Patent Application
20150137083
1. Field of the Invention
The present invention relates to a conjugated aromatic derivative and an organic light emitting diode (OLED), and more particularly to a conjugated aromatic derivative having an electron donating group and an electron accepting group at each end and organic light emitting diode using the same.
2. Description of the Prior Art
OLED (organic light-emitting diode), also commonly known as organic electroluminescent device, is a kind of LED having an organic layer as the active layer. OLED has been spotlighted due to a lot of advantages, such as self illumination, wider visual angle (>170°), shorter response time (˜μs), higher contrast, higher efficiency, lower power consumption, higher brightness, lower operative voltage (3-10V), thinner size (<2 mm), flexibility and so on. In recent years, OLED has been gradually used in flat panel display. In comparison to LCD monitor, OLED displays are provided with OLED pixel array having self-luminous characteristics and therefore do not require additional back light module. To apply OLED into a full-color display, it is necessary and important to develop red, green, and blue light emitting materials with appropriate chromaticity and high light-emitting efficiency.
Excitons generated from recombining holes and electrons have triplet state or singlet state for its spin state. Singlet exciton relaxation radiates fluorescence and triplet exciton relaxation radiates phosphorescence. Phosphorescence achieves 3-fold efficiency comparing to fluorescence and may greatly enhance the IQE (internal quantum efficiency) of devices up to 100% by adopting metal complexes in electroluminescent configuration to achieve strong spin-orbital coupling and mixing of singlets and triplets. Therefore, phosphorescent metal complexes are now adopted as phosphorescent dopants in the emitting layer of OLED.
In addition, by using a doping method in the emitting layer, self-quenching of the emitting materials can be reduced greatly to enhance the efficiency of the device. Therefore, the search for proper host materials becomes noteworthy since host materials must be capable of capturing carriers and have good energy transfer properties, high glass transition temperature, high thermal stability and appropriate energy gap of the singlet and triplet excited states. However, it would be difficult to search for host materials that fully meet the criteria and there is still some room for host material development in OLED.
The hunt for efficient blue electroluminescence is of particular interest because it is an essential component to realize OLEDs in display as well as lighting applications. Many research groups have successfully prepared efficient blue fluorophores and their OLEDs. However, at the present time, the efficient ones with good Commission Internationale d'Enclairage y coordinate value (CIEy)≦0.15 are still relatively rare. At the present time, there is a lack of good organic electroluminescence compounds that will satisfy the aforementioned need.
To sum up, it is highly desirable to develop novel and efficient electroluminescent materials in blue color spectrum.
The present invention is directed to providing novel conjugated aromatic derivatives.
According to one embodiment, a conjugated aromatic derivative having a chemical formula represented by formula (I):
Here, m is an integer ranging from 0 to 5, n is an integer ranging from 0 to 5, each of R1 and R2 is independently selected from the group consisting of hydrogen, C1 to C6 alkyl group, aryl group.
When n=1 to 5, substituent A is selected from the group consisting of substituted or unsubstituted pyrene, substituted or unsubstituted phosphine oxide, substituted or unsubstituted sulfonyl and substituted or unsubstituted benzothiadiazole.
When n=0, substituent A is substituted or unsubstituted benzothiadiazole.
When m=1 to 5, substituent D is selected from the group consisting of substituted or unsubstituted amino group, substituted or unsubstituted imidazole, substituted or unsubstituted carbazole and substituted or unsubstituted
When m=0, substituent D is substituted or unsubstituted
substituted or unsubstituted
or, substituted or unsubstituted
wherein each of the substituents of substituent D or substituent A is independently selected from the group consisting of halogen, aryl group, C1-C20 alkenyl, C1-C20 alkyl, C1-C20 alkynyl, cyano, CF3, alkylamino, amino, alkoxy, heteroaryl, halogen substituted aryl group, halogen substituted aralkyl group, haloalkyl substituted aryl group, haloalkyl substituted aralkyl group, aryl substituted C1-C20 alkyl group, cycloalkyl group, C1-C20 alkoxy group, C1-C20 alkyl substituted amino group, haloalkyl substituted amino group, aryl substituted amino group, heteroaryl substituted amino group, aryl substituted phosphine oxide, C1-C20 alkyl substituted phosphine oxide, haloalkyl substituted phosphine oxide, halogen substituted phosphine oxide, heteroaryl substituted phosphine oxide, nitro group, carbonyl group, aryl substituted carbonyl group, heteroaryl substituted carbonyl group and halogen substituted C1-C20 alkyl group.
The present invention is also directed to providing an OLED device with high efficiency and performance.
According to another embodiment, an organic light emitting diode includes a cathode, an anode and an organic layer configured between the cathode and the anode and comprising the aforementioned conjugated aromatic derivative.
The conjugated aromatic derivative of the present invention may be provided with blue light-emitting property and used as a host emitter material or a guest emitter material. The conjugated aromatic derivative of the present invention may also be configured as an electron transport material or a hole transport material.
Other advantages of the present invention will become apparent from the following descriptions taken in conjunction with the accompanying drawings wherein certain embodiments of the present invention are set forth by way of illustration and examples.
The foregoing aspects and many of the accompanying advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed descriptions, when taken in conjunction with the accompanying drawings, wherein:
The present invention is directed to providing a conjugated aromatic derivatives used as blue fluorescent material having a chemical formula represented by formula (I):
Here, m is an integer ranging from 0 to 5, n is an integer ranging from 0 to 5.
Each of R1 and R2 is independently selected from the group consisting of hydrogen, C1 to C6 alkyl group, aryl group, wherein the aryl group of R1 and R2 is C5 to C8, preferably.
The chemical formula of conjugated aromatic derivatives of the present invention may be represented by formula (II) to (IV):
Substituent A denotes electron accepting group. When n=1 to 5, substituent A is selected from the group consisting of substituted or unsubstituted pyrene, substituted or unsubstituted phosphine oxide, substituted or unsubstituted sulfonyl and substituted or unsubstituted benzothiadiazole.
When n=0, substituent A is substituted or unsubstituted benzothiadiazole.
Some examples of substituent A are listed as follows, such as pyrene, diphenyl phosphine oxide, phenyl sulfonyl and phenyl benzothiadiazole.
Substituent D denotes electron donating group.
When m=1 to 5, substituent D is selected from the group consisting of substituted or unsubstituted amino group, substituted or unsubstituted imidazole, substituted or unsubstituted carbazole and substituted or unsubstituted
When m=0, substituent D is substituted or unsubstituted
substituted or unsubstituted
or, substituted or unsubstituted
In one embodiment, substituent D is selected from the group consisting of follows:
Each of the substituents of substituent D or substituent A is independently selected from the group consisting of halogen, aryl group, C1-C20 alkenyl, C1-C20 alkyl, C1-C20 alkynyl, cyano, CF3, alkylamino, amino, alkoxy, heteroaryl, halogen substituted aryl group, halogen substituted aralkyl group, haloalkyl substituted aryl group, haloalkyl substituted aralkyl group, aryl substituted C1-C20 alkyl group, cycloalkyl group, C1-C20 alkoxy group, C1-C20 alkyl substituted amino group, haloalkyl substituted amino group, aryl substituted amino group, heteroaryl substituted amino group, aryl substituted phosphine oxide, C1-C20 alkyl substituted phosphine oxide, haloalkyl substituted phosphine oxide, halogen substituted phosphine oxide, heteroaryl substituted phosphine oxide, nitro group, carbonyl group, aryl substituted carbonyl group, heteroaryl substituted carbonyl group and halogen substituted C1-C20 alkyl group.
The term “aryl” refers to a C6 to C30 hydrocarbon moiety having one or more aromatic rings. Examples of aryl moieties include phenyl (Ph), phenylene, naphthyl, naphthylene, pyrenyl, anthryl, and phenanthryl.
The term “heteroaryl” refers to a C5 to C10 moiety having one or more aromatic rings that contain at least one heteroatom (e.g., N, O, or S). Examples of heteroaryl moieties include furyl, furylene, fluorenyl, pyrrolyl, thienyl, oxazolyl, imidazolyl, thiazolyl, pyridyl, pyrimidinyl, quinazolinyl, quinolyl, isoquinolyl and indolyl.
Alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, and heteroaryl mentioned herein include both substituted and unsubstituted moieties, unless specified otherwise. Possible substituents on cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, and heteroaryl include, but are not limited to, C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C20 cycloalkyl, C3-C20 cycloalkenyl, C1-C20 heterocycloalkyl, C1-C20 heterocycloalkenyl, C1-C10 alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, amino, C1-C10 alkylamino, C1-C20 dialkylamino, arylamino, diarylamino, C1-C10 alkylsulfonamino, arylsulfonamino, C1-C10 alkylimino, arylimino, C1-C10 alkylsulfonimino, arylsulfonimino, hydroxyl, halo, thio, C1-C10 alkylthio, arylthio, C1-C10 alkylsulfonyl, arylsulfonyl, acylamino, aminoacyl, aminothioacyl, amido, amidino, guanidine, ureido, thioureido, cyano, nitro, nitroso, azido, acyl, thioacyl, acyloxy, carboxyl, and carboxylic ester. On the other hand, possible substituents on alkyl, alkenyl, or alkynyl include all of the above-recited substituents except C1-C10 alkyl. Cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, and heteroaryl can also be fused with each other.
Refer to the above scheme illustrating the synthesis of compounds of the present invention, wherein substituent D of the formula of the present invention correspond to an amine group and a carbazole group.
It is noted that the substituent D of derivatives having different number of benzene rings may be obtained by adjusting the correspondent number of benzene rings of the starting material 1-bromo-4-(bromomethyl)benzene.
Refer to the above scheme illustrating the synthesis of compounds of the present invention, wherein substituent D of the formula of the present invention corresponds to a carbazole group or
It is noted that the substituent D of derivatives having different number of benzene rings may be obtained by adjusting the correspondent number of benzene rings of the starting material 4-bromobenzaldehyde.
Some examples of the compounds of the present invention are listed as follows.
(E)-4-(4-bromostyryl)-N, N-diphenylaniline (0.43 g, 1 mmol) was added into the two-neck flask, followed by addition of THF 20 mL, and then cooled to −78° C. nBuLi (1.2 mmol) was added dropwise and stirred at low temperature for 1 hour. Chlorodiphenylphosphine (0.19 ml, 1 mmol) was slowly added and slowly warmed to room temperature for 8 hours reaction. Hydrochloric acid solution (2M) was then added. The mixture was then extracted with dichloromethane, and the organic layer were oxidized by adding hydrogen peroxide under an ice bath for 8 hours, then extracted with dichloromethane. The solvent was removed and purified by column chromatography to obtain the product (63%).
1H NMR (400 MHz, CDCl3), δ (ppm): 7.69-7.60 (m, 6H) 7.58-7.51 (m, 3H) 7.47-7.43 (m, 3H) 7.36 (d, J=8.0, 2H) 7.28-7.22 (m, 5H) 7.15-7.08 (m, 5H) 7.07-6.94 (m, 6H)
(E)-(4-(4-(diphenylamino) styryl)phenyl) boronic acid (0.94 g, 2.4 mmol), (4-bromophenyl)diphenylphosphine oxide (0.71 g, 2.0 mmol), Pd(PPh3)4 (0.1 g, 5 mol %), potassium carbonate (0.97 g) were added into 25 ml two-necked flask and toluene 10.5 ml, EtOH 3.5 ml, DI water 3.5 ml were added into flask, then heated to 90 degrees for 12 hour reaction. After completion of reaction, the solvent was removed and the reactants was filtered with Celite and purified by column chromatography to obtain the product (73%).
1H NMR (400 MHz, CDCl3), δ (ppm): 7.74-7.67 (m, 8H), 7.6-7.52 (m, 6H) 7.49-7.44 (m, 4H) 7.38 (d, J=8.0, 2H) 7.27-7.22 (m, 4H) 7.13-7.08 (m, 4H) 7.06-6.98 (m, 6H)
(E)-4-(4-bromostyryl)-N, N-diphenylaniline (0.21 g, 0.5 mmol), thiophenol (0.056 mL, 0.55 mmol), NaOtBu (0.21 g, 2.2 mmol), Pd(PPh3)4 (0.058 g, 1 mol %), PPh3 (0.052 g, 0.2 mmol), BuOH (30 mL) were placed into a two-neck flask and heated to reflux for 18 hours. The reactant was filtered with Celite and solvent were removed by rotary evaporation, and then purified by flash column chromatography. The collected compound was dissolved in acetic acid and hydrogen peroxide was added to undergo oxidation reaction for 5 hours, and the crude was then purified by column chromatography to obtain the product (65%).
1H NMR (400 MHz, CDCl3), δ (ppm): 7.95-7.93 (m, 2H), 7.88 (d, J=8.0, 2H) 7.56-7.46 (m, 5H) 7.35 (d, J=8.0, 2H) 7.29-7.23 (m, 4H) 7.14-7.08 (m, 5H) 7.06-6.91 (m, 5H)
Similar with the synthesis method of DASPPO, (4-bromophenyl)diphenylphosphine oxide was replaced with 1-bromo-4-(phenylsulfonyl)benzene, yield=70%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.00-7.96 (m, 4H) 7.72-7.69 (m, 2H) 7.58-7.49 (m, 7H) 7.38 (d, J=8.0, 2H) 7.27-7.22 (m, 4H) 7.12-6.97 (m, 10H)
Similar with the synthesis method of DASPO, (E)-4-(4-bromostyryl)-N, N-diphenylaniline was replaced with (E)-3-(4-bromostyryl)-9-ethyl-9H-carbazole, yield=60%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.23 (s, 1H) 8.11 (d, J=8.0, 1H) 7.71-7.61 (m, 8H) 7.56-7.52 (m, 2H) 7.48-7.44 (m, 4H) 7.42-7.37 (m, 4H) 7.25-7.11 (m, 3H) 4.36 (q, J=8.0, 4.0, 2H) 1.41 (t, J=4.0, 3H)
Similar with DASPPO synthesis method, (E)-(4-(4-(diphenylamino) styryl)phenyl) boronic acid was replaced with (E)-(4-(2-(9-ethyl-9H-carbazol-3-yl) vinyl)phenyl) boronic acid, yield=66%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.24 (s, 1H), 8.12 (d, J=8.0, 1H), 7.76-7.60 (m, 12H) 7.57-7.53 (m, 2H) 7.49-7.45 (m, 4H) 7.41-7.35 (m, 4H) 7.26-7.15 (m, 3H) 4.36 (q, J=8.0, 4.0, 2H) 1.43 (t, J=8.0, 3H)
Similar with DASSO synthesis method, (E)-4-(4-bromostyryl)-N, N-diphenylaniline replaced with (E)-3-(4-bromostyryl)-9-ethyl-9H-carbazole, yield=66%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.22 (s, 1H) 8.10 (d, J=8.0, 1H) 7.96-7.89 (m, 4H) 7.66-7.61 (m, 3H) 7.57-7.45 (m, 3H) 7.41-7.37 (m, 3H) 7.26-7.08 (m, 3H) 4.35 (q, J=8.0, 4.0, 2H) 1.43 (t, J=8.0, 3H)
Similar with CzSPPO synthesis method, (4-bromophenyl)diphenylphosphine oxide was replaced with 1-bromo-4-(phenylsulfonyl)benzene, yield=70%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.23 (s, 1H) 8.12 (d, J=8.0, 1H) 8.00-7.96 (m, 3H) 7.74-7.71 (m, 2H) 7.67 (dd, J=8.0, 1.2, 1H) 7.64-7.45 (m, 8H) 7.41-7.35 (m, 3H) 7.26-7.13 (m, 3H) 4.37 (q, J=8.0, 4.0, 2H) 1.44 (t, J=8.0, 3H)
(4-(2-phenyl-1H-phenanthro[9,10-d]imidazol-1-yl)benzyl)phosphonate (1.04 g, 2 mmol) and 4-(diphenylamino)benzaldehyde (0.55 g, 2 mmol) were dissolved in THF (10 ml). The mixture were then added dropwise to a solution of THF containing KOtBu (0.45 g, 4 mmol), and the mixture were reacted for 8 hours. The reaction was then poured into a large amount of water, and the precipitated was then filtered, recrystallized yield=35%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.86 (d, J=8.0, 1H) 8.76 (d, J=8.0, 1H) 8.70 (d, J=8.0, 1H) 8.28 (s, 1H) 8.14 (d, J=8.0, 1H) 7.75-7.71 (m, 4H) 7.66-7.62 (m, 3H) 7.53-7.41 (m, 6H) 7.36-7.23 (m, 8H) 4.39 (q, J=8.0, 4.0, 2H) 1.46 (t, J=8.0, 3H)
Similar with PISCz, the 4-(diphenylamino)benzaldehyde was replaced by 9-ethyl-9H-carbazole-3-carbaldehyde, yield=40%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.86 (d, J=8.0, 1H) 8.76 (d, J=8.0, 1H) 8.69 (d, J=8.0, 1H) 7.72 (t, J=8.0, 1H) 7.68-7.59 (m, 4H) 7.52 (m, 1H) 7.46-7.41 (m, 3H) 7.32-7.22 (m, 10H) 7.17-7.03 (m, 11H)
Refer to Table 1, which illustrates the absorbance and emission spectrum of the compounds of the present invention, where the conjugated aromatic derivatives are blue light-emitter.
Refer to Table 2, which illustrates the glass transition temperature and decomposition temperature of the compounds of the present invention, where the conjugated aromatic derivatives of the present invention are provided with excellent thermal stability.
Refer to Table 3, which illustrates the singlet and triplet energy of the compounds of the present invention, where the conjugated aromatic derivatives of the present invention are provided with excellent energy gap between singlet and triplet.
Refer to
In the tested electroluminescent devices, the substrate is made of ITO; tested electrode materials include LiF/Al; tested emitting materials include m-PPT (2-3-(pyren-1-yl)phenyl)triphenylene); the test electron transport materials include BCP (2,9-dimethyl-4,7-diphenyl-[1,10]phenanthroline) and Alq3 (tris(8-hydroxyquinoline)aluminum(III) which can be used for the hole blocking layer or simultaneous hole stopper layer and electron transport layer. The test hole transporting materials include NPB (4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]bipheny), and TCTA (Tris(4-carbazoyl-9-ylphenyl)amine), which can be used for the hole blocking layer or simultaneous electron blocking layer and hole transport layer.
The detailed structures of the tested devices are as follows:
1A:NPB(30)/TCTA(10)/m-PPT:PISDA(5%)(30)/BAlq(25)/LiF(1)/Al(100)
1B:NPB(30)/TCTA(10)/m-PPT:PISCz(5%)(30)/BAlq(25)/LiF(1)/Al(100)
Refer to Table 4 illustrating the device performance using the compounds of the present invention, wherein the external quantum efficiency of the apparatus 1B, 1D, 1H is greater than 8.0 and reaches 8.9, 8.3 and 8.6, respectively.
In another embodiment, the detailed structures of the tested devices are as follows:
Refer to Table 5, which illustrates the device performance using the compounds of the present invention, wherein the external quantum efficiency of the device 2C, 2F, 2H is greater than 8.0, and reaches 8.7, 8.0 and 9.3, respectively.
It was found recently that smaller gap between singlet and triplet energy levels may increase the likelihood of forming thermally activated delayed fluorescence (TADF), and the internal quantum efficiency of fluorescence may reach 100%, which is the same as phosphorescent emitters. It is therefore these compounds may greatly improve luminous efficacy and are very different from conventional fluorescent emitters having only 25% performance.
In summary, the conjugated aromatic derivatives of the present invention are provided with an electron donating group and an electron accepting group at each end. The conjugated aromatic derivatives of the present invention has a blue light-emitting property, and may be used as main material, electron transport material or hole transport material. OLED devices using the conjugated aromatic derivatives of the present invention are also provided with good performance.
While the invention can be subject to various modifications and alternative forms, a specific example thereof has been shown in the drawings and is herein described in detail. It should be understood, however, that the invention is not to be limited to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102142017 | Nov 2013 | TW | national |
