| 초록 |
A novel luminescent polymer, poly(2-methoxy-5-[6'-{1-cyano-1'-phenyl-2-(4-phenoxy)-ethene}]-hexyloxy)-1,4-phenylenevinylene-alt-2,5-bis-(dodecyloxy)-1,4-phenylenevinylene) (MCN-PPV), was synthesized by Heck coupling reaction. The band gap figured out from the UV-visible spectrum and PL maximum of the polymer are 2.10 eV and 581 nm, respectively. EL maximum of the device based on single layer structure (ITO/MCN-PPV/Al) appeared at 588 nm. In PL and EL spectra, emission from the pendants was not observed. Single layer EL device based on MCN-PPV have an efficiency of 0.12 cd/A at 3.55 mA/mm2 (420 cd/m2 at 15.5 V), which is significantly higher than that of MEH-PPV (0.003 cd/A, at 3.65 mA/mm2) measured under the same conditions and same device structure. The HOMO and LUMO energy levels of the polymer main chain figured out from the cyclic voltammogram and the UV-visible spectrum are -4.99 and -2.89 eV, respectively. The estimated HOMO and LUMO energy levels of the pendant were -6.16 and -2.98 eV, respectively, which are lower than those of the main chain. The results provide evidences that the pendants in MCN-PPV block the injected holes from the anode and facilitate the injection of the electrons from the cathode. |
