Iodobismuthates Containing One-Dimensional BiI4– Anions as Prospective Light-Harvesting Materials: Synthesis, Crystal and Electronic Structure, and Optical Properties

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• 作者：Natalie A. Yelovik ; Andrei V. Mironov ; Mikhail A. Bykov ; Alexey N. Kuznetsov ; Anastasia V. Grigorieva ; Zheng Wei ; Evgeny V. Dikarev ; Andrei V. Shevelkov
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：May 2, 2016
• 年：2016
• 卷：55
• 期：9
• 页码：4132-4140
• 全文大小：497K
• 年卷期：0
• ISSN：1520-510X

文摘

Four iodobismuthates, LiBiI₄·5H₂O (1), MgBi₂I₈·8H₂O (2), MnBi₂I₈·8H₂O (3), and KBiI₄·H₂O (4), were prepared by a facile solution route and revealed thermal stability in air up to 120 °C. Crystal structures of compounds 1–4 were solved by a single crystal X-ray diffraction method. 1: space group C2/c, a = 12.535(2), b = 16.0294(18), c = 7.6214(9) Å, β = 107.189(11)°, Z = 4, R = 0.029. 2: space group P2₁/c, a = 7.559(2), b = 13.1225(15), c = 13.927(4) Å, β = 97.14(3)°, Z = 2, R = 0.031. 3: space group P2₁/c, a = 7.606(3), b = 13.137(3), c = 14.026(5) Å, β = 97.14(3)°, Z = 2, R = 0.056. 4: space group P2₁/n, a = 7.9050(16), b = 7.7718(16), c = 18.233(4) Å, β = 97.45(3)°, Z = 4, R = 0.043. All solid state structures feature one-dimensional (BiI₄)⁻ anionic chains built of [BiI₆] octahedra that share two opposite edges in such a fashion that two iodine atoms in cis-positions remain terminal. The calculated electronic structures and observed optical properties confirmed that compounds 1–4 are semiconductors with direct band gaps of 1.70–1.76 eV, which correspond to their intense red color. It was shown that the cations do not affect the optical properties, and the optical absorption is primarily associated with the charge transfer from the I 5p orbitals at the top of the valence band to the Bi 6p orbitals at the bottom of the conduction band. Based on their properties and facile synthesis, the title compounds are proposed as promising light-harvesting materials for all-solid solar cells.