Bipolar carbazole/quinoxaline-based host materials for efficient red PhOLEDs

Rational design of quinoxaline-based bipolar host materials for highly efficient red phosphorescent organic light-emitting diodes

“…2a, the absorption of M1 and M2 exhibits bands in the range from 250 to 430 nm (247, 298, 387 nm for M1; 254, 303, 378 nm for M2), attributed to the p-p* electronic transition of the quinoxaline and carbazole unit. 33,34,[40][41][42] M1 and M2 show almost the same absorption spectra in spite of the larger p-electron conjugation of compound M2, implying that the introduction of the phenyl spacer almost has little effect on the absorption properties of these donor-acceptor systems.…”

“…S4, † indicating that the connection ways of electron acceptor/donor moieties have great inuence on performance of the host materials (Table 2). 34…”

“…[21][22][23][24][25][26][27][28][29][30][31][32] The red emission component is an integral part of both highquality solid state lightings and displays. [33][34][35][36][37][38][39] The performance of red phosphorescent OLEDs is not determined by phosphors themselves, but also closely related to the host materials. Bipolar host materials that could balance the carriertransportations for improving the efficiency of phosphorescent OLEDs have become the current research focus.…”

“…[40][41][42] Recently, diphenylquinoxaline derivatives showing excellent electron-transportation property also have been selected as the novel acceptor moiety to realize the bipolar host materials. 33,34 For instance, Cheng et al designed an excellent bipolar host material which is composed of two 6Hindolo [2,3-b]quinoxaline unit bridged by the tetraphenylsilane core realizing high-efficiency red phosphorescent OLEDs. 33 It is still necessary to further explore the quinoxaline-based bipolar host materials.…”

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.…”