Synthesis and spectral characterizations of electroluminescent poly(2,3-di-[p-(2′-ethylhexoxy)phenyl]-1,4-phenylenevinylene)

By means of chemical modification, flexible branched alkoxy chains were successfully attached to the para-site of the side phenyl groups of DP-PPV to obtain a new soluble fully conjugated PPV, named poly(2,3-di-[p-(2′-ethylhexoxy)phenyl]-1,4-phenylenevinylene). Spectroscopic characterizations using UV, photoluminescence (PL) and photoluminescent excitation (PLE) showed only the emission of single chromophore of this polymer in the solution state, indicating that the solubility of poly(2,3-diphenyl-1,4-phenylene vinylene) (DP-PPV) was significantly improved by attaching the alkoxy side chains. In the spin-coated film, the emission of the single chromophore with longer conjugating length was observed. In addition, the spectral feature showed the absence of the emission from the aggregate, which was usually observed in the alkoxy-modified PPV, revealing that the polymer chains were well-separated by the side chains. The performance of the single-layer ITO/PEDOT/p-EHDP-PPV/Ca/Al LED device was also reported. The maximum luminescence and efficiency at 11 V was 3735 Cd/m2 and 0.57 Cd/A, respectively.