The optoelectronic properties of polymers containing Fluorene and Carbazole in nano environment

• Main Authors: Jian-Shin Liou, 劉建欣
• Other Authors: Yun Chen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/51566033670011383293

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 92 === 　　Since the discovery of electroluminescence(EL) in the poly(1,4-phenyl-enevinylene) (PPV) in 1990, EL conjugated polymers have attracted much interest in recent years because of their potential application in large-area flat panel displays. 　　In the past decade, fluorene-based conjugated polymers (PFs) have emerged as a very promising class of blue-light emitting materials for use in PLEDs because of their high photoluminescence (PL) and electro- luminescence quantum efficiencies, thermal stability, good solubility, and facile functionalization at the C-9 position of fluorene. However, the application of polyfluorenes in PLEDs has been hampered because of the troublesome formation of a tailed emission band at long wavelengths during device fabrication and operation, leading to both color instability and reduced efficiency. 　　In this study, we prepared a series of alternating fluorene/carbazole copolymers and systematically investigated the influences of the carbazole content on photophysical, electrochemical, and electroluminescent properties of the resulting polymers. Cyclic voltammetric studies have shown that the HOMO energy levels of copolymers can be raised by inducing the carbazole content. The copolymers exhibited stable PL spectra independent of annealing. However, their EL spectra showed significant red-shift with increasing operating voltage. 　　The polymers were also intercalated into　montmorillonite to investigate their physical, electrochemical, and optical properties. We found the nano- composites’s PL spectra are nearly the same as their corresponding polymers. However, annealing of the nanocomposite leads to appearance of new red-shifted peak, which is attributable to excimer formation. The nanocomposite of polyfluorene and montmorillonite shows more voltage- independent EL spectra when fabricated as ITO/PEDOT/Polyfluorene/Al device.