Effect of End-capping Functional Groups on the Optoelectronic Properties of Oligothiophene Derivatives



Five novel oligothiophene derivatives end-capped by different functional groups (R=ethoxyl (EtOP3T), methylsulfanyl (MSP3T), acetyl (AcP3T), methylsulfonyl (MSO2P3T) and biphenyl (BP3T) groups) were synthesized. They were characterized by Hnuclear magnetic resonanceH (P1PH NMR), Hmass spectrometryH (MS) and Fourier transform Infra-red spectra (IR). The relationship between end-capping functional groups and optoelectronic properties of them was investigated. It was found that the compound with sulfonyl group in the molecular structure (MSOR2RP3T) shows the highest oxidation stability (also supported by theoretical calculations) and best thermal stability among the five compounds. The results of scanning electron microscope (SEM) interpret that MSOR2RP3T displays excellent ability of self-film forming. This reveals that it could be a potential candidate for thin film material. The liquid crystal property of MSOR2RP3T was characterized by polarized optical microscopy analysis (POM) and X-ray diffraction (XRD). The results of this paper provide useful information for the design of tailored oligothiophene derivatives for devices.