Synthesis And Properties Of Benzothiadiazole-based Donor-Acceptor Organic Optoelectronic Materials

Compared with the traditional inorganic photoelectrical materials, organic photoelectrical compounds present the potential of an excellent reproducibility of synthesis and purification. Recently, organic photoelectrical compounds have been successfully used in many optoelectronic devices, such as organic light emitting diodes, organic photovoltaics and organic memory devices. In this thesis, the performance of the materials could be well regulated mainly through the introduction of the alkyl thiophene units in several benzothiadiazole groups to triindole. The resulting molecules were systematically characterized by NMR, UV-vis and PL and so on.(1) A series of organic photoelectric conjugated molecules, which were based on several2,1,3-benzothiadiazole groups as the core and end-capped with alkyl thiophene units, were synthesized by Suzuki coupling reactions. Research results indicated that these small molecules possess broad absorption and high thermal stability. The absorbance spectral ranges of molecules were broaded effectively and the band gaps were reduced by modulating the effective conjugated chain length and changing the substitute position of alkyl chains.(2) A series of star-shaped conjugated molecules with triindole as the core, thiophene-benzothiadiazole units as the arms, have been designed and synthesized. The resulting molecules possess a series of advantages, such as high solubility, low band gap, broad absorption and good thermal stability. OLEDs were fabricated with this series of molecules as the dye and commercial small molecule MADN as the host material. Comparing the three devices, D2is an ideal organic light-emitting device, which has great relevance to the molecular structure of the light-emitting material.(3) A series of electrochemical deposition measurements were performed by CV mode. The absorption bands of the resulting polymers appeared visible red shift, indicating that the polymerizations had been formed. The surface morphology of the ED films was analyzed by scanning electron microscopy (SEM). The electrode surfaces were covered over by the polymeric structure materials, without distinctly hollow spaces. The disparities observed in SEM micrographs of the two ED films are connected with the length of conjugated chain in the molecular structures.