Synthesis and photophysical studies of red phosphorescent Ir(III) complexes chelated with a thienopyridyl ligand for white organic light-emitting diodes

• Published in: Molecular Crystals and Liquid Crystals Vol. 659; no. 1; pp. 121 - 126
• Main Authors: Cho, So Hyeon, Lee, Seul Bee, Ha, Yunkyoung
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis Ltd 12.12.2017
• Subjects: Coordination compounds; Doppler effect; Iridium; Iridium compounds; Ligands; Luminescence; NMR; Nuclear magnetic resonance; Optical properties; Organic light emitting diodes; Phosphorescence; Photoluminescence; Red shift; Spectra
• ISSN: 1542-1406; 1563-5287; 1527-1943
• DOI: 10.1080/15421406.2018.1450951

For efficient white organic light-emitting diodes (OLEDs), it is necessary for luminescence to cover a wide range of visible light area. According to these needs, we synthesized new types of red phosphorescent iridium(III) complexes and compared their luminescent properties with the previously reported iridium complexes. The iridium complexes that we investigated and compared herein have 2-phenylquinoline (pq) as main ligands and 4-(1-Naphtyl)thieno[3,2-c]pyridine (1-NTP), 4-(2-Naphthyl)thieno[3,2-c]pyridine (2-NTP) and 4-(p-biphenyl)thieno[3,2-c]pyridine (BTP) as ancillary ligand, respectively. We characterized the complexes with 1H NMR and mass spectrometer. The photoluminescence (PL) spectra of the resulting iridium complexes, (1-NTP)Ir(pq)2, (2-NTP)Ir(pq)2 and (BTP)Ir(pq)2 exhibited red shift about 15 to 20 nm compared to a well-known red complex, (acac)Ir(pq)2. The bathochromic shift in luminescence seems to be caused by a thienopyridyl derivative in the ancillary ligands. Furthermore, the PL spectra of the complexes prepared in this study exhibited wide range phosphorescence with the full-width at half maximum (FWHM) of ∼100 nm. We also measured their bandgaps with cyclic voltammetry (CV) and studied their relationships with the corresponding UV-Vis spectra.