Self-repairing healing solar cells recovering in the dark of the night

(Nanowerk News) Perovskite solar cells degrade when exposed to sunlight, which results in decreasing performance over time. A new research project will examine how such solar cells could recover and self-repair at night.
"Electronic components, such as solar cells and LEDs, are made from semiconductor materials," says Ellen Moons, professor of Physics at Karlstad University. "Such materials form the basis of all electronics, computers, cell phones and screens."
Halide perovskite is a new type of semiconductor, which has gained a lot of attention for reaching high performance as solar cell material — despite being simple and energy efficient to manufacture. The drawback of perovskite solar cells is that the performance decreases over time. It would be extremely valuable, not least from an environmental perspective, if the solar cells could repair themselves. This may sound like science fiction, but self-repair has been observed in certain materials.

Research collaboration with Israeli universities

The research is conducted as a collaboration project between Karlstad University and Ben-Gurion University of the Negev and Weizmann Institute of Science in Israel. Metal halide perovskite is a new category of semiconductors that have been shown to possess a self-repairing ability. They can be used for highly efficient solar cells and LEDs.
One of the Israeli research teams have shown that metal halide perovskite solar cells, which degrade in sunlight, can rebuild their efficiency at night, when it’s dark.
The other Israeli research team exposed single crystals of lead-based metal halide perovskites to powerful lasers, which made them lose their ability glow. The researchers then found that the material regained its photoluminescence following some recuperation time in darkness. Even if these two observations — one in the solar cell’s thin, multicrystalline layer and the other one in single crystals — seem related, we still don’t know what the potential relation is between these two phenomena, or how it works.
"In order to understand the self-repair mechanics of these materials, we will participate in this project to examine various samples, with and without interfacial layers," says Ellen Moons. "We will examine the interfacial layers’ role in preventing ions to and degradation products from leaving the perovskite layer. These degradation products can then be recycled in order to reverse the process and repair the metal halide perovskites."
The collaborating research teams will use non-destructive analytical methods to determine which bonds in the material that undergo changes in the degradation and repair processes. They will also examine what effects these changes have on the electronic properties of the material.

Research for sustainable development and renewable energy

"In the long term, this project will lead the way towards new and sustainable semiconductor materials," says Ellen Moons. "The materials will be energy efficient to manufacture and they will be able to restore their properties following degradation. What we are now learning about self-repairing semiconductor electronics is expected to be of significant value in the development of future renewable energy sources, as well as the development of sustainable electronics."
Source: Karlstad University
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