Structures And Properties Of Organic/inorganic Hybrid Semiconducting Materials Linked By Coordination Bonds

Organic-inorganic hybrid semiconductors may combine the advantages of organic and inorganic semiconductors and have been attracting more and more attentions. Several organic-inorganic hybrid semiconductors linked by coordination bonds between organic amine and metal halides were designed and synthesized in this dissertation. The structures, energy gaps, mechanism of the luminescence and the conductivity of thin films of these hybrid materials were studied in detail. The main content of this dissertation is as follows:1. By controlling the ratio of CdI2 and phenethylamine (PEA), CdI2(PEA)2 with one dimensional structure (1D) and CdI2(PEA)4 with zero (0D) dimensional structure were obtained. [CdI2(PEA)2](CdS)0.038 was obtained by doping CdS nanoparticles into the 1D matrixβ-CdI2(PEA)2. CdI2(PEA)2, CdI2(PEA)4, and [CdI2(PEA)2](CdS)0.038 exhibited bright blue, green, and orange fluorescent emissions in solid state at room temperature, respectively. Theoretical studies of electronic structures revealed that the emissions of CdI2(PEA)2 andβ-CdI2(PEA)2 were originated from halide-to-metal charge transfer (XMCT) while the emission of CdI2(PEA)4 was originated from halide-to-ligand charge transfer (XLCT).2. N-(2-aminoethyl)carbazole (AEC) was synthesized as the organic ligand and a new type of hybrid materials named as ZnCl2(AEC)2, ZnI2(AEC)2, CdI2(AEC)2, and HgI2(AEC)2 were obtained. The single crystals of ZnCl2(AEC)2?CH3CN and ZnI2(AEC)2?CH3CN were prepared from solution. Both of the packings of the crystals contained 1D structure. The energy gaps (Eg) of ZnCl2(AEC)2, ZnI2(AEC)2, CdI2(AEC)2, and HgI2(AEC)2 were close to the organic ligand AEC and independent of the inorganic portions. The fluorescent emissions of ZnCl2(AEC)2, ZnI2(AEC)2, and CdI2(AEC)2 exhibited characteristic emission peaks of carbazole. Theoretical studies of electronic structures revealed that the emissions of ZnCl2(AEC)2, ZnI2(AEC)2, and CdI2(AEC)2 were originated from the carbazole rings of the organic ligand. The thin-film conductivities of these hybrid materials were close to AEC and almost independent of the metal halides, indicating that the charge transport in these hybrid materials was merely through the carbazole rings of the organic ligand AEC.3. Acridine (AD) which has a large space hinder effect was introduced as the N-donor organic ligand into the hybrid materials. CdI2(AD) formed 1D structure while HgI2(AD) formed 0D structure. The energy gap of CdI2(AD) was also dependent on the organic ligand. There were no characteristic emission peaks of acridine in the fluorescent emissions of CdI2(AD). Theoretical studies of electronic structures revealed that the emission of CdI2(AD) was originated from halide-to-ligand charge transfer (XLCT). The conductivity of CdI2(AD) film was 2×10-5 Sm-1 which was very close to the inorganic portion CdI2 (3×10-5 Sm-1) and much higher than acridine. This result indicated the charge transport in CdI2(AD) was through the one dimensional structure of inorganic framework while the organic portion acridine assisted to the charge transport.