3SUN: we improve our technology even further, with a new 27.1% efficiency record

Nine square centimetres and 27.1% of power conversion efficiency. These record figures don't lie. Our solar cell with silicon/perovskite Tandem technology reached a fundamental milestone in the transition journey toward sustainable power generation through renewable sources. The new value, reached at the lab by our specialists, in synergy with the researchers of the CEA team, of the French Institut National pour l’Énergie Solaire (INES, National solar power institute), significantly exceeds the results obtained in March 2023 - a whooping 26.5% - from a 9 cm² device. In April 2022, for the same cell, our work with the CEA team had already achieved an important outcome - 24.9% - which had then been improved in December 2022 - 25.8% - providing that the technological progress is proceeding at an impressive pace, and that we are only at the beginning of an era of great possibilities.

Behind the figures

In practice, a Tandem type cell essentially consists of two cells stacked on top of each other. One is the classic HJT, which is the silicon heterojunction model that we have already been producing industrially since 2018. The other is, however, made of perovskite. The former succeeds in utilizing radiation in the red wavelength of sunlight, the latter makes the best use of that in the blue. Their combined use in the Tandem cell improves the efficiency of individual cells and overcomes their limitations, especially for those made of silicon whose theoretical efficiency limit, that is, the limit to the amount of solar energy that can be converted into electricity, is around 29%, a value that in practice will not exceed 27-28 percent due to a number of technical factors. When silicon and perovskite solar cells are made to work together, as shown by the new record at 27.1%, completely new scenarios open up and it is possible to clearly predict efficiency values that can reach as high as 30% (a goal we aim to achieve by 2026) and beyond.

The new age of photovoltaic systems

With perovskite, then, we enter a new era of photovoltaics. The name of this class of materials features a peculiar crystallographic structure that resembles that of titanium dioxide and calcium. This structure is named after the Russian mineralogist L. A. Perovski, who first studied its properties.

In contrast, the chemical composition of photovoltaic perovskite is based on particular halides, and its ability to absorb large amounts of light immediately made this material a promising new entry in the solar industry. Indeed, the electrical charges generated as a result of perovskite's absorption of light are easily extractable in the form of electricity. In addition, the ability to change the chemical composition of perovskite allows Tandem coupling with silicon technology to be optimized in terms of solar spectrum sharing. With Tandem technology, therefore, we gain the benefits of two worlds and move toward a clear decrease in the cost of photovoltaic power generation.

The future is right here

With this goal clear in mind, we can look at the future. Also thanks to the TANGO project (iTaliAN pv Giga factOry) and the European funding for innovation on large-scale projects, we will produce solar panel for a total of 3 GW per year, and will become the largest European Gigafactory producing high-performing photovoltaic cells and modules. A goal that, translated into benefits, means greater electricity production from solar sources, a clean and renewable resource, with a long-period impact on the environment, and an important contribution toward decarbonisation. Plus the financial aspect: photovoltaic plants exploiting the Tandem technology will provide savings in the bill, and the option of generating power independently, with significant cuts in the expenditure.