Design, Synthesis and Photophysical Properties of Novel Tetrahedral Carbazole-Bridged Silanes with Benzimidazole Groups

2012 ◽  
Vol 268-270 ◽  
pp. 23-27
Author(s):  
Qing Yu Ma ◽  
Rui Fang Guan ◽  
Guo Zhong Li ◽  
Deng Xu Wang
Keyword(s):  
Photophysical Properties ◽  
Band Gaps ◽  
Organic Light Emitting Diodes ◽  
Design Synthesis ◽  
Light Emitting ◽  
Organic Light ◽  
Host Materials ◽  
Blue Emitters ◽  
Molecular Calculations ◽  
Homo Lumo

Two novel luminescent molecules based on tetrahedral silicon core with the carbazole and benzimidazole groups, bis(6-(1H-benzo[d]imidazol-1-yl)-9-ethyl-9H-carbazol-3-yl)dimethylsilane (1) and bis(6-(1H-benzo[d]imidazol-1-yl)-9-ethyl-9H-carbazol-3-yl)diphenylsilane (2), were designed, synthesized and fully characterized by IR, 1H NMR, 13C NMR and elemental analysis. Thermal results show that these compounds have high thermal stability and glass-transition temperature (Tg). The results based on the photophysical properties and molecular calculations reveal that they are fluorescent with emission in the region of violet to blue and own large HOMO-LUMO band gaps, making them potentials as blue emitters, host materials or charge blocking materials in organic light-emitting diodes (OLEDs) display.

The study on two kinds of spiro systems for improving the performance of host materials in blue phosphorescent organic light-emitting diodes

2015 ◽  
Vol 3 (35) ◽  
pp. 9053-9056 ◽  
Author(s):  
Xiang-Yang Liu ◽  
Feng Liang ◽  
Lei Ding ◽  
Shou-Cheng Dong ◽  
Qian Li ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Light Emitting Diodes ◽  
Photophysical Properties ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Host Materials ◽  
Blue Phosphorescent

The introduction of spiro-acridine-fluorene (SAF) can affect the electronic structure of the whole molecule, which made SAF-based materials exhibit totally different photophysical properties from conventional spirobifluorene-based materials.

Design principles of carbazole/dibenzothiophene derivatives as host material in modern efficient organic light-emitting diodes

2017 ◽  
Vol 5 (28) ◽  
pp. 6989-6996 ◽  
Author(s):  
Junming Li ◽  
Shou-Cheng Dong ◽  
Andreas Opitz ◽  
Liang-Sheng Liao ◽  
Norbert Koch
Keyword(s):  
Carrier Transport ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Photophysical Properties ◽  
Energy Levels ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Host Materials

Host materials for modern high-efficiency organic light-emitting diodes (OLEDs) based on phosphorescence and thermally activated delayed fluorescence were optimized with respect to thermal stability, photophysical properties, energy levels, and charge carrier transport.

Fluorinated Poly(N-vinylcarbazole) Host for Triplet Energy Confinement on Phosphorescent Emitter in Organic Light-emitting Diodes

2009 ◽  
Vol 1197 ◽  
Author(s):  
Yukitami Mizuno ◽  
Isao Takasu ◽  
Shuichi Uchikoga ◽  
Shintaro Enomoto ◽  
Tomoaki Sawabe ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Energy Gap ◽  
Organic Light Emitting Diodes ◽  
Lumo Energy ◽  
Light Emitting ◽  
Energy Gaps ◽  
Organic Light ◽  
Host Materials ◽  
Homo Lumo ◽  
Polymer Host

AbstractFluorinated carbazoles as host materials have been investigated for highly efficient organic light emitting diodes (OLEDs). By molecular orbital calculations, we found that fluorinations at position 2, 4, 5 and 7 of carbazole ring were effective for widening HOMO-LUMO energy gap. The energy gaps of our synthesized 2,7-difluorocarbazole (F2-Cz) and 2,4,5,7-tetrafluorocarbazole (F4-Cz), were estimated to be 3.71 eV and 3.87 eV by the absorption spectra, respectively. These energy gaps were higher than that of the non-substituted carbazole (Cz, 3.59 eV). We synthesized poly(N-vinyl-2,7-difluorocarbazole) (F2-PVK) and poly(N-vinyl-2,4,5,7-tetrafluorocarbazole) (F4-PVK) as solution processable polymer host materials. However, the F4-PVK was found to be an unsolved polymer. The F2-PVK could be compared with non substituted poly(N-vinylcarbazole) (PVK) in OLEDs. The emission layer (EML) contained iridium(III) bis [(4,6-di-fluorophenyl)-pyridinato-N,C2′] picolinate (FIrpic) as a blue phosphorescent dopant, and iridium(III) bis [2-(9,9-dihexylfluorenyl)-1-pyridine] acetylacetonate as a yellow dopant. The white OLED with the F2-PVK showed 1.4 times higher luminous current efficiency (24 cd/A) than the PVK (17 cd/A). These data show that the excitation energy is confined on dopants by using fluorinated polymer host material with higher T1 corresponding to wider HOMO-LUMO energy gap.

Novel Carbazole-based Multifunctional Materials with Hybridized Local and Charge-Transfer Excited State Acting as Deep Blue Emitters and Phosphorescent Hosts for Highly Efficient Organic Light-Emitting Diodes

2021 ◽  
Author(s):  
Haitao Zhou ◽  
Mengna Yin ◽  
Zhenhong Zhao ◽  
Yanqin Miao ◽  
Xin Jin ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Multifunctional Materials ◽  
Light Emitting ◽  
Highly Efficient ◽  
Deep Blue ◽  
Organic Light ◽  
Blue Emitters

In this work, two carbazole- and benzo[d]oxazole-based novel multifunctional materials with hybridized local and charge-transfer (HLCT) characteristic, namely OCI and OCT, which could act as deep-blue fluorophors and phosphorescent hosts,...

Four color stacked white organic light-emitting diodes utilizing the concept of triplet harvesting

2011 ◽  
Vol 1286 ◽  
Author(s):  
Th. C. Rosenow ◽  
S. Olthof ◽  
S. Reineke ◽  
B. Lüssem ◽  
K. Leo
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Organic Light Emitting Diodes ◽  
Light Sources ◽  
Emission Layer ◽  
Light Emitting ◽  
Organic Light ◽  
Blue Emitters ◽  
Color Rendering ◽  
Triplet Harvesting

ABSTRACTOrganic light-emitting diodes (OLEDs) are developing into a competitive alternative to conventional light sources. Nevertheless, OLEDs need further improvement in terms of efficiency and color rendering for lighting applications. Fluorescent blue emitters allow deep blue emission and high stability, while phosphorescent blue emitter still suffer from insufficient stability. The concept of triplet harvesting is the key for achieving internal quantum efficiencies up to 100 % and simultaneously benefiting from the advantages of fluorescent blue emitters. Here, we present a stacked OLED consisting of two units comprising four different emitters in total. The first unit takes advantage of the concept of triplet harvesting and combines the light emission of a fluorescent blue and a phosphorescent red emitter. The second unit emits light from a single emission layer consisting of a matrix doped with phosphorescent green and yellow emitters. With this approach, we reach white color coordinates close to the standard illuminant A and a color rendering index of above 75. The presented devices are characterized by high luminous efficacies of above 30 lm/W on standard glass substrates without outcoupling enhancement.

High-efficiency red, green and blue phosphorescent homojunction organic light-emitting diodes based on bipolar host materials

2011 ◽  
Vol 12 (5) ◽  
pp. 843-850 ◽  
Author(s):  
Chao Cai ◽  
Shi-Jian Su ◽  
Takayuki Chiba ◽  
Hisahiro Sasabe ◽  
Yong-Jin Pu ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Host Materials ◽  
Blue Phosphorescent
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