Study On Synthesis And Characterization Of Organic Terahertz Sensitive Materials

Terahertz (THz) technologies have attracted extensive attention owing to theirwide applications in optical imaging, safety monitoring, biomedicine, militarycommunication and so on. Among various THz technologies, uncooled THz detectorsbecome a research hotspot in recent years. However, the THz absorption response of thetraditional inorganic sensitive materials is rather weak, which can not meet theapplication requirements. Aiming at this problem, a new nonlinear organic material wassynthesized in this thesis, and the composite films were prepared. The ultraviolet visiblelight performance, thermistor performance, crystallinity and morphology of theas-prepared composite films were systematically studied. Finally, device parameters ofthese composite films applied in microbolometer were evaluated. The specific contentsare as follows:(1) Self-constructed a synthetic platform independently. A nonlinear organicmaterial DAST was synthesized by chemical method, and the products were purified.The product yield was over70%. The purified product was characterized by elementalanalysis, mass spectrometry,1H nuclear magnetic resonance test and Fourier infraredspectroscopy, which results demonstrated that the purified product is nonlinear organicmaterial DAST.(2) Basing on the excellent terahertz absorption characteristics of organic materialDAST, a new type of organic composite films were also prepared in this thesis. Bychange the content of multi-walled carbon nanotubes (MWCNTs) in the organiccomposite films, a series of DAST-MWCNTs composite films were successfullyprepared for systematic investigation on the electrical and optical properties. The resultsshowed that greatly increase of the absorption in the red and near-infrared bands wasobserved when multi-walled carbon nanotubes were added into the DAST films.Especially, the resistance value of composite films also decreased by3-9orders ofmagnitude, and the conductivity is greatly improved. Temperature coefficient ofresistance (TCR) decreased slightly and slowly if the content of MWCNTs>6.7wt.%. Crystallinity and morphology analyses proved the changes of microstructure inside thecomposite films, giving explanations on the changes of optical and electrical properties.(3) Investigated the electrical noise and thermal conductivity of DAST-MWCNTscomposite film materials, which were then compared with the traditional infraredmicrobolometer. Potential applications of such DAST-MWCNTs composite films onuncooled microbolometer were evaluated.