to subsidies from the Chinese government.

Is this technology relatively new?

Compared to other technologies, perovskite solar cells have developed very quickly. In the last ten years its efficiency has risen from 3% to 25.8% where we are now. This has been a boom that has revolutionized all the photovoltaic technology that exists right now.

What does the initiative behind Women in Renewable Energy consist of?

In 2019 we promoted these annual conferences with the researcher Zakya Kafafi in which women scientists with a recognized career participate. Above all we do it to encourage young researchers and not give up. It is important to have role models, especially in areas such as physics and engineering, where there are few women.