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Abstract:
Electrochemiluminescence (ECL) experiments were carried out in acetonitrile electrolytes with platinum electrodes coated with poly(2,3-dibutoxy-1,4-phenylenevinylene), DB-PPV. By application of alternating anodic and cathodic potential steps, positive and negative polarons were produced in the polymer. The annihilation reaction resulted in ECL transients. Model calculations were conducted for analyzing the electron and ion transport processes in the deposit as well as the kinetics of the annihilation reaction. Very good agreement with the experiments was found when the charging of the interfacial double layer was taken into account. The annihilation reaction was concluded to proceed under diffusion control. The emission spectrum was found to have its maximum at 480 nm. This is a shift by -10 nm with respect to the fluorescence spectrum of DB-PPV in chloroform, and by -40 nm with respect to the electroluminescence spectrum observed from the solid-state. The ECL emission spectrum did not depend on the sequence in which the positive and negative polarons were formed, in agreement with the expectation for an ECL mechanism.
