| Abstract [eng] |
Technology of organic light-emitting diodes became one of the fastest growing technologies used in the fabrication of displays due to the small energy consumption, large viewing angles and self-emission. Today, organic light-emitting diodes are widely commercialized in television or phone displays, yet all their potential has not been reached as their external quantum efficiencies are still below the target values. The development of new materials with superior properties, which would allow the construction of increasingly efficient devices, is essential for the further growth of this technology. The rapidly evolving technology of organic light-emitting diodes has displayed that it is possible to approach 100 % internal quantum efficiency by dispersing phosphorescent emitters in suitable host materials or by using materials exhibiting thermally activated delayed fluorescence. In this work, four new trifluoro benzonitrile containing indolocarbazoles displaying aggregation enhanced thermally activated delayed fluorescence were synthesized and characterized. Thermal, photophysical and electrochemical properties of objective materials were investigated by the experimental and theoretical tools. All the synthesized materials displayed high thermal stability and all compounds can exist in the solid amorphous state. Studies of photoluminescence spectra of the dispersions of the compounds in tetrahydrofuran-water mixtures showed that the synthesized indolocarbazole derivatives exhibited aggregation enhanced emission. Steady-state and time-resolved photoluminescence measurements of deoxygenated and air equilibrated toluene solutions performed at the different temperatures revealed thermally activated delayed fluorescence. An increase in photoluminescence quantum yield to 68 % has been observed after removal of oxygen from toluene solutions of the compounds. Effective emission with photoluminescence quantum yields up to 58 % was also recorded for solid films of the pure products. The synthesized compounds were used in organic light-emitting diode prototypes as host materials and emitters. External quantum efficiency of 2.22 %, power efficiency of 2.28 lm/W and current efficiency of 6.59 cd/A were observed for the device containing light emitting layer of the synthesized compound. Overall best performance was displayed by the device fabricated using target compounds as host materials for thermally activated delayed fluorescence emitter. It showed external quantum efficiency of 11.09 %, power efficiency of 12.24 lm/W, and current efficiency of 12.24 cd/A. Based on the research of the master’s final project, a recommended technological scheme for the production of indolocarbazoles containing trifluoro benzonitrile acceptor moieties was developed, work safety was described, and the hazards of the used materials were assessed. |
