期刊
NANO LETTERS
卷 18, 期 6, 页码 3502-3508出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.8b00560
关键词
Lead-free halide perovskites; double perovskites; cesium silver bismuth halides; perovskite nanocrystals
类别
资金
- U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division within the Physical Chemistry of Inorganic Nanostructures Program [DE-AC02-05-CH11231, KC3103]
- Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy [DE-AC02-05CH11231]
- Sackler Fellowship
- National Science Foundation Graduate Research Fellowship under DGE [1752814]
- Future Scientist Postdoctoral Fellowship by China Scholarship Council [201506150112]
- Direct For Education and Human Resources [1752814] Funding Source: National Science Foundation
- Division Of Graduate Education [1752814] Funding Source: National Science Foundation
Replacing lead in halide perovskites is of great interest due to concerns about stability and toxicity. Recently, lead free double perovskites in which the unit cell is doubled and two divalent lead cations are substituted by a combination of monoand trivalent cations have been synthesized as bulk single crystals and as thin films. Here, we study stability and optical properties of all-inorganic cesium silver(I) bismuth(III) chloride and bromide nanocrystals with the double perovskite crystal structure. The cube-shaped nanocrystals are monodisperse in size with typical side lengths of 8 to 15 nm. The absorption spectrum of the nanocrystals presents a sharp peak, which we assign to a direct bismuth s-p transition and not to a quantum confined excitonic transition. Using this spectroscopic handle combined with high-resolution transmission electron microscopy (TEM) based elemental analysis, we conduct stoichiometric studies at the single nanocrystal level as well as decomposition assays in solution and observe that Ag+ diffusion and coalescence is one of the pathways by which this material degrades. Drying the nanocrystals leads to self-assembly into ordered nanocrystal solids, and these exhibit less degradation than nanocrystals in solution. Our results demonstrate that Cs2AgBiX6 (X = Cl, Br) nanocrystals are a useful model system to study structure-function relationships in the search for stable nontoxic halide perovskites.
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