Highly Efficient Bipolar Host Materials with Indenocarbazole and Pyrimidine Moieties for Phosphorescent Green Light-Emitting Diodes

Abstract

In this paper, we report bipolar host materials, 6- (2,6-diphenylpyrimidin-4-yl)-12,12-dimethyl-6,12,12′-trihydroindeno[1,2-b]carbazole (DPICz1) and 6-(2,6-diphenyl-pyrimidin-4-yl)-12,12-dimethyl-6,12,12′trihydroindeno[1,2-b]carbazole (DPICz2), with indenocarbazole moiety as a hole-transporting unit and pyrimidine moiety as an electron-transporting unit for highly efficient green phosphorescent organic light-emitting diodes. The synthesized materials show excellent electro-optical properties. Similarly, it also exhibits outstanding thermal and morphological stability due to high glass transition temperature (T g ) of 161 °C and decomposition temperature (T d ) of 327−401 °C. Fabricated green phosphorescent organic light-emitting diode shows excellent current and power efficiency of 77.8 cd/A and 62.8 lm/W as well as almost ideal external quantum efficiency of 22.3% at the brightness of 1000 cd/m 2 .

High thermal-stability benzocarbazole derivatives as bipolar host materials for phosphorescent organic light-emitting diodes

“…Here, two key intermediate compounds 9-(dibenzo [b,d]thiophen-4-yl)-7H-benzo[c] carbazole (1e3) and 5-(dibenzo[b,d]thiophen-4-yl)-7H-benzo[c]carbazole (2e4) were prepared through multiple steps according to the methods reported in the litertures [22,23]. Subsequently, the desired products (DYNS and DYSN) were obtained by the palladium catalyzed BuchwaldeHartwig cross coupling reaction of benzocarbazole species (1e3 and 2e4) and bromide intermediate 2-(4-bromophenyl)-1-phenyl-1H-benzo[d]imidazole in 60% yield.…”

New bipolar host materials for high performance of phosphorescent green organic light-emitting diodes

“…27 Herein phenyl group is inserted between indenocarbazole and biphenyl pyrimidine moieties, which are connected to their para-and meta-position by Suzuki-coupling, respectively (See Scheme 1). 27 Herein phenyl group is inserted between indenocarbazole and biphenyl pyrimidine moieties, which are connected to their para-and meta-position by Suzuki-coupling, respectively (See Scheme 1).…”

“…D. Ma et al developed a bipolar host materials with triphenylamine and oxadiazole as hole and electron transporting moieties, which exhibits a maximum EQE of 22.7% and good charge transport characteristics for phosphorescent green device. 27 Based on these results we have developed series of host materials using indenocarbazole moiety to further enhance the OLED performances in terms of efficiency and lifetime. 16 Likewise, phenanthroimidazole and carbazole were utilized as the electron and hole transporting units for bipolar host materials, which, displayed a very high glass transition temperature (T g ) of 113-243 C and decomposition temperature (T d ) of 395-417 C. They also showed a maximum EQE of 21.0%.…”

Photoluminescence and Electrochemiluminescence of Thermally Activated Delayed Fluorescence (TADF) Emitters Containing Diphenylphosphine Chalcogenide-Substituted Carbazole Donors

“…The majority of examples revolve around substituted carbazole derivatives and can be broadly categorized into two families: (i) substituents that enhance the electron-donating strength of carbazole and promote a red-shift in the emission, and; (ii) substituents that reduce the electron-donating strength of the carbazole and promote a blue-shift in the emission. 36 Electron-rich carbazole derivatives used within TADF emitter design include 3,6-dimethylcarbazole, 37 3,6-dimethoxycarbazole, 38 3,6-di-t-butylcarbazole, [37][38] fluorene-fused carbazole, 39 benzofuran-fused carbazole, 40 donor-dendronized carbazole [41][42] benzothiophene-fused carbazole, 43 and paracyclophane-fused carbazole. 44 In contrast, 3,6diphenylcarbazole, 10 9-phenylcarbazole, 45 α-/β-/δ-carboline, [46][47][48][49][50] indolocarbazole, 51 diphenylphosphine oxide-substituted carbazole derivatives, 52 triaryl and diarylboronatesubstituted carbazole derivatives, 53 and cyanocarbazoles [54][55] represent examples of electronpoor carbazole derivatives reported in the TADF literature.…”