EXCITATION-ENERGY TRANSFER IN SEGMENTED LADDER-TYPE POLY(PARA-PHENYLENE) BLUE-LIGHT-EMITTING DIODES

Light emitting diodes were fabricated in ITO/polymer/metal layer struc ture using A1 as metal electrodes and a derivate of poly(para phenylen e) (PPP) as the active layer. This novel polymer is a ladder-type PPP, segmented by a copolymer for enhanced quantum efficiency and soluble due to its side-groups. Bright blue emission, high quantum efficiency and easy processing make copolymers of this type promising materials f or technical optoelectronic device applications. We present results on electroluminescence, absorbance and photoluminescence and discuss pol ymer properties as well as possible recombination processes. We observ e the formation of excimer like states under the influence of an elect ric field and their radiative recombination giving electroluminescence emission in the wavelength region of about 580 nm.