A semiconductive copper iodobismuthate hybrid: structure, optical properties and photocurrent response.

Pursuits of new types of Pb-free heterometallic halides adequate for photovoltaic applications are still urgent but challenging. In this study, by using in situ -produced [(Me) 2 -(DABCO)] 2+ (DABCO = 1,4-diazabicyclo[2.2.2]octane; Me = methyl) cations as structure-directing agents, we successfully constructed a non-perovskite copper iodobismuthate hybrid, namely [(Me) 2 -(DABCO)] 2 Cu 2 Bi 2 I 12 (1), which features discrete [Cu 2 Bi 2 I 12 ] 4- anionic moieties formed by the building units of [CuI 4 ] tetrahedra and [BiI 6 ] octahedra. UV-Vis diffuse reflectance analyses showed that compound 1 possesses semiconductive behaviors with a narrow optical bandgap of 1.80 eV. More importantly, it exhibits excellent photoelectric switching abilities, and its photocurrent density (2.30 μA cm -2 ) far exceeds those of some high-performance halide-based counterparts. Different from many heterometallic analogues, noteworthily, it also has dispersive band structure and strong electronic coupling near the Fermi level, resulting in a material with small effective masses that may be responsible for the good photoelectricity. This study may offer new guidance for the design and synthesis of eco-friendly heterometallic halides with unique structures and desirable properties.