Ferroelastic twin domains in CH3NH3PbI3 (top) are under different strain conditions, resulting in a redistribution of mobile ions (bottom), thus forming the stripes of chemical segregation corresponding to twin domain structures.
Scientific Achievement
Ferroelastic twin domains in CH3NH3PbI3 (top) are under different strain conditions, resulting in a redistribution of mobile ions (bottom), thus forming the stripes of chemical segregation corresponding to twin domain structures. (hi-res image)
Multimodal functional and chemical imaging methods show that twin domains in CH3NH3PbI3 are due to correlated elastic variation and ion segregation.
Significance and Impact
The new understanding provides a roadmap for measuring, interpreting, and understanding the optoelectronic performance of related hybrid organic-inorganic perovskites.
Research Details
– The previously reported piezoelectric-like contrast of CH3NH3PbI3 twin domains is shown to be of mechanical nature (ferroelastic) rather than electromechanical.
– Chemical and two-photon polarization imaging highlight differences in chemical composition and crystallographic orientation of these ferroelastic twin domains.
– Density functional theory (DFT) provides a cohesive picture describing ferroelasticity, strain, and chemical segregation.
Y. Liu, L. Collins, R. Proksch, S. Kim, B. R. Watson, B. Doughty, T. R. Calhoun, M. Ahmadi, A. V. Ievlev, S. Jesse, S. T. Retterer, A. Belianinov, K. Xiao, J. Huang, B. G. Sumpter, S. V. Kalinin, B. Hu, and O. S. Ovchinnikova, "Chemical nature of ferroelastic twin domains in CH3NH3PbI3 perovskite," Nature Mater. (2018). DOI: 10.1038/s41563-018-0152-z
