Electroluminescent properties of aromatic polyimides in the presence of organic luminophores

For aromatic polyimides containing cyanine dyes as dopants, the effect of t he energy characteristics of electroactive polymer medium and the redox pot entials (E-1/2(ox) and E-1/2(red)) of luminophores as impurity emitting cen ters on the electroluminescent properties of the system was studied. It was shown that electroluminescence can be generated for the dye molecules if t heir E-1/2(ox) and E-1/2(red) values correspond to the levels arranged with in the forbidden band at a certain distance from the highest occupied and t he lowest unoccupied orbitals of the polymer matrix. In the electroluminesc ence spectra of some of the systems studied, a band assigned to the emissio n of J-aggregates, which form the nanocrystalline phase of the dyes in the polymer, was first found. The electroluminescence spectrum of J-aggregates exhibits a narrow band shifted to longer wavelengths relative to the absorp tion spectrum of the monomeric form.