A research group at FAU and the Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN) have worked on a design aimed at significantly increasing the operational stability and life span of perovskite solar cells. Their design is based on a bilayer of polymers that protects the perovskites from corrosion at the same time as allowing uninterrupted charge transfer.
Until now, despite perovskite solar cells' potential, two major disadvantages have become apparent. Firstly, they do not have a particularly long life span, as perovskites tend to corrode on their interfaces and their performance capacity sinks rapidly, sometimes within days. Secondly, perovskite modules are not particularly robust in elevated temperatures, which severely limits their stability in practical use scenarios. This is mainly down to the layers doped with ions that are required for transporting the charge carriers but that can also lead to undesired secondary reactions.
"This architecture helps protect the extremely sensitive perovskite interface, whilst at the same time demonstrating an extraordinarily high conductivity, even at elevated temperatures", according to Dr. Yicheng Zhao, who has made a major contribution to developing the new module.
The results reportedly indicated stability and lifespan the likes of which have not yet been attained for perovskite solar cells. The group of researchers operated the module for a total of 1400 hours at a temperature of 65° Celsius under an artificial sun, without observing any corrosion or reduction in performance.
Even after about 60 days, the solar cells in question still reached, on average, 99 percent of their peak efficiency. Zhao estimates that "under everyday conditions, it could be possible to reach up to 20,000 operating hours". "If so, the double layer structure could play a key role in the development of competitive planar perovskite solar cells".
The success of the group is based on research into high-throughput methods. The idea behind the concept is to automate the combined use of materials, processes and technologies and link them to methods from AI and big data. A total of 160 different types of perovskites were investigated in the described project alone. Together with other conductive and contact layers and doping alternatives, this can easily lead to several thousand combinations.
