In Switzerland, traditional roof tiles are increasingly being replaced by large, black and blue panels that convert sunlight into electricity.
These panels, made predominantly from silicon, are the norm for solar cells today.
However, despite years of advancements, the efficiency of silicon-based solar cells is reaching its maximum potential, capped at about 33% due to inherent material limits.
Researchers at Empa, led by Fan Fu in the Laboratory for Thin Films and Photovoltaics, are exploring alternatives that promise even greater efficiencies.
One such promising material is perovskite, known for its adaptability and efficiency in solar technology.
Perovskite stands out because its properties can be easily adjusted to enhance solar cell performance.
By using two layers of perovskite with different properties, researchers can create “tandem solar cells” that capture more energy from sunlight.
One layer absorbs high-energy photons while the other captures lower-energy ones, potentially achieving efficiencies up to 45%.
Currently, the Empa team is focusing on developing all-perovskite tandem cells as part of the European research project SuPerTandem, collaborating with 15 other leading institutions and companies.
Their goal is to create flexible, efficient solar modules using scalable and cost-effective production methods.
Unlike silicon cells, which require high-purity crystals and high-temperature processes, perovskite cells can be produced through methods like printing, solution processing, or vapor deposition.
These methods are not only more environmentally friendly but also produce less impact from small defects on the cells’ performance.
The benefits of high-efficiency perovskite cells are significant. They could reduce the cost of solar power, as the cells themselves are a small part of the overall cost of a photovoltaic (PV) system—the bulk of the cost comes from installation and components like cables and inverters.
More efficient cells mean smaller, more affordable systems for the same power output.
Perovskite cells can also be made on flexible substrates instead of rigid glass, expanding their potential applications to places like car roofs or buildings that cannot support heavy loads.
The journey from the lab to the rooftop involves scaling up the size of the perovskite cells from small prototypes to industry-standard panels and ensuring they are durable enough to withstand weather conditions.
Despite these challenges, Fan Fu is optimistic. With rapid progress and strong industry interest, he believes that perovskite solar cells could be a common sight within the next five to ten years.
This timeline is particularly impressive considering that perovskite solar cells have been under study for just about 15 years, compared to nearly 70 years of research on silicon cells.
