Homogenized halides and alkali cation segregation in alloyed organic-inorganic perovskites
The role of the alkali metal cations in halide perovskite solar cells is not well understood. Using synchrotron-based nano–x-ray fluorescence and complementary measurements, we found that the halide distribution becomes homogenized upon addition of cesium iodide, either alone or with rubidium iodide, for substoichiometric, stoichiometric, and overstoichiometric preparations, where the lead halide is varied with respect to organic halide precursors. Halide homogenization coincides with long-lived charge carrier decays, spatially homogeneous carrier dynamics (as visualized by ultrafast microscopy), and improved photovoltaic device performance. We found that rubidium and potassium phase-segregate in highly concentrated clusters. Alkali metals are beneficial at low concentrations, where they homogenize the halide distribution, but at higher concentrations, they form recombination-active second-phase clusters.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Excitonics (CE); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Purdue Univ., West Lafayette, IN (United States); Univ. of California, San Diego, CA (United States)
- Sponsoring Organization:
- California Energy Commission (United States); National Science Foundation (NSF) (United States); USDOE; USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- AC02-06CH11357; SC0001088
- OSTI ID:
- 1528643
- Alternate ID(s):
- OSTI ID: 1493911
- Journal Information:
- Science, Journal Name: Science Journal Issue: 6427 Vol. 363; ISSN 0036-8075
- Publisher:
- American Association for the Advancement of Science (AAAS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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