Polymers with Carbazole-Oxadiazole Side Chains as Ambipolar Hosts for Phosphorescent Light-Emitting Diodes

Abstract

Polymethacrylates, polystyrenes, and polynorbornenes bearing 2-(3-(carbazol-9-yl)phenyl)-5-phenyl-1,3,4-oxadiazole, 2-(4-(carbazol-9-yl)phenyl)-5-phenyl-1,3,4-oxadiazole, 2-(3,5-di(carbazol-9-yl)phenyl)-5-phenyl-1,3,4-oxadiazole) groups linked to the polymer backbone through the 3-position of their terminal phenyl groups have been synthesized for use as solution-processable ambipolar hosts for phosphorescent light-emitting diodes. The polymers exhibit good thermal stabilities, with no weight loss below 350 °C, and have glass-transition temperatures in the range 118–209 °C. Spectroscopic, electrochemical, and quantum-chemical data for small-molecule model compounds suggest that the side chain groups are suitable hosts for a range of phosphors, including the green-emitter fac-tris(2-phenylpyridinato-N,C 2′)iridium (Ir(ppy)3). Light-emitting diodes were fabricated, each with a solution-processed photo-cross-linked hole-transport layer, a solution-processed emissive layer composed of a carbazole-oxadiazole-functionalized polymethacrylate doped with Ir(ppy)3, and an evaporated electron-transport layer. The polymer with 2-(3,5-(dicarbazol-9-yl)phenyl)-5-phenyl-1,3,4-oxadiazole units in the side chain exhibited the lowest turn-on voltage (6.0 V), and the highest efficiency (external quantum efficiency of 10.0%, current efficiency of 34.1 cd/A).

Solution-Processed Blue/Deep Blue and White Phosphorescent Organic Light-Emitting Diodes (PhOLEDs) Hosted by a Polysiloxane Derivative with Pendant mCP (1,3-bis(9-carbazolyl)benzene)

“…[53][54][55][56][57] This confirms that the polysiloxane backbone has only minimal influence on the photophysical properties of the pendant mCP chromophore. The triplet energy (E T ) of PmCPSi was obtained from its phosphorescence spectrum at 77 K in dichloromethane: a well-structured band is observed in the 400-550 nm region.…”

Crystal structure of 5-(adamantan-1-yl)-3-[(2-trifluoromethylanilino)methyl]-2,3-dihydro-1,3,4-oxadiazole-2-thione, C20H22F3N3OS

“…In addition, numerous adamantane derivatives were reported to exhibit marked anticancer [9,10], antibacterial [11][12][13][14] and antifungal [15] activities. 1,3,4-Oxadiazole derivatives were early recognized as a structural motif of particular value in medicinal chemistry [16][17][18], material sciences [19] and agrochemistry [20]. In the present study, we report the structural properties of the title 1,3,4-oxadiazole-N-Mannich base which was reported to exhibit potent antibacterial and marginal antifungal and anti-HIV-1 activity [8].…”

Crystal structure of 2-[3,5-bis(trifluoromethyl)benzylsulfanyl]-5-(5-bromothiophen-2-yl)-1,3,4-oxadiazole, C15H7BrF6N2OS2

“…In addition, some 1,3,4-oxadiazoles are currently used as safe herbicides for crop protection [19][20][21]. Moreover, 1,3,4-oxadiazole derivatives are widely employed electrontransporting and hole-blocking materials in the development of organic light-emitting diodes (OLEDs) [22]. The asymmetric unit cell of the title compound contains one independent molecule.…”