| Abstract [eng] |
Search for new organic semiconductors has been of interest for many years. These compounds are used in optoelectronic devices such as organic light emitting diodes. Compounds for organic light emitting diodes should possess high stability, high luminescence quantum yield, good transport properties of both holes and electrons and to be able to exploit both singlet and triplet excitons. New naphtylcarbazole based compounds with different donor moieties were synthesized by Ullmann coupling. Thermal properties were investigated by differential scanning calorimetry and thermogravimetric analysis. The synthesized compounds display high thermal stability with 5 % weght loss temperatures exceeding 385 ºC. Majority of the synthesized compounds can exist as amorphous solids. Optical properties of naphtylcarbazole based compounds were investigated by UV-VIS and fluorescence spectroscopies. Compounds absorb electromagnetic radiation in the range of 210–450 nm. Thin films of the compounds emit in blue and purple region. Electrochemical stability of the compounds were studied by cyclic voltammetry. All compounds were found to be electrochemically stable except compound with 9,9-dimethyl-9,10-dihydroacridine moieties. Ionization potencials of the compounds estimated by cyclic voltammetry and are located in energy range from 5.0 to 5.4 eV. Using 3,6-di(4,4’-dimethoxydiphenylaminyl)-9-(1-naphtyl)carbazole as an emitter or in other cases as holes-transporting material, organic light-emitting diodes were fabricated. Device with 3,6-di(4,4’-dimethoxydiphenylaminyl)-9-(1-naphtyl)carbazole as an emitter showed external quantum efficiency of 3,3%. |
