S. Nasiri “Investigation of the properties of new organic electroactive compounds exhibiting either prompt or delayed fluorescence” doctoral dissertation defence

Author, Institution: Sohrab Nasiri, Kaunas University of Technology

Science area, field of science: Technological Sciences, Materials Engineering, T008

Scientific Supervisor: Prof. Habil. Dr. Juozas Vidas Gražulevičius (Kaunas University of Technology, Technological sciences, Materials Engineering T008)

Scientific Advisor: Dr. Dmytro Volyniuk (Kaunas University of Technology, Natural Sciences, Chemistry, N003)

 Dissertation Defence Board of Materials Engineering Scientific Field:
Prof. Dr. Saulius Grigalevičius (Kaunas University of Technology, Technological sciences, Materials Engineering, T008) – chairman
Prof. Dr. Arvaidas Galdikas (Kaunas University of Technology, Technological sciences, Materials Engineering, T008)
Prof. Dr. Alexander Kukhta (Belorussian State University, Belarus, Natural sciences, Physics, N002)
Dr. Šarūnas Meškinis (Kaunas University of Technology, Technological sciences, Materials Engineering, T008)
Prof. Dr. Rasa Pauliukaitė (Centre for Physical Sciences and Technology, Natural Sciences, Physics, N002)

The doctoral dissertation is available at the library of Kaunas University of Technology (K. Donelaičio g. 20, Kaunas).

Annotation:

Organic light-emitting diodes (OLEDs) emerged as one of the most dominant display technologies and potentially as the next generation solid-state light source. Generally, OLEDs are double charge injection devices, requiring simultaneous injection of both electrons and holes into the adjacent organic layer, which is followed by the emission of the electroluminescence. A facile, balanced charge transport and high conversion efficiency of excitons to light are required for an efficient OLED. To achieve efficient recombination of holes and electrons in the emitting layer, π-conjugated structure of organic electroluminescent materials is required. Also, suitable optical and photophysical properties, good thermal and morphological stability, as well as appropriate energy levels are the main requirements for organic electroactive materials intended for the fabrication of highly efficient electroluminescent devices. A combination of different donor (D) and acceptor (A) moieties in the structures of organic electroactive compounds makes possibility to achieve a big range of desired properties. The aim of this work is investigation and comprehensive analysis of the properties and of performance in OLEDs of new organic electroactive compounds necessary for the establishment of structure-properties relationship.

To achieve the aim of the work, the following tasks are formulated:

• Investigation of photophysical and electroluminescent properties of carbazole derivatives containing one or two tetra-/triphenylethenyl units.
• Evaluation of photophysical, photoelectrical and charge transporting properties of xanthenone derivatives.
• Investigation of photophysical, electrochemical and electroluminescent properties of the derivatives tetrahydrodibenzophenanthridine and phenanthroimidazole.
• Investigation of photophysical properties, fabrication and characterization of OLEDs based on tetra‐/triphenylethenyl substituted 9,9‐dimethylacridine derivatives.
• Investigation of electroluminescent properties of non-doped and doped devices based on unsymmetrical D-A-D’ type TADF emitters in which differently substituted carbazole donor moieties are directly linked to the quinoxaline unit.