Oral: Trends of ion migration barriers in metal halide perovskites*

The intrinsic instability caused by the ion migration in metal halide perovskites seriously limits the device stability and performance. While strategies, such as alloying, dimensionality reduction, and introduction of ionic additives, have been adopted to enhance stability in the metal halide perovskites, the roles of ion migration kinetics and the underlying controlling physical rules remain elusive. In this work, we provide a systematic, first principles study on trends in ion migration barriers concerning local structure environment and electronic structure factors. The migration barriers of Cs and halogen X in perovskites CsBX₃ (B = Pb, Sn; X = Cl, Br, I) were calculated using the climbing image nudged elastic band method. An analysis of the saddle image structure corresponding to Cs-site and X-site migration reveals that the structures are same, except for the compositional change. Interestingly, it is found that the migration barrier is highly correlated with changes in the integrated antibonding states below the Fermi level along the migration pathway.

 

Supported by NSF Award Number DMR-2127630