Suppression of phase transitions and glass phase signatures in mixed cation halide perovskites
2Thomas Young Centre and Department of Materials, Imperial College London, London, UK
3Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland
4Department of Experimental Physics, Wroclaw University of Science and Technology, Wroclaw, Poland
Cation engineering provides a route to control the structure and properties of hybrid halide perovskites, which has resulted in the highest performance solar cells based on mixtures of Cs, methylammonium (MA), and formamidinium (FA). Here, we present a multi-technique experimental and theoretical study of structural phase transitions, structural phases and dipolar dynamics in the mixed MA1-xDMAxPbBr3 hybrid perovskites, where DMA denotes a dimethylammonium cation. Our results demonstrate a significant suppression of the structural phase transitions, enhanced MA disorder and stabilization of the cubic phase even for a small amount of DMA cations [1]. As the DMA concentration approaches the solubility limit in MAPbBr3, we observe the disappearance of the structural phase transitions and signatures of a glassy dipolar phase formation. We also reveal a significant tunability of the dielectric permittivity upon mixing of the molecular cations that arises from frustrated electric dipoles. We compared our findings to the related mixed cation perovskite system of MA1-xFAxPbBr3 [2] and MA1-xEAxPbI3.
Acknowledgements: This project has been funded by the Research Council of Lithuania (LMTLT) (agreement
No. S-MIP-19-4).
References
[1] Šimėnas et al. Nat. Commun. 11, 5103 (2020)
[2] Šimėnas et al. Chem. Mater. 33, 5926 (2021)
[3] Šimėnas et al. 10.26434/chemrxiv-2022-xd6cg (2022)
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