Mystery that was holding back development of next-generation solar cells solved

Scientists have identified an unexpected cause of poor performance in a new class of flexible and cheap solar cells, bringing them closer to market.

In the new study, scientists looked at solar cells made from materials known as perovskites. These can be produced cheaply from chemicals mixed into printable or sprayable ink, which then crystallises to form light-absorbing films.

However, perovskite films contain charged defects that are likely to impair their performance. Slow movement of these defects is thought to be responsible for a process known as hysteresis, which leads to irregularities in the efficiency with which light is converted to electrical current.

Now researchers from Imperial College London and collaborators have developed new experiments to follow which direction electrons move in the solar cell when they are generated with a short pulse of light. They found that the mobile charged defects are still present even in solar cells with very efficient contact materials, despite these cells showing no hysteresis. Hysteresis was only found when cells suffered the combined effects of both the defects and poor selectivity at the contacts.

Read more at Imperial College London

Image Credit: Imperial College London

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