Optical properties and ab initio study on the hybrid organic–inorganic material [(CH3)2NH2]3[BiI6]

Crystal structure, vibrational and optical properties of a new self-organized material containing iodide anions of bismuth(III), [C6H4(NH3)2]2Bi2I10·4H2O

“…According to the literature, numerous bismuth iodide-based organic-inorganic materials ranging from the binuclear species (0-D) to long chain polymers (1-D) are studied, and extensive studies of the excitonic properties have been performed. In comparison with similar (0-D) inorganic bioctahedra structures, the exciton band in [C 6 H 4 (NH 3 ) 2 ] 2 Bi 2 I 10 Á4H 2 O occurs at substantially weaker energy (E ex = 2.4 eV) compared with those found in (AESBT) 3 Bi 2 I 9 (E ex = 2.49 eV) [6], (CH 3 NH 3 ) 3 Bi 2 I 9 (E ex = 2.51 eV) [35] and [(CH 3 ) 2 NH 2 ] 3 BiI 6 (isolated octahedron) (E ex = 2.6 eV) [36]. Note that the exciton band peak position is similar to that observed for the inorganic (1-D) chain structure (H 2 DDDA)BiI 5 (E ex = 2.41 eV) [2], and intermediate between (H 2 AETH)BiI 5 (E ex = 2.53 eV) [2] and (H 2 DAH)BiI 5 (E ex = 2.24 eV) [23], indicating that the band positions are substantially influenced by more than just the effective dimensionality of the inorganic framework.…”

“…Also, it was found that the band gap value increases from 2.48 eV in (H 3 N(CH 2 ) 6 NH 3 )BiI 5 (1-D) [23] to 2.84 eV in the present work, 2.9 eV in (CH 3 NH 3 ) 3 Bi 2 I 9 and 3.04 eV in [(CH 3 ) 2 NH 2 ] 3 BiI 6 (0-D). These results may be related to the zero-dimensional quantum-confinement effects [36], and apparently reflect the effect of the inorganic framework dimensionality on the electronic structure of the material [23].…”

Structural characterization, vibrational studies and optical properties of a new luminescent organic-inorganic material [C6H20N3]BiI6·H2O

“…The recombination of the electron and a hole in the exciton yields a red emission at 604 nm. The Stokes shift between absorption at 2.27 eV and the emission at 2.05 eV is rather large (220 meV) [31,35,36] and mainly due to the exciton binding energy and the low dimensional (0D) structure.…”

Comparative studies of vibrational properties and phase transitions in metal-organic frameworks of [NH4][M(HCOO)3] with M=Mg, Zn, Ni, Fe, Mn

“…Let us now discuss the effect of different type of divalent ion on wavenumbers of internal modes and hydrogen bond strength. The N-H stretching vibrations of free molecules are usually observed in the region 3300-3500 cm À1 [34,35]. When the N-H bonds participate in formation of hydrogen bonds, the stretching modes shift to lower wavenumbers and intensity as well as bandwidth of the corresponding bands increase [36].…”