THE OPTICAL, ELECTRONIC, AND ELECTROLUMINESCENT PROPERTIES OF NOVEL POLY(P-PHENYLENE)-RELATED POLYMERS

A variety of novel, soluble, conjugated PPP- and PW-related polymers h ave been synthesized using a synthetic approach that allows for the ta iloring of the chemical structure of the polymer backbone. The absorpt ion and emission properties of the materials can be tuned over a wide range of the visible spectrum. The materials were characterized in ter ms of molecular weight and phase behavior. The localization of the ene rgy levels of the polymers has been determined with quantum mechanical calculations and experimentally with optical methods and cyclovoltame try. The mobilities of charge carriers measured in the microwave condu ctivity experiment are on the order of 10(-7) m(2)/(V . s) with an act ivation energy of ca. 0.06 eV. Photoluminescence (PL) quantum yields i n solution are generally higher than 60%; in the solid state values ev en of up to 73% are observed. If the conjugation is interrupted every tenth phenyl unit, mobilities are reduced by a factor of about 2 and P L efficiences are significantly increased. A range of electroluminesce nt devices partly containing additional electron- and hole-transportin g layers were also investigated. We obtain internal EL efficiencies of up to 4% in the blue region.