For decades, silicon has represented the heart of the photovoltaic industry, allowing the production of increasingly high-performance solar cells. However, its theoretical efficiency limit, set at 29.4%, is fast approaching, and surpassing it requires new ideas and materials. This is where the tandem solar cellsdesigned to capture more energy by combining layers with different materials. Among the main challenges, however, is that of finding materials that can complement silicon while maintaining efficiency and stability.
Halogenated perovskites: between extraordinary potential and limits
In recent years, halogenated perovskites have been at the heart of a real revolution in the solar sector. From 2009 to 2021, their efficiency increased by 579%, an impressive result compared to the modest 57% achieved by silicon in the same time frame.
The strength of halogenated perovskites lies in their ability to tolerate structural defects thanks to unique properties:
Yet these marvels of science are not without their problems: they contain lead, are toxic and easily degrade when exposed to heat, light and humidity. These weaknesses compromise their large-scale commercial application.
BaZrS3: the sustainable future of solar
Among the new solutions emerges the BaZrS3 (BZS)a chalogenic perovskite that could address the limitations of its halogenated cousins. Non-toxic, stable and with excellent optical properties, BZS stands out as an ideal candidate for next-generation solar cells.
Researchers at the Australian Center for Advanced Photovoltaics (ACAP), using cutting-edge supercomputers, have discovered how to improve the properties of BZS by applying structural strains. This treatment allows it to emulate some of the extraordinary characteristics of halogenated perovskites, while maintaining stability and environmental safety.
In a study published in Communications Materialsthe team proposes an ambitious project: stacking up to 100 ultra-thin, semi-transparent layers of BZS to increase energy efficiency. Combined with silicon, this system could go beyond 38% efficiency, a level never reached before.
Despite its potential, BZS poses production challenges. Being an extremely stable material, it requires highly controlled environments to avoid contamination, as barium and zirconium tend to bind with oxygen, compromising the quality of the final product. Despite these difficulties, BZS represents real promise for the photovoltaic sector. It could not only improve the efficiency of solar cells, but also ensure safer and more sustainable solutions for a greener energy future.
