Air-Stable Direct Bandgap Perovskite Semiconductors: All-Inorganic Tin-Based Heteroleptic Halides Ax SnClyIz (A = Cs, Rb)
- Tsinghua Univ., Beijing (China); Northwestern Univ., Evanston, IL (United States)
- Northwestern Univ., Evanston, IL (United States)
- Northwestern Univ., Evanston, IL (United States); Seoul National Univ. (Korea, Republic of)
- Tsinghua Univ., Beijing (China)
Semiconducting halide perovskites are a group of materials with exciting photoelectronic properties. Compared to the widely studied hybrid organic–inorganic perovskites, the all-inorganic derivatives are less well understood even as they promise high inherent stability. At the moment, such materials are limited due to the fact that there is a very narrow choice of inorganic cations that can stabilize the desirable perovskite structure. Herein we report on the synthesis and characterization of novel all-inorganic tin-based perovskites and perovskitoids that can be stabilized by the heteroleptic coordination of chloride and iodide anions, Cs2SnCl2I2 (1) and Cs2.38Rb1.62Sn3Cl8I2 (2), consist of two-dimensional (2D) layers of [SnCl4I2]4– octahedra with different connectivity modes. Compound 1 is an n = 1 Ruddlesden–Popper type perovskite adopting the tetragonal archetype structure (I4/mmm space group; a = 5.5905(3) Å, c = 18.8982(13) Å), while compound 2 crystallizes as an orthorhombic modification (Cmcm space group; a = 5.6730(11) Å, b = 25.973(5) Å, c = 16.587(3) Å) with corrugated layers. The crystal chemistry changes drastically when Cs+ is replaced by the smaller Rb+ cation which leads to the isolation of the low dimensional compounds Rb3SnCl3I2 (3a), Rb3SnCl2.33I2.67 (3b) and Rb7Sn4.25Cl12I3.5 (4), thus illustrating the importance of the A-cation size in the formation of perovskites. The 2D perovskites show wide band gaps and relatively large resistivities, associated with their chemical stability against the oxidation of Sn2+. The chemical stability is coupled with remarkable electronic properties that derive from the perovskite structure. DFT calculations suggest that both compounds are direct band gap semiconductors with large bandwidths, consistently with the experimentally determined band gaps of Eg = 2.62 and 2.81 eV for 1 and 2, respectively. The combination of stability and favorable electronic structure in heteroleptic-halide perovskites presents a new direction toward the realization of functional devices made exclusively from inorganic perovskites.
- Research Organization:
- Univ. of California, Santa Barbara, CA (United States); Univ. of California, Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Science Foundation (NSF); National Natural Science Foundation of China (NSFC); Keck Foundation; Chinese Scholarship Council (CSC)
- Grant/Contract Number:
- SC0012541; NNCI-1542205; DMR-1121262; AC02-05CH11231
- OSTI ID:
- 1599735
- Journal Information:
- Chemistry of Materials, Vol. 30, Issue 14; ISSN 0897-4756
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Strong thickness-dependent quantum confinement in all-inorganic perovskite Cs 2 PbI 4 with a Ruddlesden–Popper structure
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journal | January 2019 |
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