Mixed halide hybrid perovskites, CH3NH3Pb(I1-x Br x )3, represent good candidates for low-cost, high efficiency photovoltaic, and light-emitting devices. Their band gaps can be tuned from 1.6 to 2.3 eV, by changing the halide anion identity. Unfortunately, mixed halide perovskites undergo phase separation under illumination. This leads to iodide- and bromide-rich domains along with corresponding changes to the material's optical/electrical response. Here, using combined spectroscopic measurements and theoretical modeling, we quantitatively rationalize all microscopic processes that occur during phase separation. Our model suggests that the driving force behind phase separation is the bandgap reduction of iodide-rich phases. It additionally explains observed non-linear intensity dependencies, as well as self-limited growth of iodide-rich domains. Most importantly, our model reveals that mixed halide perovskites can be stabilized against phase separation by deliberately engineering carrier diffusion lengths and injected carrier densities.
Bibliographical noteKAUST Repository Item: Exported on 2022-06-08
Acknowledged KAUST grant number(s): OCRF-2014-CRG3-2268
Acknowledgements: This work was supported by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy under award DE-SC0014334. P.K. and S.Y. acknowledge support from the Division of Chemical Sciences, Geosciences, and Biosciences under award DE-FC02-04ER15533, Office of Basic Energy Sciences, U.S. Department of Energy. We also acknowledge ND Energy at the University of Notre Dame for seed funding. J.M. acknowledges support of King Abdullah University of Science and Technology (KAUST) through the Award OCRF-2014-CRG3-2268. We also thank the ND Colleges of Science and Engineering for financial support. This is contribution number NDRL No. 5138 from the Notre Dame Radiation Laboratory.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)