HALOGEN PRECURSOR ROUTE TO POLY[(2,3-DIPHENYL-P-PHENYLENE)VINYLENE] (DP-PPV) - SYNTHESIS, PHOTOLUMINESCENCE, ELECTROLUMINESCENCE, AND PHOTOCONDUCTIVITY

Thin films of poly[(2,3-diphenyl-p-phenylene)vinylene] (DP-PPV) have b een prepared via a chlorine precursor route (CPR). This involves the p olymerization of 1,4-bis(chloromethyl)-2,3-diphenylbenzene with 1.0 eq uiv of potassium tert-butoxide to give the chlorine precursor polymer of DP-PPV. The chlorine precursor was thermally converted at different temperatures to give DP-PPV with different degrees of conversion. The conversion process was monitored by in situ photoluminescent (PL) spe ctroscopy. The onset of conversion was about 150 degrees C, and full c onversion could be achieved at 170-250 degrees C. The degree of conver sion was a function of the heating temperature rather than the duratio n of heating. The fully converted DP-PPV showed lower photoconductivit y and higher PL intensity than PPV. Although partially converted DP-PP V showed bright FL, we have not been able to observe its EL. The elect roluminescence (EL) of the single layer ITO/DP-PPV/Mg and the bilayer ITO/DP-PPV/Alq(3)/Mg LED devices is also reported. A significant impro vement in the quantum efficiency (up to 0.7% ph/el) and a reduction in the turn-on voltage of the device were found upon incorporation of th e Alq(3) layer. These observations suggest that Alq(3) enhances the in jection of electrons and also participates in the recombination proces s.