SYNTHESIS AND CHARACTERIZATION OF DIBENZOTHIOPHENE DERIVATIVES AS THERMALLY ACTIVATED DELAYED FLUORESCENCE EMITTERS

Thermally activated delayed fluorescence materials have emerged as the most promising candidates for constructing high-performance organic light-emitting-diodes (OLEDs) due to their efficient harvest of both singlet and triplet excitons through the reverse intersystem crossing (RISC) process [1,2]. In this work organic semiconductors with differently substituted donor-acceptor molecular structure were synthesized and investigated by different experimental methods. The molecular structures were certified through ¹H and ¹³C NMR spectroscopies, mass spectrometry. The following characterizations of new compounds were mainly performed 1) photophysical measurements, 2) evaluation of thermal properties, 3) energy level measurements, 4) charge transport characterization. Upon such examinations it was concluded that, their neat films emit cyan/green fluorescence with PLQY of 7.7% in the best case. Their 5% weight loss temperature exceeded of 300 °C. Ionization potentials of the studied compounds were in the range of 5.5-5.62 eV. The studied compounds were characterized by hole-transporting properties reaching 10^-3 cm²/Vs at high electric fields in the best cases. According provided characterizations, selected compounds may be used as hole-transporting materials in OLEDs.