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- Wu, Hua, et al.
(author)
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Mixed-Halide Double Perovskite Cs2AgBiX6 (X=Br, I) with Tunable Optical Properties via Anion Exchange
- 2021
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 14:20, s. 4507-4515
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Journal article (peer-reviewed)abstract
- Lead-free double perovskites, A2M+M′3+X6, are considered as promising alternatives to lead-halide perovskites, in optoelectronics applications. Although iodide (I) and bromide (Br) mixing is a versatile tool for bandgap tuning in lead perovskites, similar mixed I/Br double perovskite films have not been reported in double perovskites, which may be due to the large activation energy for ion migration. In this work, mixed Br/I double perovskites were realized utilizing an anion exchange method starting from Cs2AgBiBr6 solid thin-films with large grain-size. The optical and structural properties were studied experimentally and theoretically. Importantly, the halide exchange mechanism was investigated. Hydroiodic acid was the key factor to facilitate the halide exchange reaction, through a dissolution–recrystallization process. In addition, the common organic iodide salts could successfully perform halide-exchange while retaining high mixed-halide phase stability and strong light absorption capability.
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