CN100586243C - A kind of red organic electroluminescence device and preparation method thereof - Google Patents

Abstract

The invention belongs to a red organic electroluminescent device and a preparation method thereof. Using a vacuum evaporation process, the structure of indium tin oxide/4,4'-bis[N-(p-tolyl)-N-phenyl-amino]diphenyl or N,N'-bis(1 -Naphthyl)-N,N'-diphenyl-1,1'-diphenyl-4,4'-diamine/8-hydroxyquinoline aluminum: trifluoroacetylthiophene acetone and o-phenanthroline as Classical trivalent europium complex Eu(TTA) ₃ phen of first and second ligands: host material 4,4'-N,N'-dicarbazolediphenyl/2,9-dimethyl-4, 7-diphenyl-1,10-phenanthroline/8-hydroxyquinoline aluminum/lithium fluoride/metal aluminum red organic electroluminescent device. The maximum electroluminescent current efficiency of the device is 6.1cd/A, the maximum power efficiency is 3.5lm/W; the maximum brightness is 2451.69cd/m ² .

Description

A kind of red organic electroluminescence device and preparation method thereof

technical field

The invention relates to a red organic electroluminescent device and a preparation method thereof.

Background technique

Compared with other flat display technologies such as liquid crystal displays, plasma display devices, and field emission displays, organic electroluminescent displays have a series of excellent characteristics, such as: adjustable luminous color, active luminescence, high brightness, high efficiency, wide viewing angle, Low energy consumption, simple preparation process, and the ability to prepare curved and flexible display screens have broad application prospects in the field of large flat-panel full-color displays, and are generally considered to be the most competitive next-generation display technology. At present, the performance of green and blue organic electroluminescent devices has been significantly improved, and a small number of products have come out. However, as one of the three essential colors for organic electroluminescent displays, red organic electroluminescent devices still face severe challenges, mainly including low luminous efficiency, rapid decay of efficiency with increasing current density, and low brightness. Therefore, how to design new light-emitting materials and optimize the device structure to obtain high-efficiency, high-brightness red organic electroluminescent devices is one of the research focuses in this field.

In the past ten years, researchers have developed many polymers or organic small molecule red electroluminescent materials, among which rare earth trivalent europium complexes have attracted great attention in the field of organic electroluminescence due to their pure red light and narrow emission spectrum. broad research interests. In order to improve the performance of electroluminescent devices of rare earth trivalent europium complexes, researchers have done a lot of work on the optimization of rare earth trivalent europium complexes and the design of device structures. For example, in 2000, SR Forrest et al. of Princeton University in the United States used 4,4'-N, N'-dicarbazole diphenyl (CBP) as the main material, and TTA and o-phenanthroline (phen) as the first The classic trivalent europium complex Eu(TTA) ₃ phen of the second ligand is doped in CBP as a guest material, and a red electroluminescent device showing the characteristic emission of pure trivalent europium ions is obtained, but the maximum external quantum of the device The efficiency is only 1.4% (0.4mA/cm ² ), which is far below the theoretical limit of 6% for the external quantum efficiency of the device. In 2003, Ma Dongge et al reported on Applied Physics Letters the rare earth europium complex Eu(TTA) ₃ with 3,4,7,8-tetramethyl-o-phenanthroline (Tmphen) as the second ligand Tmphen, as a guest material, was mixed into the host material CBP to make a red organic electroluminescent device. Although the maximum current efficiency reached 4.7cd/A, its maximum brightness was only 800cd/m ² . In 2005, Zhang Hongjie and others published in Inorganic Chemistry that 4,4,5,5,6,6,6-heptafluoro-1-(2-naphthyl)-n-ethane-β-diketone (HFNH) was the first The rare earth europium complex Eu(HFNH) ₃ phen of the ligand was doped into CBP as a guest material to prepare a pure red electroluminescent device, with a maximum current efficiency of 4.14cd/A, but its maximum brightness was only 957cd /m ² . It can be seen that although the method of doping the trivalent europium complex into the wide bandgap host material as the light-emitting layer can better solve the problems of poor color purity and low efficiency of the device, the problems of low brightness and rapid decay of the luminous efficiency of the device Still no substantial improvement.

The main reason for the efficiency decay of trivalent europium complex electroluminescent devices is the long lifetime of excited states of central ions, which leads to severe triplet quenching of devices at high current densities. Moreover, in doped organic electroluminescent devices, many trivalent europium complexes only bind one kind of carrier (electron or hole), and the other kind of carrier is mainly distributed on the host material molecules. In 2007, Zhang Hongjie et al proved experimentally (Journal of Applied Physics): In the Eu(TTA) ₃ phen doped CBP system, Eu(TTA) ₃ phen molecules only bind electrons, while most of the holes are distributed in the CBP molecularly. As the current density increases, the dominant light emission mechanism of the device gradually shifts from carrier trapping to Förster energy transfer. On the other hand, most trivalent europium complexes only absorb light in the ultraviolet region, so it is easy to cause incomplete energy transfer from the host material to the trivalent europium complex, which is obviously not conducive to the improvement of device luminous efficiency and brightness. Therefore, how to solve the above problems by designing new device structures and optimizing the device manufacturing process is an urgent task to improve the performance of trivalent europium complex electroluminescent devices and demonstrate their potential advantages in organic electroluminescent applications.

Contents of the invention

One of the objects of the present invention is to provide a red organic electroluminescent device.

Another object of the present invention is to provide a preparation method for this red organic electroluminescent device.

As shown in accompanying drawing 1, the red organic electroluminescent device provided by the present invention is made up of substrate 1, anode layer 2, hole transport layer 3, light-emitting layer 4, hole blocking layer 5, electron transport layer 6, buffer layer 7 and metal cathode 8 are formed by connecting in sequence;

Substrate 1 is a glass substrate;

The anode layer 2 adopts indium tin oxide (ITO), and the surface resistance of the preferred indium tin oxide layer is 10-25 ohms; more preferably the ITO anode layer processed by low pressure oxygen plasma;

The hole transport layer 3 uses: 4,4'-bis[N-(p-tolyl)-N-phenyl-amino]diphenyl (TPD for short) or N,N'-bis(1-naphthyl) -N, N'-diphenyl-1,1'-diphenyl-4,4'-diamine (abbreviated as NPB); their molecular structures are as follows:

The light-emitting layer 4 adopts: an organic mixed material in which a red organic dye and an organic sensitizing dye are double-doped into the host organic molecular material;

The red organic dye doped therein is: trivalent europium complex Eu(TTA) ₃ phen with trifluoroacetylthiophene acetone (TTA) and o-phenanthroline (phen) as the first and second ligands, its molecular structure as follows:

The doped organic sensitizing dye is: 8-hydroxyquinoline aluminum (referred to as AlQ), and its molecular structure is as follows:

The main organic molecular material is: 4,4'-N,N'-dicarbazole diphenyl (CBP for short), and its molecular structure is as follows:

In the organic mixed material, the weight ratio of the doped red organic dye to the host organic molecular material is 2%-5%, and the weight ratio of the doped organic sensitizing dye to the host organic molecular material is 0.1%-0.6% ;

Hole blocking layer 5 adopts: 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (abbreviated as BCP), its molecular structure is as follows:

The electron transport layer 6 is made of: 8-hydroxyquinoline aluminum (referred to as AlQ);

What buffer layer 7 adopts is lithium fluoride (LiF);

What metal cathode 8 adopts is metallic aluminum (Al);

The anode and the cathode intersect each other to form a light-emitting area of the device, with an area of 10 square millimeters; the thickness of the hole transport layer 3 is 30 to 60 nanometers, the thickness of the light-emitting layer 4 is 30 to 50 nanometers, and the thickness of the hole blocking layer 5 is 30 to 60 nanometers. The thickness is 15 to 30 nanometers, the thickness of the electron transport layer 6 is 20 to 40 nanometers, the thickness of the buffer layer 7 is 0.4 to 1.8 nanometers, and the thickness of the metal cathode 8 is 60 to 120 nanometers.

When a forward voltage is applied between the two electrodes, the device emits red light with a main peak at 612 nanometers.

The preparation method of the red organic electroluminescent device provided by the invention is as follows:

Firstly, the ITO layer 2 on the glass substrate 1 is chemically etched into strip-shaped electrodes, then ultrasonically cleaned with cleaning solution and deionized water for 10-20 minutes, and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer it to the Organic evaporation chamber. When the degree of vacuum reaches 1-5×10 ^-5 Pa, the hole transport layer 3 , the light emitting layer 4 , the hole blocking layer 5 and the electron transport layer 6 are vapor-deposited on the ITO layer 2 in sequence. Next, the unfinished device is transferred to a metal evaporation chamber, and the buffer layer 7 and the metal cathode 8 are sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa.

Wherein, the anode and the cathode intersect each other to form the light-emitting area of the device, with an area of 10 square millimeters; the thickness of the hole transport layer 3 is 30 to 60 nanometers, the thickness of the light-emitting layer 4 is 30 to 50 nanometers, and the thickness of the hole blocking layer 5 15 to 30 nanometers, the thickness of the electron transport layer 6 is 20 to 40 nanometers, the thickness of the buffer layer 7 is 0.4 to 1.8 nanometers, the thickness of the metal cathode 8 is 60 to 120 nanometers; the hole transport layer 3, the light emitting layer 4, The evaporation rate of TPD (or NPB), CBP, BCP and AlQ in hole blocking layer 5 and electron transport layer 6 is controlled at 0.05-0.1 nanometer/second, and the evaporation rate of red organic dye is controlled at 0.001-0.005 nanometer/second, has The evaporation rate of the sensitizing dye is controlled at 0.00005-0.0006 nanometers/second, the evaporation rate of LiF in the buffer layer 7 is controlled at 0.005-0.015 nanometers/second, and the evaporation rate of Al in the metal cathode 8 is controlled at 0.5-1.5 nanometers/second; When plating the luminescent layer 4, the red organic dye, the organic sensitizing dye and the host organic molecular material in the organic mixed material are evaporated simultaneously in different evaporation sources, and the doped red organic dye and the host organic molecule are evaporated by adjusting the evaporation rate of the three materials. The weight ratio of the organic molecular material is controlled between 2% and 5%, and the weight ratio of the organic sensitizing dye and the host material is controlled between 0.1% and 0.6%.

The beneficial effect of the present invention is: by co-doping the organic sensitizing dye AlQ with superior electron transport capacity and the trivalent europium complex into the wide energy gap host material CBP in a specific ratio, the transport of electrons in the light-emitting region can be improved It is beneficial to broaden the luminescence range of the device and weaken the exciton concentration, thereby delaying the decay of the electroluminescent efficiency of the device with the increase of the current density. In addition, the doping of AlQ molecules is beneficial to promote the balanced distribution of electrons and holes on the trivalent europium complex molecules in the light-emitting layer, thereby further improving the efficiency of the device.

Another advantage of the present invention is: by performing precise low-pressure oxygen plasma treatment on the ITO anode, the hole injection capability of the device is greatly improved, and the working voltage of the device is reduced; The injection is conducive to causing an appropriate amount of hole accumulation in the light-emitting region, which is conducive to balancing the distribution of electrons and holes on the trivalent europium complex molecules, thereby improving the carrier recombination probability of the device, and finally improving the electroluminescent efficiency of the device . The maximum electroluminescent current efficiency of the obtained device is 6.1cd/A, the maximum power efficiency is 3.5lm/W, the maximum external quantum efficiency is 3.3%, and the corresponding maximum recombination probability of the device is 54.9%; the maximum brightness of the obtained device is 2451.69cd /m ² .

Description of drawings

Fig. 1 is a schematic structural view of a red organic electroluminescent device provided by the present invention. In the figure, 1 is a glass substrate, 2 is an anode layer, 3 is a hole transport layer, 4 is a light-emitting layer, 5 is a hole blocking layer, 6 is an electron transport layer, 7 is a buffer layer, and 8 is a metal cathode. Fig. 1 is also a drawing of the abstract of the present invention.

Fig. 2 is the voltage-current density-brightness characteristic curve of Example 4 of the red organic electroluminescent device provided by the present invention. The brightness of the device increases with the increase of the current density and the driving voltage. The lighting voltage of the device is 5.4 volts. When the voltage is 17.5 volts and the current density is 464.19 milliamperes per square centimeter (mA/cm ² ), the device obtains The maximum brightness is 2110.2 candela per square meter (cd/m ² ).

Fig. 3 is the current density-power efficiency-current efficiency characteristic curve of Example 4 of the red organic electroluminescent device provided by the present invention. The device has a maximum current efficiency of 6.1 candela per ampere (cd/A) and a maximum power efficiency of 3.5 lumens per watt (1m/W).

Fig. 4 is the voltage-current density-brightness characteristic curve of Example 6 of the red organic electroluminescent device provided by the present invention. The brightness of the device increases with the increase of the current density and driving voltage. The lighting voltage of the device is 5.4 volts. When the voltage is 18.0 volts and the current density is 468.69mA/cm ² , the device obtains the maximum brightness of 2073.8cd/m ² .

Fig. 5 is the current density-power efficiency-current efficiency characteristic curve of Example 6 of the red organic electroluminescent device provided by the present invention. The maximum current efficiency of the device is 5.99cd/A, and the maximum power efficiency is 3.46lm/W.

Fig. 6 is a spectrum diagram of Example 4 of the red organic electroluminescent device provided by the present invention, the spectrum is all derived from the characteristic emission of trivalent europium ions, and the main peak is located at 612 nanometers.

Detailed ways

The present invention will be further described below in conjunction with drawings and embodiments.

Example 1:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.0 nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 100 nanometers is prepared into an organic electroluminescent device with a structure of ITO/TPD/AlQ(0.2%):Eu(TTA) ₃ phen(3%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rates of TPD, CBP, BCP and AlQ (electron transport layer) were controlled at 0.05 nm/s, and the evaporation rates of AlQ and Eu(TTA) ₃ phen in the light-emitting layer were controlled at 0.0001 nm/s and 0.0015 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 5.5 volts, and the maximum brightness of the device is 2035.34 cd/m ² . The maximum current efficiency of the device is 5.25cd/A, and the maximum power efficiency is 3.02lm/W. In addition, the maximum external quantum efficiency of the device is 2.84%, and the corresponding carrier recombination probability is 47.3%.

Example 2:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.0 nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 100 nanometers is prepared into an organic electroluminescent device with a structure of ITO/TPD/AlQ(0.3%):Eu(TTA) ₃ phen(3%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rate of TPD, CBP, BCP and AlQ (electron transport layer) was controlled at 0.05 nm/s, the evaporation rate of AlQ and Eu(TTA) ₃ phen in the light-emitting layer was controlled at 0.00015 nm/s and 0.0015 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 5.3 volts, and the maximum brightness of the device is 2394.58cd/m ² . The maximum current efficiency of the device is 5.60cd/A, and the maximum power efficiency is 3.32lm/W. In addition, the maximum external quantum efficiency of the device is 3.02%, and the corresponding carrier recombination probability is 50.4%.

Example 3:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.0 nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 100 nanometers is prepared into an organic electroluminescent device with a structure of ITO/TPD/AlQ(0.4%):Eu(TTA) ₃ phen(3%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rates of TPD, CBP, BCP and AlQ (electron transport layer) were controlled at 0.05 nm/s, the evaporation rates of AlQ and Eu(TTA) ₃ phen in the light-emitting layer were controlled at 0.0002 nm/s and 0.0015 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 5.3 volts, and the maximum brightness of the device is 2199.09 cd/m ² . The maximum current efficiency of the device is 5.24cd/A, and the maximum power efficiency is 3.05lm/W. In addition, the maximum external quantum efficiency of the device is 2.83%, and the corresponding carrier recombination probability is 47.2%.

Example 4:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.2nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 100 nanometers is prepared into an organic electroluminescent device with a structure of ITO/TPD/AlQ(0.3%):Eu(TTA) ₃ phen(3%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rate of TPD, CBP, BCP and AlQ (electron transport layer) was controlled at 0.05 nm/s, the evaporation rate of AlQ and Eu(TTA) ₃ phen in the light-emitting layer was controlled at 0.00015 nm/s and 0.0015 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 5.4 volts, and the maximum brightness of the device is 2110.23cd/m ² . The maximum current efficiency of the device is 6.1cd/A, and the maximum power efficiency is 3.5lm/W. In addition, the maximum external quantum efficiency of the device is 3.29%, and the corresponding carrier recombination probability is 54.9%.

Example 5:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.2nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 80 nanometers is prepared into an organic electroluminescent device with a structure of ITO/TPD/AlQ(0.3%):Eu(TTA) ₃ phen(3%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rate of TPD, CBP, BCP and AlQ (electron transport layer) was controlled at 0.05 nm/s, the evaporation rate of AlQ and Eu(TTA) ₃ phen in the light-emitting layer was controlled at 0.00015 nm/s and 0.0015 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 5.4 volts, and the maximum brightness of the device is 2122.55 cd/m ² . The maximum current efficiency of the device is 5.45cd/A, and the maximum power efficiency is 3.12lm/W. In addition, the maximum external quantum efficiency of the device is 2.94%, and the corresponding carrier recombination probability is 49.1%.

Embodiment 6:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.0 nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 80 nanometers is prepared into an organic electroluminescent device with a structure of ITO/TPD/AlQ(0.3%):Eu(TTA) ₃ phen(3%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rate of TPD, CBP, BCP and AlQ (electron transport layer) was controlled at 0.05 nm/s, the evaporation rate of AlQ and Eu(TTA) ₃ phen in the light-emitting layer was controlled at 0.00015 nm/s and 0.0015 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device was 5.4 volts, and the maximum brightness of the device was 2073.80 cd/m ² . The maximum current efficiency of the device is 5.99cd/A, and the maximum power efficiency is 3.46lm/W. In addition, the maximum external quantum efficiency of the device is 3.23%, and the corresponding carrier recombination probability is 53.9%.

Embodiment 7:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick NPB hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.2nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 80 nanometers is prepared into an organic electroluminescent device with a structure of ITO/NPB/AlQ(0.3%):Eu(TTA) ₃ phen(3%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rates of NPB, CBP, BCP and AlQ (electron transport layer) were controlled at 0.05 nm/s, the evaporation rates of AlQ and Eu(TTA) ₃ phen in the light-emitting layer were controlled at 0.00015 nm/s and 0.0015 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 6.0 volts, and the maximum brightness of the device is 2006.15 cd/m ² . The maximum current efficiency of the device is 5.71cd/A, and the maximum power efficiency is 3.04lm/W. In addition, the maximum external quantum efficiency of the device is 3.08%, and the corresponding carrier recombination probability is 51.4%.

Embodiment 8:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick NPB hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.2nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 100 nanometers is prepared into an organic electroluminescent device with a structure of ITO/NPB/AlQ(0.3%):Eu(TTA) ₃ phen(3%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rates of NPB, CBP, BCP and AlQ (electron transport layer) were controlled at 0.05 nm/s, the evaporation rates of AlQ and Eu(TTA) ₃ phen in the light-emitting layer were controlled at 0.00015 nm/s and 0.0015 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 5.9 volts, and the maximum brightness of the device is 2002.98cd/m ² . The maximum current efficiency of the device is 5.60cd/A, and the maximum power efficiency is 3.02lm/W. In addition, the maximum external quantum efficiency of the device is 3.02%, and the corresponding carrier recombination probability is 50.4%.

Embodiment 9:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 1.2nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 100 nanometers is prepared into an organic electroluminescent device with a structure of ITO/TPD/AlQ(0.3%):Eu(TTA) ₃ phen(4%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rates of TPD, CBP, BCP and AlQ (electron transport layer) were controlled at 0.05 nm/s, the evaporation rates of AlQ and Eu(TTA) ₃ phen in the light-emitting layer were controlled at 0.00015 nm/s and 0.002 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 5.4 volts, and the maximum brightness of the device is 2451.69 cd/m ² . The maximum current efficiency of the device is 5.98cd/A, and the maximum power efficiency is 3.45lm/W. In addition, the maximum external quantum efficiency of the device is 3.23%, and the corresponding carrier recombination probability is 53.8%.

Example 10:

Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In an organic evaporation chamber with a vacuum of 1-5×10 ^-5 Pa, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) ₃ phen and AlQ co-doped layer were sequentially evaporated on the ITO layer. The light-emitting layer of CBP, the 20 nm thick BCP hole blocking layer and the 30 nm thick AlQ electron transport layer. Next, the unfinished device is transferred to a metal evaporation chamber, and a 0.8 nm thick LiF buffer layer is sequentially evaporated in a vacuum atmosphere of 5-8×10 ^-5 Pa, and finally evaporated on LiF through a special mask A metal Al electrode with a thickness of 100 nanometers is prepared into an organic electroluminescent device with a structure of ITO/TPD/AlQ(0.3%):Eu(TTA) ₃ phen(4%):CBP/BCP/AlQ/LiF/Al. The device has a light-emitting area of 10 square millimeters. The evaporation rates of TPD, CBP, BCP and AlQ (electron transport layer) were controlled at 0.05 nm/s, the evaporation rates of AlQ and Eu(TTA) ₃ phen in the light-emitting layer were controlled at 0.00015 nm/s and 0.002 nm/s, and LiF The evaporation rate is controlled at 0.005 nm/s, and the evaporation rate of Al is controlled at 0.5 nm/s. The obtained device shows red luminescence of Eu(TTA) ₃ phen under the driving of DC voltage, and the main peak is located at 612 nanometers. The lighting voltage of the device is 5.4 volts, and the maximum brightness of the device is 1995.05 cd/m ² . The maximum current efficiency of the device is 5.93cd/A, and the maximum power efficiency is 3.46lm/W. In addition, the maximum external quantum efficiency of the device is 3.20%, and the corresponding carrier recombination probability is 53.4%.

Claims (6)

1, a kind of red organic electroluminescence device is by substrate (1), anode layer (2), hole transmission layer (3), luminescent layer (4), hole blocking layer (5), electron transfer layer (6), resilient coating (7) and metallic cathode (8), by connecting and composing in turn; Described substrate (1) is a glass substrate; Anode layer (2) adopts: indium tin oxide; Resilient coating (7) adopts: lithium fluoride; Metallic cathode (8) adopts: metallic aluminium; It is characterized in that:

Described hole transmission layer (3) adopts: 4,4 '-two [N-(right-tolyl)-N-phenyl-amino] diphenyl or N, N '-two (1-naphthyl)-N, N '-diphenyl-1,1 '-diphenyl-4,4 '-diamines; Their molecular structure is as follows:

Described luminescent layer (4) adopts: the organic mixed material of main body organic molecule material is gone in red organic dyestuff and organic sensitizing dyestuff codope; Wherein the red organic dyestuff of Can Zaing is to be the trivalent europium complex Eu (TTA) of first and second parts with trifluoroacetyl thiophene acetone and Phen ₃Phen, its molecular structure is as follows:

Organic sensitizing dyestuff of described doping is an oxine aluminium, and its molecular structure is as follows:

Described main body organic molecule material is 4,4 '-N, and N '-two carbazole diphenyl, its molecular structure is as follows:

In the described organic mixed material, the red organic dyestuff of doping and the weight ratio of main body organic molecule material are 2%-5%, and the organic sensitizing dyestuff of doping and the weight ratio of main body organic molecule material are 0.1%-0.6%;

Described hole blocking layer (5) adopts: 2, and 9-dimethyl-4,7-diphenyl-1, the 10-phenanthroline, its molecular structure is as follows:

Described electron transfer layer (6) adopts: oxine aluminium.

2, a kind of red organic electroluminescence device as claimed in claim 1 is characterized in that the face resistance of the indium tin oxide layer of described anode layer (2) is 10-25 ohm.

3, a kind of red organic electroluminescence device as claimed in claim 1 or 2, the indium tin oxide layer that it is characterized in that described anode layer (2) is what handled by the Low Pressure Oxygen plasma.

4, a kind of red organic electroluminescence device as claimed in claim 1 or 2 is characterized in that described anode layer (2) and metallic cathode (8) intersect to form the luminous zone of device mutually, and area is 10 square millimeters; The thickness of hole transmission layer (3) is 30 to 60 nanometers, the thickness of luminescent layer (4) is 30 to 50 nanometers, the thickness of hole blocking layer (5) is 15 to 30 nanometers, the thickness of electron transfer layer (6) is 20 to 40 nanometers, the thickness of resilient coating (7) is 0.4 to 1.8 nanometer, and the thickness of metallic cathode (8) is 60 to 120 nanometers.

5, a kind of red organic electroluminescence device as claimed in claim 3 is characterized in that described anode layer (2) and metallic cathode (8) intersect to form the luminous zone of device mutually, and area is 10 square millimeters; The thickness of hole transmission layer (3) is 30 to 60 nanometers, the thickness of luminescent layer (4) is 30 to 50 nanometers, the thickness of hole blocking layer (5) is 15 to 30 nanometers, the thickness of electron transfer layer (6) is 20 to 40 nanometers, the thickness of resilient coating (7) is 0.4 to 1.8 nanometer, and the thickness of metallic cathode (8) is 60 to 120 nanometers.

6, the preparation method of a kind of red organic electroluminescence device as claimed in claim 1, it is characterized in that step is as follows with condition: the electrode that earlier ITO layer (2) chemical corrosion on the ito glass substrate (1) is become fine strip shape, use cleaning fluid then successively, deionized water ultrasonic cleaning 10-20 minute is also put into oven for drying, then dried substrate is put into the preliminary treatment vacuum chamber, be with the voltage of 200-350 volt it to be carried out after 5-15 minute the Low Pressure Oxygen plasma treatment it being transferred to the organic vapor deposition chamber under the atmosphere of 8-15 handkerchief in vacuum degree, treat that vacuum degree reaches 1-5 * 10 ^-5During handkerchief, go up evaporation hole transmission layer (3), luminescent layer (4), hole blocking layer (5) and electron transfer layer (6) at ITO layer (2) successively, next, uncompleted device is transferred to the metal evaporation chamber, in 5-8 * 10 ^-5Evaporation resilient coating (7) and metallic cathode (8) successively under the vacuum of handkerchief;

In hole transmission layer (3), luminescent layer (4), the hole blocking layer (5) 4,4 '-two [N-(right-tolyl)-N-phenyl-amino] diphenyl, 4,4 '-N, N '-two carbazole diphenyl, 2,9-dimethyl-4,7-diphenyl-1, the evaporation rate of the oxine aluminium of 10-phenanthroline and electron transfer layer (6) is controlled at the 0.05-0.1 nm/sec, is the trivalent europium complex Eu (TTA) of first and second parts with trifluoroacetyl thiophene acetone and Phen in the luminescent layer (4) ₃The evaporation rate of phen is controlled at the 0.001-0.005 nm/sec, the evaporation rate of organic sensitizing dyestuff oxine aluminium is controlled at the 0.00005-0.0006 nm/sec, the evaporation rate of lithium fluoride is controlled at the 0.005-0.015 nm/sec in the resilient coating (7), and the evaporation rate of metallic aluminium is controlled at the 0.5-1.5 nm/sec in the metallic cathode (8); During evaporation luminescent layer (4), organic dyestuff, organic sensitizing dyestuff and the main body organic molecule material that organic mixed material mixes be evaporation simultaneously in different evaporation sources, make the red organic dyestuff of doping and the weight ratio of main body organic molecule material be controlled between the 2%-5% by the evaporation rate of regulating and control three kinds of materials, the weight ratio of organic sensitizing dyestuff and main body organic molecule material is controlled between the 0.1%-0.6%.

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