Two semiconductive haloargentates with metal-complex cations: Crystal structures, band gaps, photocurrent responses and theoretical investigations

Constructions of new haloargentate hybrids with semiconductor natures and photoelectric performances remain very fascinating yet challenging. In this paper, using in situ-generated [Co(2,2-bipy)3]2+ and [Ni(2,2-bipy)3]2+ metal-complex cations as the structure-directing agents, we successfully fabricated two new numbers of haloargentate family, namely [NH4][Co(2,2-bipy)3]2Ag6I11 (1) and [NH4][Ni(2,2-bipy)3]2Ag6Br11 (2). Two compounds are structurally isomorphic and contain the two-dimensional [Ag6X11]n5n− (X = I, Br) anionic layers that are perforated with large hexagonal windows. Optical properties show that compounds 1 and 2 exhibit the optical band gaps of 1.75 and 2.84 eV, respectively, demonstrating the visible-light responsive semiconductor behaviors. Under the alternating light irradiation, two as-synthesized materials possess the good photoelectric conversion abilities, with the observed photocurrent densities (0.20 and 0.22 μA cm⁻² for 1 and 2) comparable with many excellent metal halide competitors. Further density functional theory calcualtions disclose that the photosensitive metal complexes serve as the key factor in the charge transfer and carrier transport that may ultimately result in the satisfying photoelectric performances. Additionally, Hirshfeld surface analyses, thermogravimetric studies, and X-ray photoelectron spectroscopy characterizations of title compounds were also conducted in this work.