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New solar cell coating triples efficiency, stability and conversion rate
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New solar cell coating triples efficiency, stability and conversion rate

A new protective coating has significantly increased the energy conversion efficiency of perovskite solar cells.

Developed by scientists at Northwestern University, the coating also extends the life of perovskite solar cells. Based on amidinium, the robust layer was 10 times more resistant to breakdown than typical experimental ammonium-based coatings.

The researchers claimed that guanidinium-coated cells also triple the cell’s T90 lifespan, the time it takes for a perovskite solar cell’s efficiency to drop 90 percent of its initial value when exposed to difficult conditions.

Protective layer

Northwestern’s Bin Chen, who co-led the study, said the researchers were working on the stability of perovskite solar cells for a long time.

Chen pointed out that most reports focus on improving the stability of the perovskite material itself, without considering protective layers.
“By improving the protective layer, we were able to improve the overall performance of perovskite solar cells,” Chen added.

Perovskites are a family of materials that have shown potential for high performance and low production solar cell costs. The name “perovskite” comes from their crystal structure.

These materials are used in other energy technologies, such as fuel cells and catalysts. Perovskites commonly used in photovoltaic (PV) solar cells are more specifically called “metal halide perovskites” because they are made of a combination of organic ions, metals, and halogens; perovskites in other applications may consist of oxygen instead of halogens and are usually entirely inorganic.

Thermal stability of passivation layers

The new study, published in the journal Science, highlights the development of a library of amidinium ligands to increase thermal resistance. stability passivation layers on perovskite surfaces.

This strategy resulted in a >10-fold reduction in the ligand deprotonation equilibrium constant and a two-fold increase in maintaining photoluminescence quantum yield after aging at 85°C under illumination in air, according to the study. .

Northwestern’s Mercouri Kanatzidis, who co-led the study, said the new research addresses one of the critical obstacles to widespread adoption of perovskite solar cells: stability in real-world conditions.

Significantly advanced durability

“By chemically strengthening the protective layers, we have significantly improved the durability of these cells without compromising their exceptional efficiency, bringing us closer to a practical, low-cost alternative to silicon-based photovoltaics,” Kanatzidis said.

The researchers also pointed out that cutting-edge perovskite solar cells typically feature ammonium ligands as a passivation layer. However, ammonium tends to decompose under heat stress.

They did chemistry to convert unstable ammonium into more stable amidinium.

“Researchers carried out this conversion through a process known as amidination, in which the ammonium group is replaced with a more stable amidinium group. This innovation prevented perovskite cells from breaking down over time, especially when exposed to extreme heat,” said a press release.

The researchers argued that the resulting solar cell achieved an impressive efficiency of 26.3%, meaning it managed to convert 26.3% of absorbed sunlight into electricity.

The coated solar cell also retained 90% of its initial efficiency after 1,100 hours of testing under harsh conditions, demonstrating T90’s lifespan three times longer than before when exposed to heat and light, according to study.