Crystal Structure and Optical Properties Characterization in Quasi-0D Lead-Free Bromide Crystals (C 6 H 14 N) 3 Bi 2 Br 9 ·H 2 O and (C 6 H 14 N) 3 Sb 3 Br 12

• Published in: Inorganic chemistry 2024-03, Vol.63 (10), p.4747-4757
• Main Authors: Tang, Hao, Zheng, Pengfei, Xiao, Zhifeng, Yuan, Kejia, Zhang, Hanwen, Zhao, Xiaochen, Zhou, Wei, Wang, Shouyu, Liu, Weifang
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.4c00052

Low dimensional organic inorganic metal halide materials have shown broadband emission and large Stokes shift, making them widely used in various fields and a promising candidate material. Here, the zero-dimensional lead-free bromide single crystals (C H N) Bi Br ·H O ( ) and (C H N) Sb Br ( ) were synthesized. They crystallized in the monoclinic crystal system with the space group of 2 and 2 / , respectively. Through ultraviolet-visible-near-infrared (UV-vis-NIR) absorption analysis, the band gaps of (C H N) Bi Br ·H O and (C H N) Sb Br are found to be 2.75 and 2.83 eV, respectively. Upon photoexcitation, (C H N) Bi Br ·H O exhibit broad-band red emission peaking at 640 nm with a large Stokes shift of 180 nm and a lifetime of 2.94 ns, and the emission spectrum of (C H N) Sb Br are similar to those of (C H N) Bi Br ·H O. This exclusive red emission is ascribed to the self-trapping exciton transition caused by lattice distortion, which is confirmed through both experiments and first-principles calculations. In addition, due to the polar space group structure and the large spin-orbit coupling (SOC) associated with the heavy elements of Bi and Br of crystal , an obvious Rashba effect was observed. The discovery of organic inorganic metal bromide material provides a critical foundation for uncovering the connection between 0D metal halide materials' structures and properties.