| Abstract [eng] |
One of the most popular fields of application for organic semiconductors is organic LEDs. The most popular are phosphorescent organic light-emitting diodes, where the theoretical internal quantum efficiency can reach up to 100 %, but so far, the technology has not reached this number. In order to improve efficiency, new, efficient materials have to be synthesized and used in the production of organic LEDs. In this study, new diaryl derivatives containing a fluorene moiety were synthesized and characterized, these diaryl derivatives were used as hole transport materials in organic LEDs. The chemical structures of the compounds were approved by applying mass spectroscopy and nuclear magnetic resonance methods. The destruction temperature determined by thermogravimetric analysis ranged from 276 to 361 °C. After carrying out a differential scanning calorimetry experiment, the glass transition temperatures ranged from 31 to 74 °C. The obtained results indicate that the glass transition temperature values are low, but the quality of the amorphous layers is suitable for optical experiments. The device that has the best characteristics achieved a maximum current efficiency of 2.8 cd/A, a luminance of 7760 cd/m2, and the switching voltage of the device was 4.6 V. Recently, there has been a lot of interest in third-generation organic light-emitting diodes, which are characterized by thermally activated delayed fluorescence (TADF). In these devices, heavy metal complexes are replaced by organic compounds. During this work, a new generation of electroactive compounds containing a 1,8-naphthalimide moiety was synthesized and characterized, and these compounds were used in the emission layers of organic light-emitting diodes as emitters. The chemical structures of the derivatives were approved by applying mass spectroscopy and nuclear magnetic resonance methods. The glass transition temperatures determined by differential scanning calorimetry ranged from 133 to 160 °C, indicating that the compounds are suitable for organic LEDs. Of all the created devices, the best prototype was the one with a commercial host of di (N-carbazolyl) biphenyl (CBP) in the emissive layer and 7.5% of N-(9-ethylcarbazol-3-yl)-4-{3-[4-(carbazol-9-yl)phenyl]carbazol-9-yl}-1,8-naphthalimide. The device has demonstrated a maximum luminance of 2377 cd/m2, achieved 10 cd/A current efficeincy, 9 lm/W power efficiency and 2.39 % maximum external quantum efficiency. During the work, a recommended technological scheme for the synthesis of compounds containing a 1,8-naphthalimide moiety was created and the hazards of the materials used were assessed. |
