High efficient organic light emitting diodes using new 9,10-diphenylanthracene derivatives containing bulky substituents on 2,6-positon (original) (raw)
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A series of new asymmetric anthracene derivatives have been successfully synthesized for use in the light emitting layer of solution processed blue fluorescent organic light emitting diodes (OLEDs), which could be used both as host and dopant. Especially, new synthetic blue fluorescent materials with anthracene moieties without any alkyl chains showed high solubility in common organic solvents probably due to their severely twisted internal structures. They also show moderately high thermal stability due to their rigid internal core units. With those novel soluble blue fluorescent materials, we created moderately efficient solution-processed fluorescent OLEDs. And a new anthracene derivative [9-(9,10-di(naphthalen-2-yl)anthracen-2-yl)-9H-carbazole (DN-2-CzA)] as a host material exhibited moderately high efficiency and external quantum efficiency of up to 3.2 cd/A and 1.6%, respectively, when we utilized 4,4 0-bis[4-(diphenylamino)styryl]biphenyl as a dopant. Meanwhile, the [N-(naphthalen-1-yl)-9,10-di(naphthalen-2-yl)-N-phenylanthra-cen-2-amine (DN-2-NPAA)] as a dopant material showed pretty good device performance, up to 5.2 cd/A and 2.2% (EQE), when we utilized 2-tert-butyl-9,10-di(naphth-2-yl) anthracene as a host.
Deep blue organic light-emitting diodes of 1,8-diaryl anthracene
Journal of Chemical Sciences
We report on the optimization of organic light emitting diode (OLED) devices using 1,8-di-(4trifluromethylphenyl)-anthracene (CF3-DPA) as the active emissive layer. CF3-DPA emits in the deep blue region with an emission peak at 432 nm in solution which showed a slight red shift in thin films. CF3-DPA has high reported fluorescence quantum efficiency, ∼67%, as compared to 9,10-diphenyl anthracene (9,10-DPA). We optimized the OLED devices with different hole transporting layers (HTLs). Bilayer devices formed with N ,N-di(1-naphthyl)-N ,N-diphenyl-(1,1-biphenyl)-4,4-diamine (NPD) as the HTL gave a reasonable light output. We observed that trilayer or multilayer devices with the inclusion of poly(3,4-ethylene dioxythiophene)poly(styrene sulfonate) (PEDOT:PSS) and/or copper phthalocyanine as an additional HTL reduced the turn on voltage by ∼5 to 9 V, though the brightness of the light emission also decreased. Including suitable carrier (electron or hole) transporting layers like 2, 2 ,2-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) and 4,4-Bis(N-carbazolyl)-1,1-biphenyl (CBP) increases the efficiency of the devices. From our studies, we conclude that though NPD/CF3-DPA interface is crucial for light emission, the performance of the devices is limited by the mismatch of the hole and electron mobilities and the low internal quantum efficiency of CF3-DPA in the solid state. Devices having ITO/NPD/CF3-DPA/TPBi/LiF-Al geometry were observed to be the most efficient.
The Journal of Physical Chemistry A, 2006
Molecular level parameters are investigated computationally to understand the factors that are responsible for the higher efficiency in derivatives of 9,10-bis(1-naphthyl)anthracene (R-ADN), 9,10-bis(2-naphthyl)anthracene (-ADN), their tetramethyl derivatives (R,-TMADN) and the t-Bu derivative (-TBADN) as blue light emitting electroluminescent (EL) layers in organic light emitting diodes (OLEDs). DFT studies at the B3LYP/6-31G-(d,p) level have been carried out on the substituted anthracenes. The absorption spectra are simulated using time dependent DFT methods (TD-DFT) whereas the emission spectra are approximated by optimizing the excited state by HF/CI-Singles and then carrying out the vertical CI calculations by the TD-DFT method. The reorganization energy for estimating the hole and electron transport is calculated. The transfer integrals between parallely stacked molecules in the bulk state are estimated by calculating the electronic splitting. The substituted anthracenes are compared with unsubstituted anthracene and yet untested 9,10-dianthrylanthracene (TANTH). A larger and slower buildup of the electrons and holes in the EL layer, due to the higher reorganization energy and smaller electronic coupling between the adjacent molecules could lead to an increase in hole-electron recombination in the layer and thus increase the efficiency.
Journal of Materials Chemistry C, 2014
PAPER Chin-Ti Chen, Chao-Tsen Chen, Chi-Jung Su et al. High effi ciency non-dopant blue organic light-emitting diodes based on anthracene-based fl uorophores with molecular design of charge transport and red-shifted emission proof Volume A new series of 9,10-diphenylanthracene (DPA)-based blue fluorophores have been synthesized and characterized for organic light-emitting diode (OLED) applications. These fluorophores have a bulky substituent, such as triphenylsilane in TPSDPA and mesitylene in TMPDPA, on the C-2 position. The C-2 substituent also includes electron transporting diphenylphosphine oxide in PPODPA and dimesitylene borane in BMTDPA, or hole transporting N-phenylnaphthalen-1-amine in NPADPA. For TMPDPA blue fluorophores, 9,10-diphenyl substituents of the anthracene core are further attached to holetransporting 9H-carbazole in CBZDPA and electron-transporting 2-phenyl-1,3,4-oxadiazole in OXDDPA. Absorption and emission spectroscopic properties of all DPA-derived fluorophores, either in solution or in the condensed phase, were fully characterized and the HOMO/LUMO energy levels of these fluorophores were determined. The frontier molecular orbitals of the DPA derivatives were analysed by theoretical methods to determine the possible intramolecular charge transfer (ICT) characteristics.
Organic Electronics, 2012
A series of new blue materials based on highly fluorescent di(aryl)anthracene and electrontransporting phenanthroimidazole functional cores: 2-(4-(anthracen-9-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (ACPI), 2-(4-(10-(naphthalen-1-yl)anthracen-9yl)phenyl)-1-p-henyl-1H-phenanthro[9,10-d]imidazole (1-NaCPI), 2-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (2-NaCPI) were designed and synthesized. These materials exhibit good film-forming and thermal properties as well as strong blue emission in the solid state. To explore the electroluminescence properties of these materials, three layer, two layer and single layer organic light-emitting devices were fabricated. With respect to the three layer device 4 using ACPI as the emitting layer, its maximum current efficiency reaches 4.36 cd A À1 with Commission Internationale del'Eclairage (CIE) coordinates of (0.156, 0.155). In the single layer device 10 based on ACPI, maximum current efficiency reaches 1.59 cd A À1 with Commission Internationale del'Eclairage (CIE) coordinates of (0.169, 0.177). Interestingly, both device 4 and 10 has low turn on voltage and negligible efficiency roll off at high current densities.
Journal of Materials Chemistry, 2009
We have synthesized and characterized a novel blue-emitting material, 2-tert-butyl-9,10-bis[4 0-(9-ptolyl-fluoren-9-yl)biphenyl-4-yl]anthracene (BFAn), containing an anthracene core end-capped with 9-phenyl-9-fluorenyl groups. The presence of the sterically congested fluorene groups imparts BFAn with a high thermal decomposition temperature (T d ¼ 510 C) and results in its forming a stable glass (T g ¼ 227 C). Atomic force microscopy measurements revealed that BFAn forms high-quality amorphous films and possesses good morphological stability after annealing. Organic light-emitting diodes (OLEDs) featuring BFAn as the emitter exhibited an excellent external quantum efficiency of 5.1% (5.6 cd A À1) with Commission Internationale de L'Eclairage coordinates of (0.15, 0.12) that are very close to the National Television Standards Committee's blue standard. The power efficiency of our BFAn-based devices reached as high as 5.7 lm W À1 , making them superior to other reported non-doped deep-blue OLEDs.
Chemistry - A European Journal, 2011
We present here a cruciform oligo(phenylenevinlyene) 2,5,2′,5′-tetrastyrylbiphenyl (TSB) exhibits excellent properties as host material for blue emitting guest molecule 1,4-di(4′-N,N-diphenylaminostyryl)benzene (DPA-DSB). TSB, which is constructed by linking two rigid distyrylbenzene (DSB) through the phenyl-phenyl bond, shows good optical and electronic properties e.g. high photoluminescent (PL) efficiency and wide band gap similar to DSB. Meanwhile, the central biphenyl core in TSB, which allows the relatively free rotation of two DSB segments along the biphenyl bond, makes it to be conformational multiformity and relatively flexible. As the result, TSB shows the good film forming property and larger loading ability to the guest molecules. The PL efficiencies of guest-host films of DPA-DSB and TSB arrive at the high level around 70% (68% for the 2 wt % DPA-DSB doped film and 72% for the 8 wt % DPA-DSB doped film), which is approaching the PL efficiency of the guest DPA-DSB in dilute solution (78%), indicating that the host TSB can sufficiently disperse the guest DPA-DSB with little aggregation. The organic light-emitting devices using DPA-DSB (2 wt %) doped TSB as blue emitting layer show the maximum efficiency of 12.2 cd/A (6.2%) and 6.39 lm/W, and the maximum brightness of 17350 cd/m 2 . Upon further analysis, it has been revealed that the Förster energy transfer and charge trapping are demonstrated to cooperatively work in this doping system.
Synthesis and properties of blue-light-emitting anthracene derivative with diphenylamino-fluorene
Dyes and Pigments, 2010
a b s t r a c t 9,10-Bis-(9 0 ,9 0 -diethyl-7 0 -diphenylamino-fluoren-2-yl)-anthracene was synthesized from 9.10-anthracene diboronic acid and (7-bromo-9,9-diethyl-fluoren-2-yl)-diphenyl-amine in a Suzuki coupling reaction. A theoretical calculation of the three-dimensional structure suggests that it has a non-coplanar structure and inhibited intermolecular interactions. Upon excitation, the photoluminescence maximum of 9,10-bis-(9 0 ,9 0 -diethyl-7 0 -diphenylamino-fluoren-2-yl)-anthracene in solution and film were at 454 nm (solution) and 462 nm (film). The full width at half maximum of 9,10-bis-(9 0 ,9 0 -diethyl-7 0 -diphenylamino-fluoren-2yl)-anthracene is 54 nm regardless of whether it is in a solution or a solid state. A multi-layered device using 9,10-bis-(9 0 ,9 0 -diethyl-7 0 -diphenylamino-fluoren-2-yl)-anthracene as emitting material exhibits maximum quantum efficiency of 3.3% (power efficiency of 2.1 lm/W, current efficiency of 4.17 cd/A) and a blue Commission Internationale de l'Eclairage chromaticity coordinates (x ¼ 0.14, y ¼ 0.17).
1,5-, 2,6- and 9,10-distyrylanthracenes as luminescent organic semiconductors
Journal of Materials Chemistry C, 2013
We report the synthesis, molecular and crystal structures, optoelectronic properties and organic field-effect transistor (OFET) studies of three isomeric distyrylanthracene derivatives 2,6-DPSAnt, 1,5-DPSAnt and 9,10-DPSAnt. The analysis of the structure-property relationships reveals that p-conjugation in this series is defined by two competing factors: the co-planarity of the styryl substituents (highest in 2,6-DPSAnt) and the electronic communication through the anthracene core (strongest in 9,10-DPSAnt).