Spirally configured cis-stilbene/fluorene hybrid materials for organic light-emitting diode

Abstract

The present invention provides a series of spirally configured cis-stilbene/fluorene hybrid materials, which are spirally-configured cis-stilbene/fluorene derivatives having glass transition temperatures ranged from 105 C. to 130 C., decomposition temperatures ranged from 385 C. to 415 C., reversible electron transport property, and balanced charges motilities. Moreover, a variety of experimental data have proved that the yellow fluorescent, the green phosphorescent, the yellow phosphorescent, and the red phosphorescent OLEDs using this spirally configured cis-stilbene/fluorene derivatives as the electron transport layers having hole blocking functions can indeed show excellent EQE, current efficiency, power efficiency, maximum luminance, and device lifetime performances much better than the conventional or commercial yellow fluorescent, green phosphorescent, yellow phosphorescent, and red phosphorescent OLEDs.

Claims

1. A spirally configured cis-stilbene/fluorene hybrid material for OLED device, wherein the spirally configured cis-stilbene/fluorene hybrid material is spirally-configured cis-stilbene/fluorene compound having the function to block holes and constructed by at least one cis-Stilbene based component and at least one fluorene based component, wherein the spirally configured cis-stilbene/fluorene hybrid material is represented by following chemical formula V: ##STR00011## wherein, R is hydrogen group or tert-butyl group.

2. The spirally configured cis-stilbene/fluorene hybrid material of claim 1, having glass transition temperatures (T.sub.g) ranged from 105 C. to 130 C. and decomposition temperatures (T.sub.d) ranged from 385 C. to 415 C.

3. The spirally configured cis-stilbene/fluorene hybrid material of claim 1, having highest occupied molecular orbital energy level (E.sub.HOMO) ranged from 5.4 eV to 6.3 eV and lowest unoccupied molecular orbital energy level (E.sub.LUMO) ranged from 2.7 eV to 3.4 eV.

4. The spirally configured cis-stilbene/fluorene hybrid material of claim 1, capable of being applied in the OLED device for being as an electron transport layer and/or a hole blocking layer.

5. The spirally configured cis-stilbene/fluorene hybrid material of claim 1, capable of being applied in a solar cell for being as a carrier transport layer.

6. The spirally configured cis-stilbene/fluorene hybrid material of claim 1, having oxidation potentials ranged from 0.45V to 1.03V and redox potentials ranged from 1.57V to 2.32V.

7. The spirally configured cis-stilbene/fluorene hybrid material of claim 1, wherein the spirally configured cis-stilbene/fluorene hybrid material is represented by following chemical formula V-1: ##STR00012## wherein R is hydrogen group or tert-butyl group.

8. The spirally configured cis-stilbene/fluorene hybrid material of claim 1, wherein the spirally configured cis-stilbene/fluorene hybrid material is represented by following chemical formula V-2: ##STR00013## wherein R is hydrogen group or tert-butyl group.

9. The spirally configured cis-stilbene/fluorene hybrid material of claim 1, wherein the spirally configured cis-stilbene/fluorene hybrid material is represented by following chemical formula V-3: ##STR00014## wherein R is hydrogen group or tert-butyl group.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention as well as a preferred mode of use and advantages thereof will be best understood by referring to the following detailed description of an illustrative embodiment in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 is a framework view of a conventional organic light emitting diode (OLED).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) To more clearly describe spirally configured cis-stilbene/fluorene hybrid materials for OLEDs according to the present invention, embodiments of the present invention will be described in detail with reference to the attached drawings hereinafter.

(4) The present invention provides a spirally configured cis-stilbene/fluorene hybrid material for OLEDs. The spirally configured cis-stilbene/fluorene hybrid material, constructed by at least one cis-Stilbene based component and at least one fluorene based component, is a spirally-configured cis-stilbene/fluorene derivative having the functionality to block holes. This spirally configured cis-stilbene/fluorene hybrid material is mainly applied in an OLED for being as an electron transport layer and/or a hole blocking layer; moreover, this spirally configured cis-stilbene/fluorene hybrid material can also be applied in a solar cell for being as a carrier transport layer.

(5) In the present invention, the said spirally-configured cis-stilbene/fluorene derivative is represented by following chemical formula I:

(6) ##STR00006##

(7) In the chemical formula I, R1 is diphenylamino (NPh.sub.2), and R2 is the following chemical formula I-1, chemical formula I-2-1, chemical formula I-2-2, or chemical formula I-3. Moreover, R3 is the following chemical formula I-4 (i.e., hydrogen group) or chemical formula I-4 (i.e., tert-butyl group).

(8) ##STR00007##

(9) To manufacture the spirally configured cis-stilbene/fluorene hybrid material of the present invention, a key intermediate product needs to be firstly fabricated by using following steps: (1) dissolving 30 mM 2-Bromobiphenyl of 5.2 mL in 100 mL of anhydrous tetrahydrofuran (THF); (2) placing the solution obtained from the step (1) in an environment of 78 C. for standing; (3) taking 12 mL of butyllithium hexanes solution (30 mM) from a n-butyllithium solution 2.5 M in hexanes, and then adding the 12 mL butyllithium hexanes solution dropwise into the solution obtained from the step (2) and stirring for 30 min; (4) dissolving 20 mM 3,7-dibromo-dibenzosuberenone of 7.28 g in 60 mL of anhydrous THF; (5) adding the solution obtained from step-4 to the reaction mixture in step-3 dropwise; (6) adding 10 mL of saturated aqueous sodium bicarbonate solution into the product obtained from the step (5) for executing a quenching reaction, and then remove the THF by rotary evaporation; (7) treating the product obtained from the step (6) with a extracting process by using dichloromethane, and then obtaining a liquid extract; (8) adding 5 g magnesium sulfate into the liquid extract, and then treat a drying process and a filtering process to the liquid extract sequentially; and (9) using a rotary evaporating process to the product obtained from the step (8), so as to obtain an intermediate product.

(10) Furthermore, the following steps can be used for making another intermediate product to clear crystalline material. (10) dissolving the intermediate product from step (9) in 60 m acetic acid; (11) adding 1 mL of concentrated hydrochloric acid (12 N) into the solution obtained from the step (10); (12) letting the solution mixture obtained from the step (11) to react for 2 hours at 120 C. by using a reflux device; (13) cooling the temperature of the product obtained from the step (12) down to 0 C.; (14) adding 60 mL hexane into the product obtained from the step (13); (15) using a Buchner funnel to treat the product obtained from the step (14) with a filtering process, so as to obtain a precipitate; (16) using hexane to wash the precipitate for 3 times, so as to obtain a solid material; (17) using dichloromethane/hexane to treat the solid with a recrystallization process for obtaining clear crystal solid, wherein the clear crystal solid is presented by following chemical formula 1.

(11) ##STR00008##

(12) Furthermore, various exemplary embodiments for the spirally configured cis-stilbene/fluorene hybrid material of the present invention can be fabricated by treating certain chemical reaction method to the key intermediate product of clear crystalline materials represented by the chemical formula 1, such as Hartwig reaction and Rosemund-VonBarann method. Therefore, the exemplary embodiments 1-4 of the spirally configured cis-stilbene/fluorene hybrid materials are represented by following chemical formula II, chemical formula III, chemical formula IV, or chemical formula V:

(13) ##STR00009##

(14) In the chemical II-V, R can be hydrogen group or tert-butyl group. Moreover, the data of glass transition temperature (T.sub.g), decomposition temperature (T.sub.d), the longest peak wavelength value of absorption spectrum (.sub.max), and the longest peak wavelength value of photoluminescence spectrum (PL .sub.max) are measured and recorded in the following Table (1). From the Table (1), it is able to know that the spirally configured cis-stilbene/fluorene hybrid materials proposed by the present invention has glass transition temperatures (T.sub.g) ranged from 105 C. to 130 C. and decomposition temperatures (T.sub.d) ranged from 385 C. to 415 C. That means these spirally configured cis-stilbene/fluorene hybrid materials possess excellent thermal stability, and are not easy to decompose under high voltage and high current density operation conditions.

(15) TABLE-US-00001 TABLE (1) T.sub.g T.sub.d .sub.max PL.sub.max Group ( C.) ( C.) (nm) (nm) Embodiment 1 105 390 420 519 (NSCN) Embodiment 2 130 385 410 523 (NSCN) Embodiment 3 110 415 344 413 (CNSCN) Embodiment 4 121 405 365 423 (CNSCN)

(16) Moreover, the oxidation potential and the redox potential of the embodiments 1-4 of the spirally configured cis-stilbene/fluorene hybrid materials can be measured by way of cyclic voltammetry (CV); therefore, the highest occupied molecular orbital energy level (E.sub.HOMO) and lowest unoccupied molecular orbital energy level (E.sub.LUMO) of the embodiments 1-4 of the spirally configured cis-stilbene/fluorene hybrid materials can also be calculated based on the measured oxidation potential (E.sub.1/2.sup.ox) and the redox potential (E.sub.1/2.sup.red). With reference to following Table (2), E.sub.1/2.sup.ox, E.sub.1/2.sup.red, E.sub.HOMO, and E.sub.LUMO of the spirally configured cis-stilbene/fluorene hybrid materials are recorded. From the Table (2), we are able to know that the spirally configured cis-stilbene/fluorene hybrid materials proposed by the present invention have the E.sub.HOMO ranged from 5.4 eV to 6.3 eV and the E.sub.LUMO ranged from 2.7 eV to 3.4 eV. Moreover, the spirally configured cis-stilbene/fluorene hybrid materials also have the oxidation potentials ranged from 0.45 V to 1.03 V and the redox potentials ranged from 1.57 V to 2.32 V.

(17) TABLE-US-00002 TABLE (2) E.sub.1/2.sup.ox E.sub.1/2.sup.red Eg E.sub.HOMO E.sub.LUMO Group (V) (V) (eV) (eV) (eV) Embodiment 0.48 2.20 2.68 5.4 2.8 1 (NSCN) Embodiment 0.45 1.57 2.37 5.4 2.7 2 (NSCN) Embodiment 1.90 3.22 6.3 3.1 3 (CNSCN) Embodiment 1.03 2.32 3.04 6.2 3.4 4 (CNSCN)

(18) In order to prove that the proposed spirally configured cis-stilbene/fluorene hybrid materials can indeed be applied in OLEDs for being as an electron transport layer and/or a hole blocking layer, a plurality of OLED devices for control groups and experiment groups have been designed and manufactured, wherein the constituting layers for the OLED devices are integrated in the following Table (3).

(19) TABLE-US-00003 TABLE (3) electron hole Light Hole Device bottom transport blocking emitting transport top Group substrate electrode layer layer layer layer electrode Experiment Al LiF NSCN BCP yellow NPB Al 1 fluorescent Experiment Al LiF NSCN BCP yellow NPB ITO 2 fluorescent Control Al LiF Alq.sub.3 BCP yellow NPB ITO 1 fluorescent Experiment Al LiF NSCN BCP red TAPC HIL/ITO 3 phosphorescent Control Al LiF TPBi BCP yellow TAPC HIL/ITO 2 fluorescent Experiment Al LiF NSCN BmPyPb yellow TAPC HIL/ITO 4 phosphorescent Control Al LiF Alq.sub.3 BmPyPb yellow TAPC HIL/ITO 3 phosphorescent Experiment Al LiF NSCN NSCN green TAPC HIL/ITO 5 phosphorescent Experiment Al LiF CNSCN CNSCN green TAPC HIL/ITO 6A phosphorescent Control Al LiF BmPyPb BmPyPb green TAPC HIL/ITO 4A phosphorescent Control Al LiF DPyPA DPyPA green TAPC HIL/ITO 4B phosphorescent Control Al LiF TPBi TPBi green TAPC HIL/ITO 4C phosphorescent Control Al LiF Alq.sub.3 Alq.sub.3 green TAPC HIL/ITO 4D phosphorescent Experiment Al LiF NSCN NSCN green NPB/HT01 HIL/ITO 7 phosphorescent Control Al LiF BmPyPb BmPyPb green NPB/HT01 HIL/ITO 5 phosphorescent Control Al LiF ET 01 ET 01 green NPB/HT01 HIL/ITO 6 phosphorescent

(20) In the Table (3), BCP is the abbreviation of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, BmPyPb is the abbreviation of 1,3-bis(3,5-dipyrid-3-yl-phenyl)benzene, DPyPA is the abbreviation of 9,10-bis(3-(pyridin-3-yl)phenyl)anthracene, TPBi is the abbreviation of 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene, and Alq.sub.3 is the abbreviation of tris(8-hydroxyquinoline) aluminium(iii). In addition, ET 01 is represented by following chemical formula 2.

(21) ##STR00010##

(22) From the Table (3), it is able to know that the materials of Alq.sub.3, TPBi, BmPyPb, and ET 01 records in the Table (3) are also used as OLED device's electron transport layers. Continuously, the turn-on voltage (V.sub.on), the external quantum efficiency (.sub.ext), the current efficiency (.sub.c), the power efficiency (.sub.p), and the maximum luminance (L.sub.max) of the OLED devices have been measured and recorded in the following Table (4).

(23) TABLE-US-00004 TABLE (4) Device .sub.max Von .sub.ext .sub.c/.sub.p L.sub.max Group (nm) (V) (%) (%) (cd/m.sub.2) Experiment 586 3.3 4.2 12.3/6.3 32400 1 Experiment 586 3.6 5.0 10.6/4.8 22830 2 Control 581 3.4 2.7 7.1/3.6 16660 1 Experiment 624 3.4 20.6 18.5/14.7 9671 3 Control 620 3.4 16.1 15.8/12.2 5820 2 Experiment 582 2.6 24.8 78.2/79.6 78350 4 Control 583 3.0 18.6 60.2/53.6 49030 3 Experiment 520 2.9 17.0 59.1/64.1 102600 5 Experiment 516 3.0 12.0 36.4/27.6 115800 6A Control 516 2.5 6.3 22.8/18.0 142100 4A Control 516 3.0 10.2 37.8/24.0 40700 4B Control 516 3.0 6.9 24.7/22.0 37640 4C Control 516 2.8 3.4 11.5/9.7 42140 4D Experiment 516 5.5 12.6 43.1/24.6 22450 7 Control 516 4.5 10.8 36.8/25.7 42150 5 Control 516 5.5 9.9 33.5/19.1 25700 6

(24) With reference to the measured data of the yellow fluorescent OLED devices in the Table (4), one can find that the yellow fluorescent OLED devices of Experiment 1 and Experiment 2 show excellent .sub.ext, .sub.c, .sub.p, and L.sub.max and is much superior to the yellow fluorescent OLED device of Control 1.

(25) Next, please refer to the measured data of the red phosphorescent OLED devices in the Table (4). The measured data obvious reveal that the red phosphorescent OLED devices of Experiment 3 show excellent .sub.ext, .sub.p, and L.sub.max and is much superior to the red phosphorescent OLED device of Control 2.

(26) Continuously referring to the measured data of the yellow phosphorescent OLED devices in the Table (4), it can also find that the yellow phosphorescent OLED devices of Experiment 4 show excellent .sub.ext, .sub.c, .sub.p, and L.sub.max and is much superior to the yellow phosphorescent OLED device of Control 3.

(27) Eventually, please refer to the measured data of the green phosphorescent OLED devices in the Table (4). The measured data reveal that the green phosphorescent OLED devices of Experiment 5 and Experiment 6A show excellent .sub.ext, .sub.p, and L.sub.max and are superior to the green phosphorescent OLED device of Control 4A, Control 4B, Control 4C, and Control 4D. Moreover, the green phosphorescent OLED devices of Experiment 7 shows excellent .sub.ext, .sub.p, and L.sub.max and is superior to the green phosphorescent OLED device of Control 5 and Control 6.

(28) Furthermore, device life time evaluation test for the green phosphorescent OLEDs have also been completed based on a starting luminance of 10,000 cd/cm.sup.2. Life time evaluation test results reveal that the decay half lifetime (LT.sub.50) of the green phosphorescent OLED of Experiment 5 is 19,000 hours. In addition, the decay half lifetime (LT.sub.50) of the green phosphorescent OLEDs of Control 4A and Control 6 are respectively 1,000 hours and 20,000 hours. Moreover, after replacing the BmPyPb in the green phosphorescent OLEDs of Control 4A by the TmPyPb, the green phosphorescent OLEDs having the TmPyPb material is measured with the LT.sub.50 of only 210 hours.

(29) Therefore, through above descriptions, the spirally configured cis-stilbene/fluorene hybrid materials for OLEDs proposed by the present invention have been introduced completely and clearly; in summary, the present invention includes the advantages of: (1) The spirally configured cis-stilbene/fluorene hybrid materials are spirally-configured cis-stilbene/fluorene derivatives having the functions to block holes and constructed by at least one cis-Stilbene based component and at least one fluorene based component, which include glass transition temperatures ranged from 105 C. to 130 C., decomposition temperatures ranged from 385 C. to 415 C., reversible electron transport property, and balanced charges motilities. (2) Moreover, a variety of experimental data have proved that the yellow fluorescent, the green phosphorescent, the yellow phosphorescent, and the red phosphorescent OLEDs using this spirally configured cis-stilbene/fluorene derivatives as the electron transport layers having hole blocking functions can indeed show excellent EQE, current efficiency, power efficiency, maximum luminance, and device lifetime performances better than the conventional or commercial yellow fluorescent, green phosphorescent, yellow phosphorescent, and red phosphorescent OLEDs.

(30) The above description is made on embodiments of the present invention. However, the embodiments are not intended to limit scope of the present invention, and all equivalent implementations or alterations within the spirit of the present invention still fall within the scope of the present invention.