Shulou(Shulou.com)05/31 Report--

Scientists have discovered an unexpected reason for the poor performance of a new type of flexible cheap solar cells, which brings them closer to the market.

Solar cells are part of photovoltaic solar panels. They are made of light-absorbing materials that convert sunlight into electricity. Usually this light-absorbing material is silicon, and its manufacturing process requires a lot of energy.

In the new study, scientists observed solar cells made of perovskite materials. The production cost of these materials is very low by mixing chemicals into printable or sprayable inks and then crystallizing to form light-absorbing films.

However, perovskite films contain charged defects, which may damage their properties. The slow movement of these defects is thought to be the cause of a process called hysteresis, which leads to the irregular efficiency of converting light into electricity.

Light is released from solar cells in the form of electrons for use. This is achieved through "contact lenses" sandwiched between light-absorbing films. Previously, scientists have successfully eliminated hysteresis by using more "selective" contact materials to ensure that electrons flow out of solar cells in one direction.

In theory, changing these contact materials should not have any effect on the motion of charged defects in perovskite, so why it seems to "repair" the hysteresis problem remains a mystery.

Now researchers and collaborators at Imperial College London have developed new experiments to track the direction of electrons in solar cells under short pulses of light.

They found that even in solar cells with very effective contact materials, mobile charging defects still exist, although these cells do not show lag. Hysteresis occurs only when the battery is affected by both defects and poor selectivity of contact points. The findings are published today in the journal Nature Communications.

Dr Pierce Barnes, from the physics department at Imperial College London, led the study. "in the past, people have been debating whether electrification defects or contact with materials caused the delay," he said. It's a bit like Agatha Christie's murder of the Orient Express, and we've proved that they both "did it".

"amazing progress has been made in this area. by reducing contact problems, we are on the right track. however, the results also show that improving contact is only part of the solution, and we still need to focus on the movement of charged defects in perovskite."

Charged defects may provide chemical weaknesses, leading to the final degradation of perovskite films. This raises potential concerns about the long-term stability of solar cells.

"the new technology we designed will enable communities to assess the mobility of charged defects, which will contribute to future research, improve stability, and bring the technology to market," Dr. Barnes said. "

The reason for the lag has been found, and there are still some challenges to overcome before perovskite solar cells can be commercialized. At present, one of the problems with perovskite is that it contains a small amount of lead in its chemical structure. Before it is considered safe on a larger scale, it may be necessary to find an alternative metal.

Scientists must also replicate their laboratory results with life-size solar panels. However, the key challenge will be to find a way to improve the long-term stability of perovskite materials.

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