Perovskite is a material that could be the next big thing in the solar industry. Researchers have now discovered how to heal defects in the molecular structure of the material by simply exposing it to the right amount of light and humidity. This kind of healing was demonstrated last year but then, the effects were only temporary. Now, after an extended period of research, a collaboration of experts from Cambridge, MIT, Bath, Oxford, and Delft have found a way to permanently heal these defects.

The concoction of light with water and oxygen molecules leads to substantial defect-healing in metal halide perovskite semiconductors. – Dr. Matthew T. Klug

Perovskite-based solar cells are already a good match for their silicon rivals.  But this new discovery could give them the upper hand. Silicon-based solar cells are still costly to produce and take a lot of energy in which to produce them. Perovskite-based solar panels are a great alternative as in comparison they’re relatively cheap and easy to produce, and in just a short space of time have managed to become almost as efficient as silicone ones.

The main thing that’s been affecting the efficiency and consistency of perovskites is tiny defects in their crystalline structure, called traps. These traps can become a bit of an obstruction for electrons and they often get stuck before they’ve had a chance to harness any energy. If electrons are able to move freely around a solar cell material, they will be much more efficient at converting light into electricity. The leader of the research and Marie Curie Fellow at both MIT and Cambridge University, Dr. Sam Stranks, advised, “In perovskite solar cells and LEDs you tend to lose a lot of efficiency through defects. We want to know the origins of the defects so that we can eliminate them and make perovskites more efficient.”

As part of the research, the team developed a perovskite-based device and exposed it to varying degrees of oxygen, humidity, and light. In doing this they discovered that perovskites begin to degrade as soon as they’re exposed to humidity. However, the strange thing is they found that when humidity levels reached between 40 and 50 percent and the exposure time was just 30 minutes, there was degradation. When researchers applied light to the device, a superoxide formed that prevented the traps from holding on to these electrons. When water is thrown into the mix, the perovskite surface transforms into a shell, removing traps but locking in the superoxide at the same time. This ensures that the improved performance of the perovskites is now a permanent one.

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