Researchers design a 20.9%-efficient perovskite solar device that retains 99% of initial efficiency after 1,450 hours

Researchers from Germany's Forschungszentrum Jülich have developed a planar perovskite solar cell that reportedly reached over 1,400'hours of operational stability at elevated temperatures. The 20.9% efficient device was built without the ionic dopants or metal oxide nanoparticles that are commonly used to contact the cell, as these can be subject to secondary reactions at higher temperatures.

The scientists tested many different perovskite mixtures before choosing the perovskite material for the cell, giving great focus to their thermal stability, using a self-constructed, high-throughput screening platform.

The entire cell electrode was embedded in a sort of protective shell with a double-layer polymer structure, with the bottom side undoped and the top side doped with a non-ionic dopant, which is claimed to protect against degradation and, at the same time, ensures that the contact is maintained.

'This architecture protects the very sensitive interface to the perovskite and, on the other hand, it shows exceptionally stable conductivity, even at elevated temperatures,' the team emphasized. 'The dopant-free polymer provides an acid barrier between the perovskite and the acid-doped polymer.'

Under standard illumination conditions, the cell was able to operate for 1,450 hours at elevated temperatures of around 65 degrees Celsius and, at the end of the testing period, it still retained 99% of its original efficiency.

'Long-term prediction is always difficult but the perovskite solar cell we have now developed could certainly be operated for more than 20,000 hours, under normal circumstances,' said researcher Christoph Brabec.

Looking forward, the academics say they want to improve cell efficiency. 'With an efficiency of 20.9%, the tested cell does not yet fully exploit the potential. Twenty-four to 25% should be possible in the near future,' explained research co-author, Yicheng Zhao.