A gradient-doped white organic electroluminescent device and a preparation method thereof

Abstract

The application provides a gradient-doped white organic electroluminescent device and a preparation method thereof, which comprises a substrate, an anode layer, an anode modification layer, a hole transport layer, a first blue light-emitting layer, an orange-red light-emitting layer, a second blue light-emitting layer, an electron transport layer / hole blocking layer, a cathode modification layer and a metal cathode layer which are compounded in sequence; the first blue light-emitting layer is an organic mixed material of a blue organic light-emitting material and an organic host material with a weight ratio of 8.0%-14.0%; the orange-red light-emitting layer is an organic mixed material of an organic sensitizing material, an orange-red organic light-emitting material and an organic host material with a weight ratio of 0.1%-1.0% and 3.0%-7.0%, and the doping concentration gradient of the organic sensitizing material is 0.1%-0.3%; and the second blue light-emitting layer is an organic mixed material of a blue organic light-emitting material and an organic host material with a weight ratio of 12.0%-18.0%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field, and particularly relates to a gradient-doped white organic electroluminescent device and a preparation method thereof. BACKGROUND

[0002] An organic electroluminescent device is a double-carrier injection type device. Under the action of an external electric field, holes and electrons are injected into an organic functional layer from an anode and a cathode, respectively. The electrons and holes meet in a light-emitting layer and recombine to form excitons. Subsequently, the excitons undergo radiative transition, and then light is generated. Due to high efficiency, low operating voltage, and flexibility, the organic electroluminescent device has attracted widespread attention from academia and industry. Among them, the white organic electroluminescent device has a huge application prospect in full-color display and solid-state lighting due to its low power consumption, no harmful ultraviolet light, wide viewing angle, and other advantages, and has become a research hotspot. In recent years, with the rapid development of material synthesis and device engineering, the luminous performance of the white organic electroluminescent device has been continuously improved. In the field of lighting applications, in addition to high brightness and high efficiency, the white organic electroluminescent device should also have excellent white light quality, such as balanced color coordinates, high color rendering index, and appropriate color temperature; in the field of display, due to the high sensitivity of the human eye to color drift, the white organic electroluminescent device needs to have high color stability, and the color coordinate change of the white organic electroluminescent device should be controlled within ±0.01.

[0003] In order to meet the industrialization needs of the white organic electroluminescent device, many research teams at home and abroad have started from material synthesis and device optimization, and have greatly improved the color stability of the white organic electroluminescent device. For example, in 2011, Professor Wang Yue of Jilin University et al. doped orange light materials in the blue light-emitting layer by gradient, and designed a white organic electroluminescent device with a single light-emitting layer structure. Although the device shows ideal white light emission, the carrier recombination region in the single light-emitting layer device is narrow, and the high exciton concentration leads to serious exciton annihilation, which in turn makes the efficiency of the device low. In the same year, Lin Huaping et al. of Shanghai University doped green light materials and red light materials in a double light-emitting layer device with blue light materials as the main body, and the red light materials in the double light-emitting layer have different doping concentrations. Although the white light quality of this device has been improved, the short intermolecular distance of the blue light materials in the double light-emitting layer structure with blue light materials as the main body leads to serious concentration annihilation, which makes the brightness and efficiency of the device difficult to meet the requirements. In addition, the low carrier mobility of the blue light materials also leads to a high operating voltage of the device.

[0004] In recent years, although the brightness and efficiency of white organic electroluminescent device have been improved to some extent, the color stability problem has not been effectively solved; at the same time, although there are some literature reports on improving color stability, it is difficult to balance high brightness and efficiency while improving color stability, so it is difficult to improve the comprehensive performance of white organic electroluminescent device. In addition, due to the poor carrier balance, the white organic electroluminescent device also shows high working voltage and serious efficiency roll-off during operation. Therefore, the development of white organic electroluminescent device still faces severe challenges, and the main problems can be summarized as follows: poor color stability, high working voltage, fast roll-off of luminous efficiency and high power consumption. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to provide a gradient-doped white organic electroluminescent device and a preparation method thereof. The prepared device has high color stability, low working voltage, power consumption and efficiency decay, and high brightness and efficiency.

[0006] To achieve the above-mentioned purpose, the present application provides a gradient-doped white organic electroluminescent device, which comprises a substrate, an anode layer, an anode modification layer, a hole transport layer, a first blue light-emitting layer, an orange-red light-emitting layer, a second blue light-emitting layer, an electron transport layer / hole blocking layer, a cathode modification layer and a metal cathode layer which are sequentially compounded.

[0007] The first blue light-emitting layer is an organic mixed material mixed by 8.0% to 14.0% of blue organic light-emitting material and organic host material by weight ratio;

[0008] The orange-red light-emitting layer is an organic mixed material mixed by 0.1% to 1.0% of organic sensitizing material, 3.0% to 7.0% of orange-red organic light-emitting material and organic host material by weight ratio, and the doping concentration gradient of the organic sensitizing material is 0.1% to 0.3%;

[0009] The second blue light-emitting layer is an organic mixed material mixed by 12.0% to 18.0% of blue organic light-emitting material and organic host material by weight ratio.

[0010] The white organic electroluminescent device provided by the present application has simple and efficient structure and low manufacturing cost. By optimizing the light-emitting material, screening the sensitizing material matched with the energy level and energy, and optimizing the device structure and preparation process, the color stability of the white organic electroluminescent device is improved, the working voltage of the device is reduced, the luminous efficiency and brightness of the device are improved, and the roll-off of the efficiency of the device is delayed

[0011] Figure 1 It is a structural schematic diagram of the white organic electroluminescent device provided by the present application. As shown in the accompanying drawings Figure 1As shown, the white organic electroluminescent device provided by the present application is sequentially connected by a substrate 1, an anode layer 2, an anode modification layer 3, a hole transport layer 4, a first blue light-emitting layer 5, an orange light-emitting layer 6, a second blue light-emitting layer 7, an electron transport layer / hole blocking layer 8, a cathode modification layer 9 and a metal cathode layer 10.

[0012] Preferably, the substrate 1 is a glass substrate.

[0013] Preferably, the anode layer 2 is preferably indium tin oxide (ITO). The surface resistance thereof is preferably 5-25 ohms.

[0014] Preferably, the anode modification layer 3 is one or more of dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexanitrile (abbreviated as HAT-CN), copper (II) phthalocyanine (abbreviated as CuPc), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (abbreviated as F4-TCNQ) and 7,7,8,8-tetracyanoquinodimethane (abbreviated as TCNQ). The molecular structures thereof are as follows I-IV, respectively:

[0015]

[0016] Preferably, the hole transport layer 4 is one or more of (including but not limited to these materials): 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)amine] (abbreviated as TAPC), tris(4-(quinolin-8-yl)phenyl)amine (abbreviated as TQTPA), N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (abbreviated as NPB) and N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine (abbreviated as TPD). The molecular structures thereof are as follows V-VIII, respectively:

[0017]

[0018] The first blue light-emitting layer 5 is preferably an organic mixed material in which the weight ratio of the blue organic light-emitting material to the organic host material is 8.0%-14.0%.

[0019] The doped blue organic light-emitting material (including but not limited to these materials) is preferably one or more of bis(4,6-difluorophenylpyridinato-N,C2)picolatoiridium (abbreviated as FIrpic) and bis[2-(5-cyano-4,6-difluorophenyl)pyridinato-C2,N)]picolatoiridium (abbreviated as FCNIrpic). The molecular structures thereof are as follows IX and X, respectively:

[0020]

[0021] The doped organic host material is preferably one or more of 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA) and 9,9'-(5-(triphenylsilyl)-1,3-phenyl)di-9H-carbazole (SimCP), whose molecular structures are as follows XI and XII, respectively:

[0022]

[0023] The orange light-emitting layer 6 is preferably an organic mixed material of 0.1% to 1.0% of an organic sensitizing material, 3.0% to 7.0% of an orange organic light-emitting material, and an organic host material, and the doping concentration gradient of the organic sensitizing material is 0.1% to 0.3%.

[0024] The doped organic sensitizing material is preferably one or more of tris(thiophenecarbonyl trifluoroacetone)phenanthroline europium (Eu(TTA)3phen) and tris(acetylacetone)phenanthroline terbium (Tb(acac)3phen), whose molecular structures are as follows XIII and XIV, respectively:

[0025]

[0026] The Eu(TTA)3phen or Tb(acac)3phen is selected as the organic sensitizing material, which is gradient-doped into the light-emitting layer to play a role of carrier deep binding center, balance the distribution of carriers, widen the light-emitting interval of the device, inhibit the color change of the white organic electroluminescent device, and improve the color stability of the device. In addition, the concentration gradient of the rare earth organic sensitizing material can form a positive built-in electric field in the light-emitting layer, thereby reducing the working voltage of the device, greatly reducing the power consumption of the device, and improving the brightness and light-emitting efficiency of the device and delaying the efficiency decay of the device.

[0027] The doped orange organic light-emitting material is preferably one or more of bis(2-phenylquinoline)(2-(3-methylphenyl)pyridine acid)iridium (III) (Ir(phq)2tpy) and bis(2-(9,9-diethyl-fluorene-2-yl)-1-phenyl-1H-benzo[d]imidazole)acetylacetone iridium (fbi)2Ir(acac)), whose molecular structures are as follows XV and XVI, respectively:

[0028]

[0029] The doped organic host material is preferably one or more of TCTA and 1,3-dicarbazol-9-ylbenzene (mCP), whose molecular structures are as follows XVII and XVIII, respectively:

[0030]

[0031] The second blue light emitting layer 7 is preferably an organic mixed material of a blue organic light emitting material and an organic host material in a weight ratio of 12.0% to 18.0%.

[0032] The doped blue organic light emitting material (including but not limited to these materials) is preferably one or more of bis(4,6-difluorophenylpyridine-N,C2)picolato iridium (abbreviated as FIrpic), bis[2-(5-cyano-4,6-difluorophenyl)pyridine-C2,N)]picolato iridium (abbreviated as FIr6), whose molecular structures are respectively as follows XIX, XX:

[0033]

[0034] The doped organic host material (including but not limited to these materials) is preferably one or more of 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole (abbreviated as CzSi), 2,6-bis[3-(9H-9-carbazolyl)phenyl]pyridine (abbreviated as 26DCzPPy), whose molecular structures are respectively as follows XXI, XXIII:

[0035]

[0036] The electron transport layer / hole blocking layer 8 is preferably one or more of (including but not limited to these materials) 1,3,5-tris(6-(3-(pyridin-3-yl)phenyl)pyridin-2-yl)benzene (abbreviated as Tm3PyP26PyB)), 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviated as TmPPPyTz), 1,3,5-tris[(3-pyridin)-3-phenyl]benzene (abbreviated as TmPyPB), or 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (abbreviated as TPBi), whose molecular structures are respectively as follows XXIII-XXVI:

[0037]

[0038] The cathode modification layer 9 is preferably lithium fluoride (LiF).

[0039] The metal cathode layer 10 is preferably metal aluminum (Al).

[0040] The anode layer 2 and the cathode layer 10 intersect with each other to form a light emitting area of the device. When a forward voltage is applied between the two electrodes, the device emits white light covering 400 to 780 nanometers.

[0041] The thickness of the anode modification layer 3 is preferably 2 to 10 nm, the thickness of the hole transport layer 4 is preferably 30 to 60 nm, the thickness of the first blue light emitting layer 5 is preferably 2 to 6 nm, the thickness of the orange-red light emitting layer 6 is preferably 4 to 10 nm, the thickness of the second blue light emitting layer 7 is preferably 6 to 12 nm, the thickness of the electron transport layer / hole blocking layer 8 is preferably 40 to 80 nm, the thickness of the cathode modification layer 9 is preferably 0.6 to 1.5 nm, and the thickness of the metal cathode layer 10 is preferably 80 to 200 nm.

[0042] The present application provides a method for preparing the above-mentioned white organic electroluminescent device, comprising the following steps:

[0043] After the glass substrate with ITO pattern is cleaned, the anode modification layer, the hole transport layer, the first blue light emitting layer, the orange-red light emitting layer, the second blue light emitting layer and the electron transport layer / hole blocking layer are successively evaporated on the ITO anode layer under the condition of vacuum degree less than 1.0 x 10 -5 After the glass substrate with ITO pattern is cleaned, the anode modification layer, the hole transport layer, the first blue light emitting layer, the orange-red light emitting layer, the second blue light emitting layer and the electron transport layer / hole blocking layer are successively evaporated on the ITO anode layer under the condition of vacuum degree less than 1.0 x 10 -6 The cathode modification layer and the metal cathode layer are successively evaporated under the condition of vacuum degree less than 1.0 x 10

[0044] Specifically, the glass substrate with ITO pattern is successively cleaned with cleaning solution and deionized water under ultrasonic for 10 to 20 minutes, and then is put into an oven for drying. Next, the dried substrate is put into a pre-treatment vacuum chamber, and then is transferred into an organic evaporation chamber. When the vacuum degree is less than 1.0 x 10 -5 The anode modification layer 3, the hole transport layer 4, the blue light emitting layer 5, the orange-red light emitting layer 6, the blue light emitting layer 7 and the electron transport layer / hole blocking layer 8 are successively evaporated on the ITO anode layer 2. Next, the unfinished device is transferred into a metal evaporation chamber, and the cathode modification layer 9 and the metal cathode layer 10 are successively evaporated under the condition of vacuum degree less than 1.0 x 10 -6 The cathode modification layer 9 and the metal cathode layer 10 are successively evaporated under the condition of vacuum degree less than 1.0 x 10

[0045] The anode and the cathode cross each other to form the light emitting area of the device. The thickness of the anode modification layer 3 is 2 to 10 nm, the thickness of the hole transport layer 4 is 30 to 60 nm, the thickness of the blue light emitting layer 5 is 2 to 6 nm, the thickness of the orange-red light emitting layer 6 is 4 to 10 nm, the thickness of the blue light emitting layer 7 is 6 to 12 nm, the thickness of the electron transport layer / hole blocking layer 8 is 40 to 80 nm, the thickness of the cathode modification layer 9 is 0.6 to 1.5 nm, and the thickness of the metal cathode layer 10 is 80 to 200 nm. The evaporation rate of HAT-CN, CuPc, F4-TCNQ and TCNQ in the anode modification layer 3 is preferably controlled at 0.01 to 0.1 nm / s, the evaporation rate of TAPC, TQTPA, NPB, TPD, TCTA, SimCP, mCP, CzSi, 26DCzPPy, Tm3PyP26PyB, TmPPPyTz, TmPyPB and TPBi in the hole transport layer 4, the blue light emitting layer 5, the orange-red light emitting layer 6, the blue light emitting layer 7, the electron transport layer / hole blocking layer 8 is controlled at 0.05 to 0.1 nm / s, the evaporation rate of Eu(TTA)3phen and Tb(acac)3phen is controlled at 0.00005 to 0.001 nm / s, the evaporation rate of the blue organic light emitting materials FIrpic, FCNIrpic and FIr6 is controlled at 0.004 to 0.02 nm / s, the evaporation rate of the orange-red organic light emitting materials Ir(phq)2tpy and (fbi)2Ir(acac) is controlled at 0.0015 to 0.007 nm / s, the evaporation rate of LiF in the cathode modification layer 9 is controlled at 0.005 to 0.015 nm / s, and the evaporation rate of Al in the metal cathode layer 10 is controlled at 0.5 to 1.5 nm / s. When the blue light emitting layer 5 is deposited, the blue organic light emitting material and the organic host material in the organic mixed material are evaporated simultaneously in different evaporation sources, and the weight ratio of the doped blue organic light emitting material and the organic host material is controlled at 8.0% to 14.0% by adjusting the evaporation rates of the two materials. When the orange-red light emitting layer 6 is deposited, the organic sensitizing material, the red organic light emitting material and the organic host material in the organic mixed material are evaporated simultaneously in different evaporation sources, and the weight ratio of the doped organic sensitizing material and the organic host material is controlled at 0.1% to 1.0% by adjusting the evaporation rates of the three materials, the concentration gradient is controlled at 0.1% to 0.3%, and the weight ratio of the doped red organic light emitting material and the organic host material is controlled at 3.0% to 7.0%. When the blue light emitting layer 7 is deposited, the blue organic light emitting material and the organic host material in the organic mixed material are evaporated simultaneously in different evaporation sources, and the weight ratio of the doped blue organic light emitting material and the organic host material is controlled at 12.0% to 18.0% by adjusting the evaporation rates of the two materials.

[0046] Compared with the prior art, the present application provides a gradient-doped white organic electroluminescent device, which comprises, in sequence, a substrate, an anode layer, an anode modification layer, a hole transport layer, a first blue light-emitting layer, an orange-red light-emitting layer, a second blue light-emitting layer, an electron transport layer / hole blocking layer, a cathode modification layer and a metal cathode layer; the first blue light-emitting layer is an organic mixed material in which a blue organic light-emitting material and an organic host material are mixed at a weight ratio of 8.0% to 14.0%; the orange-red light-emitting layer is an organic mixed material in which an organic sensitizing material, an orange-red organic light-emitting material and an organic host material are mixed at a weight ratio of 0.1% to 1.0% and 3.0% to 7.0%, respectively, and the doping concentration gradient of the organic sensitizing material is 0.1% to 0.3%; and the second blue light-emitting layer is an organic mixed material in which a blue organic light-emitting material and an organic host material are mixed at a weight ratio of 12.0% to 18.0%.

[0047] For the conventional gradient-doping technology, although the improvement of a certain performance index (color stability or efficiency) of the white organic electroluminescent device can be achieved, the improvement of the comprehensive performance of the white organic electroluminescent device is difficult to achieve at the expense of other performance indexes (brightness or stability). In the present application, by selecting a rare earth complex having energy level matching as a sensitizing material and gradient-doping into the light-emitting layer, the distribution of the charge carriers can be changed by precise regulation of the distribution of the charge carriers, thereby improving the light-emitting quality of the white organic electroluminescent device, inhibiting the color change of the device and improving the color stability thereof; on the other hand, by regulating the charge carrier balance, the brightness and light-emitting efficiency of the device can be improved, and the efficiency decay of the device can be delayed; in addition, the forward built-in electric field formed by the gradient-doping can reduce the working voltage of the device, greatly reduce the power consumption of the device and improve the working life of the device. By using the gradient-doping method provided by the present application, the comprehensive performance of the white organic electroluminescent device can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 A structure schematic diagram of the white organic electroluminescent device provided by the present application; 1 - glass substrate, 2 - anode layer, 3 - hole injection layer, 4 - hole transport layer, 5 - blue light-emitting layer, 6 - orange-red light-emitting layer, 7 - blue light-emitting layer, 8 - electron transport layer / hole blocking layer, 9 - buffer layer, 10 - metal cathode;

[0049] Figure 2 A voltage-current density-brightness characteristic curve of the white organic electroluminescent device prepared in Example 1;

[0050] Figure 3 A current efficiency-current density-power efficiency characteristic curve of the white organic electroluminescent device prepared in Example 1;

[0051] Figure 4 The spectral diagram of the white organic electroluminescent device prepared in Example 1 at luminance of 1000 cd / m 2 , 2000 cd / m 2 , 5000 cd / m 2 , 10000 cd / m 2 and 20000 cd / m 2 . DETAILED DESCRIPTION

[0052] In order to further illustrate the present application, the gradient-doped white organic electroluminescent device and its preparation method provided by the present application are described in detail below in conjunction with examples.

[0053] Example 1

[0054] The ITO glass with patterned ITO was cleaned with cleaning solution and deionized water for 15 minutes in an ultrasonic cleaner and then dried in an oven. The dried substrate was then transferred into a pretreatment vacuum chamber and then into an organic evaporation chamber. In the organic evaporation chamber with a vacuum degree less than 1.0 x 10 -5 -5 Pa, an 8-nanometer-thick HAT-CN anode modification layer 3, a 60-nanometer-thick TAPC hole transport layer 4, a 4-nanometer-thick FIrpic and TCTA-doped blue light-emitting layer 5, a 6-nanometer-thick Eu(TTA)3phen and Ir(phq)2tpy co-doped TCTA orange light-emitting layer 6, a 10-nanometer-thick FIrpic and CzSi-doped blue light-emitting layer 7 and a 60-nanometer-thick Tm3PyP26PyB electron transport layer / hole blocking layer 8 were sequentially evaporated on the ITO layer. Next, the unfinished device was transferred into a metal evaporation chamber, and a 100-nanometer-thick LiF / Al cathode 9 was evaporated on the electron transport layer / hole blocking layer 8. The vacuum degree was less than 1.0 x 10 -6A white organic electroluminescent device with the structure of ITO / HAT-CN / TAPC / FIrpic(12%):TCTA / Eu(TTA)3phen(0.2%):Ir(phq)2tpy(5%):TCTA / Eu(TTA)3phen(0.4%):Ir(phq)2tpy(5%):TCTA / Eu(TTA)3phen(0.6%):Ir(phq)2tpy(5%):TCTA / FIrpic(16%):CzSi / Tm3PyP26PyB / LiF / Al was prepared by evaporating 0.7 nm thick LiF cathode modification layer under vacuum atmosphere, and finally evaporating 100 nm thick metal Al electrode layer on the LiF layer through a specially designed mask. The evaporation rate of HAT-CN in the anode modification layer 3 was controlled at 0.01 nm / s, the evaporation rate of TAPC in the hole transport layer 4 was controlled at 0.05 nm / s, the evaporation rates of FIrpic and TCTA in the blue light-emitting layer 5 were controlled at 0.006 nm / s and 0.05 nm / s respectively, the evaporation rates of Eu(TTA)3phen in the orange light-emitting layer 6 were controlled at 0.0001 nm / s, 0.0002 nm / s and 0.0003 nm / s respectively, the evaporation rates of Ir(phq)2tpy and TCTA were controlled at 0.0025 nm / s and 0.05 nm / s respectively, the evaporation rates of FIrpic and TCTA in the blue light-emitting layer 7 were controlled at 0.008 nm / s and 0.05 nm / s respectively, the evaporation rate of Tm3PyP26PyB in the electron transport layer / hole blocking layer was controlled at 0.05 nm / s, the evaporation rate of LiF in the cathode modification layer was controlled at 0.005 nm / s, and the evaporation rate of Al in the metal cathode layer was controlled at 0.5 nm / s.

[0055] Figure 2 is the voltage-current density-luminance characteristic curve of the above device. It can be seen that the luminance of the device increases with the increase of current density and driving voltage, and the turn-on voltage of the device is 2.3 volts. The device obtains the maximum luminance of 67384 candela per square meter (cd / m 2 ).

[0056] Figure 3 is the current efficiency-current density-power efficiency characteristic curve of the above device. It can be seen that the maximum current efficiency of the device is 65.27 candela per ampere (cd / A), and the maximum power efficiency is 73.24 lumens per watt (lm / W).

[0057] Figure 4 is the current efficiency-current density-power efficiency characteristic curve of the above device. It can be seen that the maximum current efficiency of the device is 65.27 candela per ampere (cd / A), and the maximum power efficiency is 73.24 lumens per watt (lm / W). 2 , 2000 cd / m 2 , 5000 cd / m 210000cd / m 2 and 20000cd / m 2 The spectrum of the device is shown, with two main emission peaks located at 474 and 611 nm, respectively, and the color coordinates of the device are (0.312, 0.353), (0.311, 0.353), (0.310, 0.352), (0.309, 0.352) and (0.307, 0.351).

[0058] It can be seen that the color coordinates of the device remain almost unchanged as the operating voltage changes.

[0059] Example 2

[0060] First, the patterned ITO glass is ultrasonically cleaned with cleaning solution and deionized water for 15 minutes each, and then dried in an oven. Next, the dried substrate is placed in a pretreatment vacuum chamber, and then transferred to an organic evaporation chamber. The vacuum level is less than 1.0 × 10⁻⁶. -5 In the organic vapor deposition chamber of the device, an 8 nm thick HAT-CN anode modification layer 3, a 60 nm thick TAPC hole transport layer 4, a 4 nm thick blue emitting layer doped with FIrpic and TCTA 5, a 6 nm thick orange-red emitting layer co-doped with Eu(TTA)3phen and Ir(phq)2tpy TCTA 6, a 10 nm thick blue emitting layer doped with FIrpic and CzSi 7, and a 60 nm thick Tm3PyP26PyB electron transport / hole blocking layer 8 were sequentially deposited on the ITO layer. Next, the unfinished device was transferred to a metal vapor deposition chamber, where the deposition temperature was less than 1.0 × 10⁻⁶. -6A white organic electroluminescent device with the structure of ITO / HAT-CN / TAPC / FIrpic(12%):TCTA / Eu(TTA)3phen(0.4%):Ir(phq)2tpy(5%):TCTA / Eu(TTA)3phen(0.6%):Ir(phq)2tpy(5%):TCTA / Eu(TTA)3phen(0.8%):Ir(phq)2tpy(5%):TCTA / FIrpic(16%):CzSi / Tm3PyP26PyB / LiF / Al was prepared by evaporating 0.7 nm thick LiF cathode modification layer under vacuum atmosphere, and finally evaporating 100 nm thick metal Al electrode layer on the LiF layer through a specially designed mask. The evaporation rate of HAT-CN in the anode modification layer 3 was controlled at 0.01 nm / s, the evaporation rate of TAPC in the hole transport layer 4 was controlled at 0.05 nm / s, the evaporation rate of FIrpic and TCTA in the blue light emitting layer 5 was controlled at 0.006 nm / s and 0.05 nm / s respectively, the evaporation rate of Eu(TTA)3phen in the orange light emitting layer 6 was controlled at 0.0002 nm / s, 0.0003 nm / s and 0.0004 nm / s respectively, the evaporation rate of Ir(phq)2tpy and TCTA was controlled at 0.0025 nm / s and 0.05 nm / s respectively, the evaporation rate of FIrpic and TCTA in the blue light emitting layer 7 was controlled at 0.008 nm / s and 0.05 nm / s respectively, the evaporation rate of Tm3PyP26PyB in the electron transport layer / hole blocking layer was controlled at 0.05 nm / s, the evaporation rate of LiF in the cathode modification layer was controlled at 0.005 nm / s, and the evaporation rate of Al in the metal cathode layer was controlled at 0.5 nm / s.

[0061] The obtained device emits white light with two main peaks at about 474 nm and 611 nm under direct current voltage driving. When the luminance is 1000 cd / m 2 , the color coordinates of the device are (0.456, 0.363); the color coordinates of the device hardly change with the change of operating voltage. The luminance of the device is 52851 cd / m 2 . The maximum current efficiency of the device is 49.79 cd / A, and the maximum power efficiency is 54.26 lm / W.

[0062] Example 3

[0063] The patterned ITO glass was first cleaned with cleaning solution and deionized water for 15 minutes under ultrasonic wave and then dried in an oven. Then the dried substrate was transferred into a pre-treatment vacuum chamber and then into an organic evaporation chamber. The vacuum degree was less than 1.0 x 10 -5The HAT-CN anode modification layer 3, the TAPC hole transport layer 4, the blue light emitting layer 5 doped with FIrpic and TCTA, the orange-red light emitting layer 6 co-doped with Eu(TTA)3phen, Ir(phq)2tpy and TCTA, the blue light emitting layer 7 doped with FIrpic and CzSi, and the electron transport layer / hole blocking layer 8 of Tm3PyP26PyB were sequentially deposited on the ITO layer in the organic evaporation chamber of the Pa's machine. Next, the unfinished device was transferred to the metal evaporation chamber, and a 0.7 nm thick LiF cathode modification layer was evaporated under vacuum atmosphere of the Pa's machine. Finally, a 100 nm thick metal Al electrode layer was evaporated on the LiF layer through a specially designed mask, and a white organic electroluminescent device with the structure of ITO / HAT-CN / TAPC / FIrpic(12%):TCTA / Eu(TTA)3phen(0.4%):Ir(phq)2tpy(5%):TCTA / FIrpic(16%):CzSi / Tm3PyP26PyB / LiF / Al was prepared. The evaporation rate of HAT-CN in the anode modification layer 3 was controlled at 0.01 nm / s, the evaporation rate of TAPC in the hole transport layer 4 was controlled at 0.05 nm / s, the evaporation rates of FIrpic and TCTA in the blue light emitting layer 5 were controlled at 0.006 nm / s and 0.05 nm / s respectively, the evaporation rates of Eu(TTA)3phen, Ir(phq)2tpy and TCTA in the orange-red light emitting layer 6 were controlled at 0.0002 nm / s, 0.0025 nm / s and 0.05 nm / s respectively, the evaporation rates of FIrpic and TCTA in the blue light emitting layer 7 were controlled at 0.008 nm / s and 0.05 nm / s respectively, the evaporation rate of Tm3PyP26PyB in the electron transport layer / hole blocking layer was controlled at 0.05 nm / s, the evaporation rate of LiF in the cathode modification layer was controlled at 0.005 nm / s, and the evaporation rate of Al in the metal cathode layer was controlled at 0.5 nm / s. -6 The HAT-CN anode modification layer 3, the TAPC hole transport layer 4, the blue light emitting layer 5 doped with FIrpic and TCTA, the orange-red light emitting layer 6 co-doped with Eu(TTA)3phen, Ir(phq)2tpy and TCTA, the blue light emitting layer 7 doped with FIrpic and CzSi, and the electron transport layer / hole blocking layer 8 of Tm3PyP26PyB were sequentially deposited on the ITO layer in the organic evaporation chamber of the Pa's machine. Next, the unfinished device was transferred to the metal evaporation chamber, and a 0.7 nm thick LiF cathode modification layer was evaporated under vacuum atmosphere of the Pa's machine. Finally, a 100 nm thick metal Al electrode layer was evaporated on the LiF layer through a specially designed mask, and a white organic electroluminescent device with the structure of ITO / HAT-CN / TAPC / FIrpic(12%):TCTA / Eu(TTA)3phen(0.4%):Ir(phq)2tpy(5%):TCTA / FIrpic(16%):CzSi / Tm3PyP26PyB / LiF / Al was prepared. The evaporation rate of HAT-CN in the anode modification layer 3 was controlled at 0.01 nm / s, the evaporation rate of TAPC in the hole transport layer 4 was controlled at 0.05 nm / s, the evaporation rates of FIrpic and TCTA in the blue light emitting layer 5 were controlled at 0.006 nm / s and 0.05 nm / s respectively, the evaporation rates of Eu(TTA)3phen, Ir(phq)2tpy and TCTA in the orange-red light emitting layer 6 were controlled at 0.0002 nm / s, 0.0025 nm / s and 0.05 nm / s respectively, the evaporation rates of FIrpic and TCTA in the blue light emitting layer 7 were controlled at 0.008 nm / s and 0.05 nm / s respectively, the evaporation rate of Tm3PyP26PyB in the electron transport layer / hole blocking layer was controlled at 0.05 nm / s, the evaporation rate of LiF in the cathode modification layer was controlled at 0.005 nm / s, and the evaporation rate of Al in the metal cathode layer was controlled at 0.5 nm / s.

[0064] The obtained device emitted white light with two main peaks at about 474 nm and 611 nm under direct current voltage driving. When the luminance was 1000 cd / m 2 , the color coordinates of the device were (0.380, 0.354); the color coordinates of the device hardly changed with the change of operating voltage. The turn-on voltage of the device was 2.9 volts, and the maximum luminance of the device was 60278 cd / m 2 . The maximum current efficiency of the device was 58.41 cd / A, and the maximum power efficiency of the device was 65.52 lm / W.

[0065] The above description of the embodiments is only used to help understand the method of the present application and its core idea. It should be noted that, for those skilled in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A gradient-doped white organic electroluminescent device, characterized by, The substrate, the anode layer, the anode modification layer, the hole transport layer, the first blue light-emitting layer, the orange-red light-emitting layer, the second blue light-emitting layer, the electron transport layer / hole blocking layer, the cathode modification layer and the metal cathode layer are sequentially compounded. The first blue light-emitting layer is an organic mixed material mixed with a blue organic light-emitting material and an organic host material at a weight ratio of 8.0%-14.0%. The orange-red light-emitting layer is an organic mixed material mixed with an organic sensitizing material, an orange-red organic light-emitting material and an organic host material at a weight ratio of 0.1%-1.0%, 3.0%-7.0% respectively, and the doping concentration gradient of the organic sensitizing material is 0.1%-0.3%. The second blue light-emitting layer is an organic mixed material mixed with a blue organic light-emitting material and an organic host material at a weight ratio of 12.0%-18.0%. In the first blue light-emitting layer, the doped blue organic light-emitting material is one or more of bis(4,6-difluorophenylpyridine-N,C2)picolinato iridium and bis[2-(5-cyano-4,6-difluorophenyl)pyridine-C2,N)] picolinato iridium. The doped organic host material is one or more of 4,4',4"-tris(carbazol-9-yl)triphenylamine and 9,9'-(5-(triphenylsilyl)-1,3-phenyl)di-9H-carbazole. The doped organic sensitizing material in the orange-red light-emitting layer is one or more of tris(thiophenecarboxylic trifluoroacetone)phenanthroline europium and tris(acetylacetone)phenanthroline terbium. The doped orange-red organic light-emitting material is one or more of bis(2-phenylquinoline)(2-(3-methylphenyl)pyridine acid)iridium(III) and bis(2-(9,9-diethyl-fluorene-2-yl)-1-phenyl-1H-benzo[d]imidazole)acetylacetone iridium. The doped organic host material is one or more of 4,4',4"-tris(carbazol-9-yl)triphenylamine and 1,3-biscarbazol-9-ylbenzene. In the second blue light-emitting layer, the doped blue organic light-emitting material is one or more of bis(4,6-difluorophenylpyridine-N,C2)picolinato iridium and bis[2-(5-cyano-4,6-difluorophenyl)pyridine-C2,N)] picolinato iridium. The doped organic host material is one or more of 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole and 2,6-di[3-(9H-9-carbazolyl)phenyl]pyridine.

2. The gradient-doped white organic electroluminescent device according to claim 1, characterized in that The substrate is a glass substrate. The anode layer is indium tin oxide. The cathode modification layer is lithium fluoride. The metal cathode layer is metal aluminum.

3. The gradient-doped white organic electroluminescent device according to claim 1, wherein The anode modification layer is one or more of dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexanitrile, copper (II) phthalocyanine, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane and 7,7,8,8-tetracyanoquinodimethane. The substrate is a glass substrate. The anode layer is indium tin oxide. The cathode modification layer is lithium fluoride. The metal cathode layer is metal aluminum.

4. The gradient-doped white organic electroluminescent device according to claim 1, wherein The hole transport layer is one or more of 4,4'-cyclohexylidenebis[N,N-bis(4-methylphenyl)aniline], tris(4-(quinolin-8-yl)phenyl)amine, N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine.

5. The gradient-doped white organic electroluminescent device according to claim 1, wherein The electron transport layer / hole blocking layer is one or more of 1,3,5-tris(6-(3-(pyridin-3-yl)phenyl)pyridin-2-yl)benzene, 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine, 1,3,5-tris[(3-pyridinyl)-3-phenyl]benzene, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene.

6. The gradient-doped white organic electroluminescent device according to claim 1, wherein The thickness of the anode modification layer is 2 to 10 nanometers; The thickness of the hole transport layer is 30 to 60 nanometers; The thickness of the first blue light-emitting layer is 2 to 6 nanometers; The thickness of the orange light-emitting layer is 4 to 10 nanometers; The thickness of the second blue light-emitting layer is 6 to 12 nanometers; The thickness of the electron transport layer / hole blocking layer is 40 to 80 nanometers; The thickness of the cathode modification layer is 0.6 to 1.5 nanometers; The thickness of the metal cathode layer is 80 to 200 nanometers.

7. A method of manufacturing a gradient-doped white organic electroluminescent device according to any one of claims 1 to 6, comprising the following steps: After the ITO patterned glass substrate was cleaned, the anode modification layer, the hole transport layer, the first blue light emitting layer, the orange red light emitting layer, the second blue light emitting layer and the electron transport layer / hole blocking layer were sequentially evaporated on the ITO anode layer under the condition of a vacuum degree less than 1.0×10 -5 After the ITO patterned glass substrate was cleaned, the anode modification layer, the hole transport layer, the first blue light emitting layer, the orange red light emitting layer, the second blue light emitting layer and the electron transport layer / hole blocking layer were sequentially evaporated on the ITO anode layer under the condition of a vacuum degree less than 1.0×10 Then, the deposition rate was less than 1.0 x 10 -6 The cathode modification layer and the metal cathode layer were sequentially deposited under a vacuum atmosphere of 1.0 x 10

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