I. Hladka “Synthesis and studies of new organic electroactive compounds containing donor and acceptor moieties” doctoral dissertation defense

Author, Institution: Iryna Hladka, Kaunas University of Technology

Science area, field of science: Technological Sciences, Materials Engineering T 008

Scientific Supervisor: Prof. Habil. Dr. Juozas Vidas Gražulevičius (Kaunas University of Technology,
Technological sciences, Materials Engineering T 008)

Scientific Advisor: Dr. Dmytro Volyniuk (Kaunas University of Technology, Natural Sciences,
Chemistry, N 003)

Dissertation Defence Board of Material Engineering Scientific Field:

Prof. Dr. Habil. Sigitas Tamulevičius (Kaunas University of Technology, Technological sciences, Materials Engineering, T 008) – chairman;
Dr. Mindaugas Andrulevičius (Kaunas University of Technology, Technological sciences, Materials Engineering, T 008);
Prof. Dr. Saulius Grigalevičius (Kaunas University of Technology, Technological sciences, Materials Engineering, T 008);
Prof. Habil. Dr. Vidmantas Gulbinas (Centre for Physical Sciences and Technology, Natural Sciences, Physics, N 002);
Prof. Dolores Velasco (University of Barcelona, Natural Sciences, Chemistry, N 003).

The doctoral dissertation is available on the internet and and at the library of Kaunas University of Technology (K. Donelaičio St. 20, Kaunas, Lithuania).

Annotation:

In this work, synthesis and properties of new organic materials, containing donor and acceptor moieties, are presented. The W-shaped derivatives of carbazole and oxadiazole with the differently substituted phenyl ring are characterized by  high energy of triplet levels (up to 3.04 eV), blue emission in solid state, two materials were characterized by bipolar charge-transporting properties reaching 1 × 10⁻⁴ cm²/V and were used as a hosts in blue phosphorescent OLEDs. The devices demonstrated pure emission of the phosphorescent emitter and reached an 8.8% value of external quantum efficiency and a brightness of 8700 cd/m² at the applied voltage of 10 V. Acridan and perfluorobiphenyl derivatives are characterized by the combination of thermally activated delayed fluorescence and aggregation induced emission enhancement. Two crystalline polymorphs were obtained for one compound, and their properties and crystal structures were investigated. The derivatives were used as emitters in blue/sky-blue OLEDs. The best fabricated device demonstrated low value of turn-on voltages of 3.0 V and high external quantum efficiency of 16.3%. The investigated organoboron complexes demonstrated high photoluminescence quantum yields of the solutions in non-polar solvents and positive solvatochromism and short fluorescence lifetimes.