Synthesis and optical characterization of new highly luminescent poly(m,p-phenylenevinylene) derivatives

Poly(phenylenevinylene) (PPV) derivatives consisting of alternating,m-pheny lenevinylene and p-phenylenevinylene units were synthesized using the Witti g and the Wittig-Horner reactions. P1 which was prepared by the Wittig meth od contained both cis and trans double bonds in significant amounts. P2 was prepared by the Wittig-Homer reaction. Its vinylene configuration was near ly exclusively trans (> 35%). The m-linkages reduced the pi -conjugation le ngth in an effective way leading to blueshifted UV-Vis absorption and PL em ission spectra compared to analogous previously described PPV derivatives w ithout m-phenylenevinylene units. A dependence of solubility, film forming properties, molecular weight and optical spectra on the amount of substitue nts per repealing unit was observed. A LED fabricated from P2 exhibited low threshold voltages for the electroluminescence (4,3V) and high luminance(1 000 cd/m(2) at 10V).