Two-dimensional semiconducting Cu(I)/Sb(III) bimetallic hybrid iodides with a double perovskite structure and photocurrent response

Discrete Hexa- and Binuclear Heterometallic Iodobismuthate(III) Complexes with Cu(I) and Ag(I)

The rare examples of discrete anionic halobismuthates(III) with group 11 elements were obtained. Those are (3-MePyH)6[Bi4Cu2I20] (1) and (3,5-MePyC6)3[BiAgI7]2 (2) (3-MePyH = 3-methylpyridinium cation, 3,5-MePyC6=1,6-bis(3,5-dimethylpyridinium)hexane dication). Both complexes were isolated as pure phases; the optical band gaps for 1 and 2 are 1.75 and 2.23 eV, respectively.

Ternary Complexes of BiI3/CuI and SbI3/CuI with Tetrahydrothiophene

Reactions of BiI3/CuI mixtures with tetrahydrothiophene (THT) in toluene produce 2-D sheet networks BiCu3I6(THT)n (n = 2, 3, or 4), depending on reaction conditions. All three structures are based on BiI6 octahedra, which share pairs of (μ2-I)2 with Cu3(THT)n units. BiCu3I6(THT)2 features Cu2(μ2-I)2 rhombs with close Cu···Cu interactions and is accompanied by formation of the very complex HBi3Cu12I22(THT)8. Reactions of SbI3/CuI with THT in toluene produced a SbCu3I6(THT)2 network shows Cu3(μ2-THT)2 units, like its Bi congener, but Cu6(μ2-I)6 barrels rather than rhombs. Isolated SbI3 units are stacked above the Cu6I6 barrels. A molecular compound, Sb3Cu3I12(THT)6 consists of a face-sharing Sb3I12 stack, in which the Cu-THT units are bonded in asymmetric fashion about the central SbI6. Metal-halide bonds were investigated via QTAIM and NLMO analyses, demonstrating that these bonds are largely ionic and occur between the Bi/Sb and I p orbitals. Hirshfeld analysis shows significant H···H and H···I interactions. Diffuse reflectance spectroscopy (DRS) reveals band edges for the Bi species of 1.71-1.82 eV, while those for the neutral Sb complexes are in the range of 1.94-2.06 eV. Mapping of the electronic structure via density of state calculations indicates population of antibonding Bi/Sb-I orbitals in the excited state.

Phase Transition and Luminescent Property Change Induced by Different Organic Cations in One-Dimensional Double Perovskites

Double perovskites (DPs) have attracted attention in the field of luminescence due to their inherent broadband emission of self-trapping excitons. In this work, we choose [(CH3)3NCH2CHCH2]+ and [CH3CHOHCH2NH2]+ as organic cations to synthesize two new organic-inorganic hybrid DPs, [(CH3)3NCH2CHCH2]2KInCl6 (1) and [CH3CHOHCH2NH2]2KInCl6 (2). The [KCl6]3- and [InCl6]3- octahedra are interchangeably connected by sharing two opposite faces, forming a one-dimensional coordination chain. Each K atom coordinates with six chlorine atoms in 1, while it coordinates with two oxygen atoms in addition to the six chlorine atoms in 2. The coordination between ions K and O in compound 2 may have significantly reduced its luminescence. As a result, compound 1 shows bright-yellow light with a quantum yield of more than 90%, while 2 shows weak blue light with a quantum yield of only 0.98%. In addition, different from no phase transition found in 2, 1 undergoes a reversible phase transition at 324/307 K in the heating-cooling cycle. Through structural and spectral analysis and density functional theory calculation, we conclude that the larger degree of [InCl6]3- octahedral distortion and the larger anion distance (In···In) also cause the PLQY of compound 1 to be higher than that of compound 2.

Fine Tuning Ag(I)-Sb(III) Hybrid Iodides for Light Detection

Lead-free hybrid double perovskite iodides (HDPIs) have piqued increasing research interest due to their environmental friendliness and high stability. However, such antimony-based HDPIs with strong photocurrent response are currently very limited. Here, we successfully design and construct five Ag(I)-Sb(III)-based HDPIs using two types of cyclic aliphatic amines as A-site templates. Interestingly, these Ag(I)-Sb(III) HDPIs exhibit relatively narrow band gaps, preferred orientation, and high stability after being processed into thin films on the indium tin oxide (ITO) substrate. Notably, under illuminations of a xenon lamp, all HDPIs exhibit considerable photocurrent responses, reaching a maximum difference of 17 μA·cm-2 for ASI 1, which is the highest among lead-free halogen-based organic-inorganic hybrid compounds to date. Combining the considerable photocurrents and the high stability, the optoelectronic applications of two-dimensional Ag(I)-Sb(III) HDPIs can be expected.