Scientists have broken the efficiency record for tandem silicon-perovskite solar cells, surpassing the milestone of 30 percent for the first time. The new record takes the technology beyond the upper limits of silicon alone, using low-cost and scalable materials.
Silicon has long dominated the solar cell industry, thanks to a solid combination of efficiency, durability, cost and ease of manufacture. Decades of technological advancements have continuously increased the efficiency of these solar cells, but with current devices approaching the material’s theoretical limit of 29.4 percent, there’s not much room left for growth.
Perovskite is quickly emerging as an alternative, but it doesn’t mean that silicon is being replaced. Instead, the two materials work very well together, absorbing different wavelengths of light – silicon excels at red and infrared light, while perovskite focuses best on the green and blue parts of the spectrum.
This means that tandem silicon-perovskite solar cells have the potential to reach efficiencies higher than either can achieve alone. In 2018 the record efficiency was 25.2 percent, which was then broken twice in 2020 at 27.7 percent, then 29.15 percent. Another advance in 2021 pushed it even closer to 30 percent.
And now that milestone has been crossed for the first time. Researchers at EPFL and CSEM have developed tandem silicon-perovskite solar cells with high efficiencies using two different designs.
The first consists of perovskite layers deposited from a liquid solution onto a smooth silicon surface, which reached an efficiency of 30.93 percent for a test cell measuring 1 cm2 (0.2 in2). The second used a hybrid vapor and liquid solution technique to deposit perovskite onto a textured silicon surface, which was able to reach an efficiency of 31.25 percent for a 1 cm2 solar cell.
The researchers say that further work will be needed to investigate how well the designs can be scaled up to larger surface areas, and check their longevity.
“Tandem perovskite-on-silicon technologies have been said to have the potential to exceed the 30-percent efficiency benchmark, but this is the first time this long-predicted potential has been demonstrated, which should hopefully pave the way for even cheaper sustainable electricity in the future,” said Christian Wolff, lead researcher on the EPFL team.
Source: CSEM
