Carbazole and benzimidazole/oxadiazole hybrids as bipolar host materials for sky blue, green, and red PhOLEDs

Anomalously Long-Lasting Blue PhOLED Featuring Phenyl-Pyrimidine Cyclometalated Iridium Emitter

“…Phosphorescent Ir complexes with dfppm as the cyclometalating ligand, including MS 2, had been reported previously. [29][30][31] Unfortunately, with rather preliminary characterizations and inferior EL efficiencies in previous reports, the potential of such Ir complexes was substantially underestimated, and they failed to arouse sufficient attention and interest. Our studies elaborated here revitalize this class of Ir complexes as excellent phosphorescent emitters in OLEDs.…”

“…However, as a benchmark blue phosphor for high-performance phosphorescent OLEDs (PhOLEDs), FIrpic has certain shortcomings that are common to many reported blue phosphorescent emitters. These include unsatisfactory CIE color coordinates for full-color displays, significant efficiency roll-off at higher brightness, and short device operating lifetimes, [29][30][31][32][33] the improvement of which remains essential and critical for OLED applications. In this work, we explore the potential of replacing difluorophenyl-pyridine (dfppy), which is commonly used as the cyclometalating ligand for blue-emitting Ir complexes (e.g., FIrpic), with the diazine-containing ligand, difluorophenyl-pyrimidine (dfppm), affording compound MS 2 (Scheme 1).…”

P‐185: Highly Efficient and Long Lifetime Bipolar Host Material for Red Phosphorescent Organic Light‐Emitting Diodes Using Benzocarbazole and Diphenyltriazine Derivatives

“…Recently, many bipolar hosts have been developed to improve the device efficiency and lifetime of red phOLEDs. Developed bipolar host is composed of a number of electron acceptors (quinazoline, quinoxaline, triazine, oxadiazole, and imidazole) [2][3][4][5] and electron donor (carbazole, diazacarbazole, diphenylacridine and phenothiazine) [6][7][8][9] and proved that a number of bipolar hosts can show higher than 20% EQE in red phOLEDs but still many bipolar hosts with high efficiency and long lifetime have not yet been reported. [10][11][12] Herein, two bipolar hosts, 7-(4-(4,6-diphenyl-1,3,5-triazin-2yl)phenyl)-7H-benzo[c]carbazole (BCTrz1) and 7-(3-(4,6diphenyl-1,3,5-triazin-2-yl)phenyl)-7H-benzo[c]carbazole (BCTrz2), are introduced as red hosts for Ir(mphmq) 2 (tmd) [Iridium(III)bis(4-methyl-2-(3,5-dimethylphenyl)quinolinato-N ,C2′) tetramethylheptadionate] phosphorescent emitter.…”

Synthesis, structure, photophysical and electroluminescent properties of a blue-green self-host phosphorescent iridium(III) complex

“…The mixture was stirred at room temperature for 24 h and then washed with deionized water and dried. The precipitate was purified by column chromatography (silica gel, dichloromethane: petroleum ether ¼ 1: 20) to obtain a white crystal product (yield: 56%); m. p. 3.36 (t, J ¼ 6.6 Hz, 2H, CH 2 ), 1.82e1.90 (m, 4H, CH 2 ), 1.41e1.48 (m, 4H, CH 2 ). 13 …”

“…However, the serious problem of concentration quenching at high current density limits its application. The iridium(III) complexes have to be utilized as guest in phosphorescent organic light emitting devices (PhOLEDs) [3]. Therefore, appropriate match of energy levels between host and guest is necessary [4e7] in order to obtain efficient energy transfer and restrain energy transfer back from guest to host which would reduce the electroluminescent performance.…”