The Optical Band-Gap Evolution in Perovskite-Like Hybrid Iodobismuthates Effected by Nuclearity and Dimension: An Experimental and DFT Calculation Study

Autor: You-Yu Wang, Wenxiang Chai, Dan-Dan Wang, Hang-Yan Shen, Yu-Xiang Jiang, Xiaorong Wang, Guo Jiayu, Li Song
Rok vydání: 2019
Předmět:
Zdroj: Journal of Cluster Science. 30:1443-1454
ISSN: 1572-8862
1040-7278
DOI: 10.1007/s10876-019-01587-8
Popis: Three new perovskite-like hybrid iodobismuthates with two quaternary ammonium cations, namely (BnNEt3)3(Bi2I9) (1) (BnNEt3)4(Bi4I16) (2) and (n-Bu4N)2n(Bi4I14)n (3) (Bn = benzyl, n-Bu = n-butyl), have been synthesized by reacting BiI3 with the quaternary ammonium iodide in molar ratio 2:3 (1), 1:1(2), and 2:1 (3), respectively. All hybrids were characterized by elemental analysis, X-ray diffraction and UV–Vis spectroscopic analysis. Single-crystal X-ray diffraction revealed that hybrids 1 and 2 are di-nuclear and tetra-nuclear cluster structures respectively, while 3 is a polymeric chain structure based on a (Bi4I14) tetra-nuclear cluster unit. Their optical band-gaps have been determined as 2.19 eV(1), 2.16 eV(2), 2.02 eV(3), respectively. The optical band gaps exhibit a structure-related decrease from 1 to 3, in agreement with their color changes and the density functional theory (DFT) calculation results. The DFT calculations also reveal that there is a inversely proportional relationship between the optical Eg and the aggregation degree of the BiI6 octahedra in the hybrid iodobismuthate clusters.
Databáze: OpenAIRE
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