Abstract
Two novel bipolar host materials, 2-(9-phenyl-9H-carbazol-3-yl)quinazolin-4(3H)-one (3CBZ-QZ) and 2-(4-(9H-carbazol-9-yl)phenyl)quinazolin-4(3H)-one (9-CBZQZ), have been designed, synthesized, characterized, and used as host materials for PhOLEDs in this work with the goal to provide balanced charge flux for enhanced PhOLED device efficiency. The design of these compounds incorporates 2-aminobenzamide as an electron acceptor with electron-transporting capabilities and carbazole as an electron donor with hole-transporting properties. Furthermore, the absorption, emission, electrochemical, thermal and theoretical characteristics of these synthesized materials are also reported. The synthesized compounds exhibited relatively high thermal stability with 5% weight loss at temperatures exceeding 380oC. The position of the quinoxaline ring in relation to the phenyl ring of N-phenyl carbazole has been determined to have a substantial impact on the characteristics of the molecules. The conjugation and physical characteristics of these molecules were seen to differ when the linkage location of the donor-acceptor system was changed. A slight change in absorption is observed due to the substitution on carbazole. The emission properties for both molecules are also determined by performing TD-DFT calculations on optimized structures in first excited state (S1). For these compounds, the band gap between the LUMO and HOMO was found to be 3.18 eV and 3.21 eV for 3-CBZ QZ and 9-CBZ QZ respectively. Both molecules are useful for better hole and electron transporting agents for charge transporting materials. They become likely structures for creating very effective electro-phosphorescence devices because of the appropriate HOMO-LUMO gap.
