Researchers at the University of Potsdam, Humboldt-University of Berlin, University of Wuppertal, Swansea University, University of Oxford, East China University of Science and Technology, Friedrich-Alexander-University Erlangen-Nürnberg and HZB have shown that ion-induced field screening is a dominant factor in the operational stability of perovskite solar cells (PSCS).
The rather poor perovskite stability is usually attributed to electronic defects, electrode oxidation, the ionic nature of the perovskite, or chemical decomposition under moisture and oxygen. Understanding the underlying degradation mechanism is crucial to enable targeted improvements. "In our article, we demonstrate that an increasing concentration of defects in the cells is apparently not a decisive factor for degradation," says Martin Stolterfoht, former leader of the Heisenberg junior research group PotsdamPero at the University of Potsdam and now professor at the Chinese University of Hong Kong.
Instead, it is the creation of more and more mobile ions under external stressors in the perovskite semiconductors that screen the built-in field in the perovskite absorber which leads to charge extraction losses.
"We have shown that the ion-induced field screening dominates the operational stability of various commonly used perovskite cells. For example, we can use the ionic fingerprints detected in newly developed devices to accurately predict the stability of the cells," he adds.
These findings lay the foundation for new strategies to improve the cell lifetime and to accelerate the development of new perovskite cells with improved stabilities.
