POLY(P-PHENYLENEVINYLENE) BY CHEMICAL-VAPOR-DEPOSITION - SYNTHESIS, STRUCTURAL EVALUATION, GLASS-TRANSITION, ELECTROLUMINESCENCE, AND PHOTOLUMINESCENCE

Poly (p-phenylenevinylene) (PPV) was prepared via chemical vapor depos ition (CVD) by vapor phase pyrolysis of alpha,alpha'-dihalogenated p-x ylenes or alpha,alpha-dihalogenated p-xylenes. Differences in the prod uct composition obtained are discussed. The advantages for the film fo rmation as well as the limitations are reported with respect to the fa brication of light-emitting diode (LED) cells. PPV films were characte rized by various techniques. They show a glass transition temperature at 220 degrees C, a hypsochromic shift of the S-1 --> S-0 transition a nd higher degree of disorder as compared to ordinary PPV. The current- voltage characteristics of LED cells with PPV prepared via CVD show an unusually high rectification ratio. In contrast to PPV annealed at lo wer temperatures the formation of an unidentified defect structure was detected by C-13 CP-MAS/TOSS spectroscopy with PPV films annealed at higher temperatures.