CN1161002C - An organic electroluminescent device - Google Patents

Abstract

The invention relates to an organic electroluminescent device. The hole transport layer (4) of the device adopts an organic quantum well structure. This quantum well transport structure is composed of two material layers alternately overlapping, an organic material A with a wide energy band and an organic material B with a narrow energy band. The two organic materials The energy levels of the materials match each other (that is, the energy band of material A can realize the wrapping of the energy band of material B), and a potential barrier of holes is formed at the interface of the quantum well. The organic quantum well structure adopted in the hole transport layer of the present invention can significantly control the migration of hole carriers in the hole transport layer, and realize the injection balance of electrons and holes in the light-emitting region, thereby improving the luminous efficiency and efficiency of the device. Luminous brightness. If the organic material B that forms the organic quantum well structure is dye C, the device has different luminescent centers with the organic quantum well period number in the hole transport layer, that is, it can be controlled by the organic quantum hydrazine period number in the hole transport layer. Change the recombination light-emitting area of electrons and holes in the device, and then adjust the light-emitting center of the device.

Description

An organic electroluminescent device

technical field

The invention relates to an organic electroluminescent device, more specifically, the invention relates to an organic electroluminescent device with high luminous efficiency and high luminous brightness, and also relates to an organic electroluminescent device with adjustable luminescent center.

Background technique

Today, with the development of multimedia technology and the advent of the information society, the requirements for the performance of flat panel displays are getting higher and higher. In recent years, three new display technologies: plasma display, field emission display and organic electroluminescent display have made up for the shortcomings of cathode ray tubes and liquid crystal displays to a certain extent. Among them, organic electroluminescent displays have a series of advantages such as self-illumination, low-voltage DC drive, full curing, wide viewing angle, and rich colors. Low, its response speed can reach 1000 times that of liquid crystal display, but its manufacturing cost is lower than the liquid crystal display of the same resolution, therefore, organic electroluminescent display has broad application prospects.

In 1987, CWTANG et al. (CWTang, SASlyke, Appl. Phys. Lett.51, 913 (1987)) of Kodak Company in the United States adopted a double-layer structure for the first time, using aromatic diamine derivatives as hole transport materials, and using a The organic small molecule material with high fluorescence efficiency and can be made into uniform and dense high-quality thin film by vacuum coating method——Alq ₃ is used as the light-emitting layer material to prepare higher quantum efficiency (1%) and high luminous efficiency (>1.51m/ W), high brightness (>1000cd/m ² ) and low driving voltage (<10V) organic electroluminescent devices (Organic Electroluminescent Devices, hereinafter referred to as OLEDs), making the research work in this field enter a new era. In 1990, Burroughes and his colleagues at the Cavendish Laboratory of Cambridge University in the United Kingdom discovered that polymer materials also have good electroluminescent properties. This important discovery extended the research on organic electroluminescent materials to the polymer field. For more than ten years, people have continuously improved the preparation process of organic electroluminescent devices, and its related technologies have developed rapidly.

The internal quantum efficiency of OLEDs mainly depends on the carrier injection, transport, and recombination efficiency, and the luminous efficiency of the device is also strongly affected by the balance of electron and hole injection. In traditional NPB/Alq ₃ bilayer devices, the hole transport ability of NPB is much greater than that of Alq ₃ for electrons, thus leading to a serious imbalance in carrier transport in the device, thereby reducing the luminescence of the device. efficiency. It has been found that using a suitable hole transport material or using a suitable device structure to match the electron transport material (such as Alq ₃ ) in the device is an effective way to improve the performance of the device. The first scheme is to use the way of doping to add rubrene material in the hole transport layer, Y.Hamada and MSJang et al. (Y.Hamada, T.Sano, K.Shibata, and K.Kuroki, Jpn.J.Appl. Phys., Part 234, L824 (1995); MS Jang, SYSong, HK Shim, T. Zyung, SD Jung, LMDo, Synth. Met.91, 317 (1997)) have all carried out similar research work. Aziz et al. (H.Aziz, Z.Popovic, NXHu, AMHor, and G.Xu, Science 283, 1900 (1999); H.Azizand ZD Popovic, Appl. Phys. Lett. 80, 2180 (2002)) think its role The mechanism is that by doping the rubrene material, the doped rubrene molecules act as hole traps, thereby improving the performance of the device. Another approach is to use quantum well structures to improve device efficiency. The organic quantum well structure has achieved some success in helping to reduce the emission spectrum width of OLEDs, improve the luminous efficiency of the device, and convert the luminous color of the device. However, in the current research, the organic quantum well structure is generally used to increase the concentration of electrons and holes in the light-emitting layer, thereby improving the recombination efficiency of carriers. For example, N.Tada et al. (N.Tada, S.Tatsuhara, A.Fujii, Y.Ohmori and K.Yoshino, Jpn.J.Appl.Phys.36, 421 (1997)) use Alq in the light-emitting layer of OLEDs ₃ and TPD alternating multi-layer quantum well structure, the luminous efficiency of the device is improved compared with the traditional structure (only Alq ₃ is used in the light-emitting layer). Similar experiments further confirmed that this performance improvement is mainly due to the increase in the carrier concentration of the light-emitting layer. However, the use of an organic quantum well structure in the light-emitting layer only increases the concentration of carriers in the light-emitting layer, and the injection balance of electrons and holes cannot be achieved in the light-emitting region, and excessive holes will still lead to a decrease in luminous efficiency. Therefore, the ability of the light-emitting layer to improve the carrier recombination efficiency by adopting this structure is relatively limited.

Contents of the invention

The object of the present invention is to provide an organic electroluminescent device with high luminous efficiency and high luminous brightness.

Another object of the present invention is to provide an organic electroluminescent device with adjustable luminescent center.

To achieve the above object, the technical solution of the present invention is to provide an organic electroluminescent device, which comprises a transparent substrate, a first electrode layer and a second electrode layer, and The hole transport layer and the electron transport layer between the layers are characterized in that: the hole transport layer adopts an organic quantum well structure, and this quantum well transport structure is composed of an organic material A with a wide energy band and an organic material B with a narrow energy band. The material layers are alternately overlapped with a certain number of periods, and the energy levels of the two organic materials satisfy the following relationship:

(1) The highest occupied orbital energy level of organic material A is lower than the highest occupied orbital energy level of organic material B (hereinafter referred to as HOMO energy level),

(II) The lowest unoccupied orbital energy level of the organic material A is higher than the lowest unoccupied orbital energy level of the organic material B (hereinafter referred to as LUMO energy level), wherein the period number of the organic quantum well structure is an integer ranging from 1 to 10.

The energy levels of the two organic materials used in the hole transport layer in the above-mentioned technical solution match each other (satisfy the above-mentioned relational formulas (I) and (II) at the same time), that is, in the organic quantum well structure, the energy band of material A can realize Band wrapping to material B. Since the carriers at the interface tend to move to lower energy positions, at the interface between the material A layer and the B layer, both holes and electrons tend to move to the material B layer, that is, the energy of the material A layer to the material B layer The level potential barrier effect makes the potential wells of both electrons and holes in the material B layer. When holes are transported through the organic quantum well structure, a large number of hole carriers are distributed in the material B layer, but the probability of distribution in the material A layer is very small, and the material A layer can only be transported by tunneling. There is a potential barrier of holes at the interface between the material B layer and the material A layer, and holes need to overcome the potential barrier to lose energy when tunneling through the A layer. Therefore, it can be concluded that: (1) The larger the energy level barrier of the interface, the more energy the hole carriers need to consume to cross the interface, so more carriers are bound in the material B layer due to insufficient energy , cannot pass through the entire quantum well structure; (2) With the increase of the period number of quantum wells, the interfaces that carriers need to pass through through the quantum wells will increase, which will also reduce the number of holes passing through the entire quantum well structure. to block holes. Therefore, the choice of the material and its period number that make up the quantum well structure can well control the migration of hole carriers in the hole transport layer, and realize the injection balance of electrons and holes in the light-emitting region, thereby improving the light emission of the device. efficiency and luminous brightness.

The organic material B described in the technical solution of the present invention may be a dye C.

Studies have shown that: in the quantum well transport layer structure, (1) the greater the energy level barrier of the interface, the more energy is consumed for carriers to cross the interface, so more carriers are bound in the quantum well due to insufficient energy. In the material C layer, it cannot pass through the entire quantum well structure; (2) With the increase of the period number, the interfaces that carriers need to pass through the quantum well transmission will increase, which will also reduce the number of carriers passing through the quantum well structure , play the role of blocking carriers. Therefore, when the electron and hole barriers at the quantum well interface are small (<0.4eV), most of the holes can be trapped in the quantum well structure, and a small part of the holes can be further transported across the quantum well. At the same time, after the electrons recombine with a small part of the holes transported here in the electron transport layer, the remaining electrons can also cross the small quantum well barrier and transport into the hole transport layer of the quantum well structure, which is bound in the quantum well structure. The holes in the well are further recombined, so that the two luminescent centers emit light simultaneously. By adjusting the period number of the organic quantum well structure, the luminescent center can be made to exist in the electron transport layer (at this time, the period number is small, and most of the holes pass through the quantum well structure to emit the EL spectrum of the electron transport layer material) or the hole transport layer ( At this time, the number of cycles is large, the holes are completely bound in the quantum well structure, and the electrons in the electron transport layer are introduced into the quantum well structure and recombined with the holes, emitting the EL spectrum of the organic dye C), or exist in both the electron transport layer and the hole transport layer. Then, the device has different luminescent centers with different organic quantum well periods in the hole transport layer, that is to say, the recombination of electrons and holes in the device can be changed by controlling the organic quantum well period in the hole transport layer. The light-emitting area, and then adjust the light-emitting center of the device.

In the technical solution of the present invention, a buffer layer may be sandwiched between the first electrode layer and the hole transport layer, and a transition layer may be sandwiched between the hole transport layer and the electron transport layer.

The organic electroluminescent device proposed by the present invention has the following advantages:

①The organic quantum well structure used in the hole transport layer can significantly control the migration of hole carriers in the hole transport layer, thereby realizing the injection balance of electrons and holes in the light-emitting region, thereby improving the luminous efficiency and Luminous brightness;

②If the organic material B with a narrow energy band constituting the organic quantum well structure is a dye C, the device will have different luminescent centers depending on the number of periods of the organic quantum well in the hole transport layer, that is to say, it can be controlled by controlling the organic quantum well in the hole transport layer. The period number of the organic quantum well can be used to change the recombination light-emitting area of electrons and holes in the device, and then adjust the light-emitting center of the device.

Description of drawings

The present invention will become clearer by describing the specific implementation modes and examples below in conjunction with the accompanying drawings.

Fig. 1 is the structural representation of the organic electroluminescent device that the present invention proposes (comprising dispensable buffer layer and transition layer in the device structure of schematic diagram), wherein 1 is transparent substrate, and 2 is the first electrode layer (anode layer ), 3 is a buffer layer, 4 is a hole transport layer (with an organic quantum well structure), 5 is a transition layer, 6 is an electron transport layer, 7 is a second electrode layer (cathode layer), and 8 is a power supply.

Fig. 2 and Fig. 3 are schematic diagrams of energy levels of OLEDs with a device structure proposed by the present invention such as structural formula (1), and Fig. 3 also shows the distribution of carriers in the organic quantum well structure.

Fig. 4 is the luminance-current density curves of OLEDs with different period numbers n proposed by the present invention (device structure is shown in structural formula (1)).

Fig. 5 is a luminous efficiency-current density curve of OLEDs with different period numbers n proposed by the present invention (device structure is shown in structural formula (1)).

Fig. 6 is a schematic diagram of energy levels of OLEDs with a device structure proposed by the present invention, such as structural formula (2).

Fig. 7 is the luminance-current density curves of OLEDs with different period numbers n proposed by the present invention (device structure is shown in structural formula (2)).

Fig. 8 is a luminous efficiency-current density curve of OLEDs with different period numbers n proposed by the present invention (device structure is shown in structural formula (2)).

Fig. 9 is the EL spectrogram (device structure as shown in structural formula (2)) and the EL spectrogram (normalized) of the device with structural formula (5) that the present invention proposes to have the OLEDs of different period number n, wherein curve n=0 in (a), n=2 in curve (b), n=4 in curve (c), n=6 in curve (d), and the device structure corresponding to curve (e) is as structural formula (5).

The content of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the present invention is not limited to the following preferred embodiments, which are merely illustrative embodiments of the present invention.

Detailed ways

For reference, the abbreviations and full names of the organic materials involved in this manual are listed as follows:

Table 1

In order to set forth the specific implementation mode and the embodiment of the present invention more clearly, the following points are now described:

① The light-emitting region of the OLEDs proposed by the present invention is located in the electron transport layer or/and the hole transport layer;

② The hole transport layer, electron transport layer, buffer layer and transition layer of OLEDs proposed by the present invention are all organic functional layers of OLEDs.

The first structure of the organic electroluminescent device proposed by the present invention is shown in Figure 1, wherein: 1 is a transparent substrate, which can be glass or a flexible substrate, and the flexible substrate is made of polyester or polyimide One of the materials in the compound; 2 is the first electrode layer (anode layer), which can use inorganic materials or organic conductive polymers. Inorganic materials are generally metal oxides such as indium tin oxide (hereinafter referred to as ITO), zinc oxide, and tin zinc oxide. material or gold, copper, silver and other metals with higher work functions, the optimal choice is ITO, and the organic conductive polymer is preferably a material in PEDOT and PANI; 3 is a buffer layer, generally using phthalocyanines, polyacrylic acid A material in esters, polyimides, fluoropolymers, inorganic fluoride salts, inorganic oxides or diamonds, the present invention is preferably CuPc; 4 is a hole transport layer, using an organic quantum well structure, which A kind of quantum well transport structure is made up of the organic material A of wide energy band and the organic material B of narrow energy band two kinds of material layers alternately overlapping, and the energy level of these two kinds of materials matches each other (namely satisfying above-mentioned relationship formula (I) and ( II), the energy band of material A can realize the wrapping of the energy band of material B), and due to the energy level barrier effect of the material A layer on the material B layer, the potential wells of electrons and holes are in the material B layer, Material A is one of triphenylamines (such as NPB, TPD, MTDATA), carbazoles (such as PVK, BCP, Bphen), pyrrolines or oxadiazoles (such as TPBi, PBD) compounds, and material B It is a material in phthalocyanine (such as CuPc, H ₂ Pc, VOPc) compounds. The first structure is preferably a multilayer quantum well structure of (NPB/CuPc) _n . The HOMO energy levels of NPB and CuPc are respectively - 5.5eV, -4.8eV, LUMO are -2.5eV, -2.7eV respectively, from the energy level diagram of the device (see Figure 2, Figure 3) that preferably (NPB/CuPc) _n is used as the hole transport layer, it can be seen that, Due to the barrier effect of the NPB layer on the CuPc layer, a potential well of electrons and holes is formed in the CuPc layer; 5 is the transition layer, which adopts a material that matches the energy level of the electron transport layer material. The layered quantum well structure is preferably (NPB/CuPc) _n , and the transition layer is preferably NPB; 6 is the electron transport layer, which is generally a metal-organic complex or an oxadiazole compound, and is preferably Alq ₃ , Al (Saph-q), Ga(Saph-q), Zn(Ac) ₂ ; 7 is the second electrode layer (cathode layer, metal layer), generally lithium, magnesium, calcium, strontium, aluminum, For metals with lower work functions such as indium or their alloys with copper, gold, and silver, the present invention is preferably a sequential Mg:Ag alloy layer and Ag layer; 8 is a power supply.

The preferred OLEDs of the above-mentioned first structure have the following structural formula (1):

Glass/ITO/CuPc/(NPB/CuPc) _n /NPB/Alq ₃ /Mg:Ag/Ag (1)

Where n is the period number of the NPB/CuPc quantum well, and the value of n can be an integer of 1-10. According to the above structural formula (1), the detailed implementation of the preparation steps in conjunction with the device is set forth as follows:

① Clean the transparent conductive substrate ITO glass by using boiling detergent ultrasonic and deionized water ultrasonic method, and place it under the infrared lamp to dry, in which the ITO film on the conductive substrate is used as the anode layer of the device, and the ITO film The sheet resistance is 5Ω～100Ω, and the film thickness is 80.0～280.0nm;

② Put the cleaned and dried ITO glass in a vacuum chamber with a pressure of 1×10 ^-5 ~ 5×10 ^-3 Pa, evaporate a layer of CuPc on the above ITO film as the buffer layer of the device, and the evaporation of the film The plating rate is 0.02-0.4nm/s, and the film thickness is 0.5-20.0nm;

③ Continue to vapor-deposit a hole transport layer on the above-mentioned CuPc buffer layer. The hole transport layer adopts an alternating n-period NPB/CuPc organic multi-quantum well structure, wherein the vapor deposition rate of the CuPc film is 0.02-0.4nm/s, The film thickness of each layer of CuPc in the quantum well structure is 0.5-10.0nm, the evaporation rate of the NPB film is 0.1-0.6nm/s, and the film thickness of each layer of NPB in the quantum well structure is 0.5-30.0nm;

④ Continue to vapor-deposit a layer of NPB on the above-mentioned hole transport layer as the transition layer of the device, the evaporation rate of the film is 0.1-0.6nm/s, and the film thickness is 10.0-45.0nm;

⑤ Continue to vapor-deposit Alq ₃ on the above-mentioned NPB transition layer as the electron transport layer and electroluminescent layer of the device, the evaporation rate of the film is 0.1-0.6nm/s, and the film thickness is 40.0-100.0nm;

⑥Finally, Mg:Ag alloy layer and Ag layer are sequentially vapor-deposited on the above-mentioned Alq ₃ film as the cathode layer of the device, wherein the ratio of Mg and Ag vapor deposition rates in the alloy layer is 10:1, and the total vapor deposition rate is 0.6～ 2.0nm/s, the total evaporation thickness is 50.0-200.0nm, the evaporation rate of the Ag layer is 0.3-0.8nm/s, and the thickness is 40.0-200.0nm.

The second structure of the organic electroluminescent device proposed by the present invention is as shown in Figure 1 (no buffer layer 3), wherein: 1, 2 are the same as the above-mentioned first structure; 4 is a hole transport layer, adopting an organic quantum well structure , this kind of quantum well transport structure is composed of two material layers, the organic material A with a wide energy band and the organic dye C with a narrow energy band. and (II), the energy band of material A can realize the wrapping of the energy band of material C), and due to the energy level barrier effect of the material A layer on the material C layer, the potential wells of electrons and holes are in the material C layer Among them, material A is a material in triphenylamines (such as NPB, TPD, MTDATA), carbazoles (such as PVK, BCP, Bphen), pyrrolines or oxadiazoles (such as TPBi, PBD) compounds, Material C is a material among polyphenylene (such as rubrene, pentacene), coumarin (such as C545T) or bispyran (such as DCJTB, DCM) compounds, and the second structure is preferably (NPB/rubrene) The multilayer quantum well structure of n, the HOMO energy levels of NPB and rubrene are -5.5eV, -5.4eV respectively, and the LUMO energy levels are -2.5eV, -3.2eV respectively, from the preferred (NPB/rubrene)n as holes The schematic diagram of the energy level of the device of the transport layer (see Figure 6) can be seen, due to the energy level barrier at the interface between the NPB layer and the rubrene layer, hole carriers in the device can be enriched and bound in the rubrene layer; 5 is the transition layer, adopting materials that match the energy level of the electron transport layer, if the multilayer quantum well structure of the hole transport layer is preferably (NPB/rubrene) _n , the transition layer is preferably NPB; 6, 7 are the same as the above-mentioned first a structure.

The preferred OLEDs of the above-mentioned second structure have the following structural formula (2):

Glass/ITO/(NPB/rubrene)n/NPB/Alq ₃ /Mg:Ag/Ag (2)

Where n is the period number of the NPB/rubrene quantum well, and the value of n can be an integer of 1-10. According to the above structural formula (2), the detailed implementation of the preparation steps in conjunction with the device is set forth as follows:

① Clean the transparent conductive substrate ITO glass by using boiling detergent ultrasonic and deionized water ultrasonic method, and place it under the infrared lamp to dry, in which the ITO film on the conductive substrate is used as the anode layer of the device, and the ITO film The sheet resistance is 5Ω～100Ω, and the film thickness is 80.0～280.0nm;

② Put the cleaned and dried ITO glass in a vacuum chamber with a pressure of 1×10 ^-5 ~ 5×10 ^-3 Pa, and evaporate a hole transport layer on the above ITO film. The hole transport layer adopts alternating The n-period NPB/rubrene organic multi-quantum well structure, in which the evaporation rate of the rubrene film is 0.02-0.4nm/s, the film thickness of each layer of rubrene in the quantum well structure is 0.5-10.0nm, and the evaporation rate of the NPB film 0.1-0.6nm/s, and the film thickness of each layer of NPB in the quantum well structure is 0.5-30.0nm;

③Continue to vapor-deposit a layer of NPB on the above-mentioned hole transport layer as the transition layer of the device, the evaporation rate of the film is 0.1-0.6nm/s, and the film thickness is 10.0-45.0nm;

④ Continue to vapor-deposit _Alq3 on the above-mentioned NPB transition layer as the electron transport layer and electroluminescent layer of the device, the evaporation rate of the film is 0.1-0.6nm/s, and the film thickness is 40.0-100.0nm;

⑤Finally, Mg:Ag alloy layer and Ag layer are sequentially vapor-deposited on the above-mentioned _Alq3 film as the cathode layer of the device, wherein the ratio of Mg and Ag vapor deposition rates in the alloy layer is 10:1, and the total vapor deposition rate is 0.6～ 2.0nm/s, the total evaporation thickness is 50.0-200.0nm, the evaporation rate of the Ag layer is 0.3-0.8nm/s, and the thickness is 40.0-200.0nm.

Example 1-3

Three OLEDs were prepared in the same manner as the device shown in formula (1) above. Moreover, in order to facilitate the comparison of device performance, the thickness of the ITO layer of the three OLEDs is 200.0nm, the film thickness of the CuPc buffer layer is 6.0nm, the film thickness of the NPB transition layer is 15.0nm, and the film thickness of the Alq ₃ electron transport layer The thickness is 60.0nm, the thickness of the Mg:Ag alloy layer and the Ag layer are 100.0nm respectively, the film thickness of each layer of the alternating NPB/CuPc film in the three OLEDs varies with the number of periods n, and the n period The total film thicknesses of the NPB and CuPc thin films were 15.0 nm and 6.0 nm, respectively. The structures of the three OLEDs are shown in Tables 2 and 3 below. The brightness-current density curves and luminous efficiency-current density curves of the devices are shown in Figure 4 and Figure 5, respectively.

Comparative example 1

Prepare a traditional OLED with the same method as embodiment 1-3, but do not prepare alternate NPB/CuPc film (n=0) in this traditional device, the film thickness of CuPc shown in table 3 below, NPB layer is respectively 12.0 nm, 30.0nm. The device has the following structural formula (3):

Glass/ITO/CuPc/NPB/Alq ₃ /Mg:Ag/Ag (3)

In OLEDs with NPB/CuPc organic quantum well structure as the hole transport layer, the effect of the period number n on the device performance is shown in Table 3 below.

Table 2 no OLED structure Comparative example 1 embodiment 1 embodiment 2 embodiment 3 0246 Glass/ITO/CuPc(12.0nm)/NPB(30.0nm)/Alq ₃ (60.0nm)/Mg:Ag/AgGlass/ITO/CuPc(6.0nm)/[NPB(7.5nm)/CuPc(3.0nm)] ₂ /NPB(15.0nm)/Alq ₃ (60.0nm)/Mg:Ag/AgGlass/ITO/CuPc(6.0nm)/[NPB(3.8nm)/CuPc(1.5nm)] ₄ /NPB(15.0nm)/ Alq ₃ (60.0nm)/Mg:Ag/AgGlass/ITO/CuPc(6.0nm)/[NPB(2.5nm)/CuPc(1.0nm)] ₆ /NPB(15.0nm)/Alq ₃ (60.0nm)/Mg : Ag/Ag

table 3 Comparative example 1 Example 1 Example 2 Example 3 number of cycles 0 2 4 6 layer Material Film thickness/nm Anode layer ITO 200.0 The buffer layer CuPe 12.0 6.0 6.0 6.0 hole transport layer NPB 0 7.5 3.8 2.5 CuPc 0 3.0 1.5 1.0 transition layer NPB 30.0 15.0 15.0 15.0 electron transport layer Alq ₃ 60.0 cathode layer Mg:Ag 100.0 Ag 100.0 device Current density/A/m ² 400 Brightness/cd/ ^m2 1400 1960 3900 800 parameter Luminous efficiency/cd/A 3.8 4.3 9.8 2.3 Initial brightness/cd/m ² 1000 T _1/2 /h 2.5 2.7 3.5 2 Life/h 25 27 35 20

It can be seen from Table 3 that under the experimental conditions of the present invention, when the number of quantum well periods is 4, the device performance is the best. When the current density is 34mA/cm ² , the highest efficiency of the corresponding device can reach 10.8cd/A, which is the highest reported efficiency of bulk luminescence of Alq ₃ undoped dye in the work so far. Compared with the traditional device (n=0), the performance of the device is improved by nearly 3 times.

When the number of quantum well periods is 6, because the material thickness of each layer in the quantum well is too thin, the quality of the film formation becomes poor, thereby reducing the performance of the device. Generally speaking, as the number of cycles increases, and if the thickness of each layer in the quantum well is not too low (thickness with guaranteed film quality), the device performance will increase.

Example 4

The ITO glass with a square resistance of 15 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, where the film thickness of ITO was 180.0 nm. Place the dried ITO glass in a vacuum chamber with a pressure of 1×10 ^-3 Pa, and use thermal evaporation to evaporate a CuPc buffer film on the ITO film. The evaporation rate is 0.04nm/s and the film thickness is 6.0nm. . On the CuPc buffer film, continue to vapor-deposit alternating multi-layer hole transport layers (NPB/CuPc) ₆ , where the evaporation rate of the NPB film is 0.2nm/s, the film thickness is 3.8nm, and the evaporation rate of the CuPc film is 0.04nm /s, the film thickness is 1.5nm. Continue to vapor-deposit a 15.0nm NPB layer as a transition layer on the hole transport layer at a vapor deposition rate of 0.4nm/s, and continue to vapor-deposit an organic functional layer Alq ₃ at a vapor deposition rate of 0.2nm/s. The thickness is 60.0nm. Continue to vapor-deposit the metal layer on the Alq ₃ layer, the metal layer is composed of Mg:Ag alloy layer and Ag layer in turn, the ratio of Mg and Ag vapor deposition rate in the alloy layer is 10:1, and the total vapor deposition rate is 1.5nm/s , the film thickness is 100.0nm; the evaporation rate of Ag is 0.5nm/s, and the evaporation thickness is 100.0nm. The turn-on voltage of the device is 2.5V, the maximum luminous brightness is 16000cd/m ² , and when the current density is 36mA/cm ² , the corresponding maximum luminous efficiency is 10.8cd/A.

Example 5

The ITO glass with a square resistance of 60 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, where the film thickness of ITO was 100.0 nm. Place the dried ITO glass in a vacuum chamber with a pressure of 2×10 ^-3 Pa, and use thermal evaporation to evaporate a CuPc buffer film on the ITO film. The evaporation rate is 0.06nm/s, and the film thickness is 8.0nm. . Continuously vapor-deposit alternate multilayer hole transport layers (NPB/CuPc) ₂ on the CuPc buffer film, wherein the evaporation rate of the NPB film is 0.2nm/s, the film thickness is 7.5nm, and the evaporation rate of the CuPc film is 0.06nm /s, the film thickness is 3.0nm. Continue to vapor-deposit a 20.0nm NPB layer on the hole transport layer as a transition layer, the evaporation rate is 0.2nm/s, and continue to evaporate the organic functional layer Al(Saph-q), and the evaporation rate is 0.2nm /s, the film thickness is 60.0nm. On the Al(Saph-q) layer, the metal layer is continuously evaporated. The metal layer is composed of Mg:Ag alloy layer and Ag layer in turn. The Mg and Ag evaporation rate ratio in the alloy layer is 10:1, and the total evaporation rate is 1.5nm/s, the film thickness is 150.0nm; the evaporation rate of Ag is 0.4nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.8V, and the maximum luminance is 13000cd/m ² .

Example 6

The ITO glass with a square resistance of 30 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp. The film thickness of ITO was 140.0 nm. Place the dried ITO glass in a vacuum chamber with a pressure of 1.5×10 ^-3 Pa, and use thermal evaporation to evaporate a CuPc buffer film on the ITO film. The evaporation rate is 0.03nm/s, and the film thickness is 4.0nm. . On the CuPc buffer film, continue to vapor-deposit alternating multi-layer hole transport layers (NPB/CuPc) ₈ , where the evaporation rate of the NPB film is 0.2nm/s, the film thickness is 2.0nm, and the evaporation rate of the CuPc film is 0.02nm /s, the film thickness is 0.75nm. Continue to vapor-deposit a 20.0nm NPB layer on the transport layer as a transition layer structure at a vapor deposition rate of 0.2nm/s, and continue to vapor-deposit an organic functional layer Zn(Ac) ₂ at a vapor deposition rate of 0.2nm/s , the film thickness is 60.0nm. On the Zn(Ac) ₂ layer, continue to vapor-deposit the metal layer. The metal layer is composed of Mg:Ag alloy layer and Ag layer in turn. nm/s, the film thickness is 180.0nm; the evaporation rate of Ag is 0.5nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.9V, and the maximum luminance is 12000cd/m ² .

Example 7-9

Three OLEDs were prepared in the same manner as the device shown in structural formula (2) above. And in order to facilitate the comparison of device performance, the thickness of the ITO layer of the three OLEDs is 240.0nm, the total film thickness of the NPB film (including the transition layer) is 40.0nm, and the total film thickness of the n-period rubrene film is 8.0nm , the film thickness of the Alq ₃ electron transport layer is 60.0nm, the thickness of the Mg:Ag alloy layer and the Ag layer are 100.0nm respectively, but the film thickness of each rubrene film of the alternating NPB/rubrene film in the three OLEDs varies with The number of cycles n varies, and the film thickness of each layer of NPB film is 5.0nm. The structures of the three OLEDs are shown in Tables 4 and 5 below. The brightness-current density curves and luminous efficiency-current density curves of the devices are shown in Figure 7 and Figure 8, respectively.

Comparative example 2

A traditional OLED was prepared by the same method as in Examples 7-9, in which no alternate NPB/rubrene thin film (n=0) was prepared, and the film thickness of the NPB layer shown in Table 4 below was 40.0 nm. The device has the following structural formula (4):

Glass/ITO/NPB/Alq ₃ /Mg:Ag/Ag (4)

Table 4 no OLED structure Comparative example 2 embodiment 7 embodiment 8 embodiment 9 0246 Glass/ITO/NPB(40.0nm)/Alq ₃ (60.0nm)/Mg:Ag/AgGlass/ITO/[NPB(5.0nm)/rubrene(4.0nm)] ₂ /NPB(30.0nm)/Alq ₃ (60.0 nm)/Mg:Ag/AgGlass/ITO/[NPB(5.0nm)/rubrene(2.0nm)] ₄ /NPB(20.0nm)/Alq ₃ (60.0nm)/Mg:Ag/AgGlass/ITO/[NPB( 5.0nm)/rubrene(1.3nm)] ₆ /NPB(10.0nm)/Alq ₃ (60.0nm)/Mg:Ag/Ag

Comparative example 3

Prepare a traditional OLED with the same method as embodiment 7-9, do not prepare alternating NPB/rubrene thin film (n=0) in this traditional device, but electron transport layer is the Alq of 60.0nm thick doping 2wt% rubrene layer, the device structure is shown in Table 5 below, and the device has the following structural formula (5):

Glass/ITO/NPB/Alq ₃ :rubrene(2wt%)/Mg:Ag/Ag (5)

Figure 9 shows the EL spectrograms of the OLEDs above, and curves (a), (b), (c), and (d) correspond to organic electroluminescent devices with quantum well periods of 0, 2, 4, and 6, respectively, Curve (e) corresponds to a device with formula (5) above (yellow light emission from rubrene). We observe that the EL spectrum of the device with the NPB/rubrene organic quantum well structure of the present invention moves significantly with the increase of the period number n. The device of n=0 (curve a) emits the green luminescence of Alq ₃ at 520nm, but it can be seen from the EL spectra of the device of n=2 (curve b) and the device of n=4 (curve c) that rubrene has appeared The luminescence is accompanied by a shoulder peak of Alq ₃ material near 520nm. It is worth pointing out that the luminescence of the n=6 device (curve d) is basically all rubrene luminescence, and the luminescence of Alq ₃ is almost invisible, and the spectral peak of the traditional device without quantum well structure (curve e) is basically It is consistent, which means that the carriers are only confined in the rubrene layer for recombination.

The above work has confirmed that the organic quantum well structure can not only regulate the transport of holes, but also control the luminescent center of the device by changing the number of organic quantum well cycles.

The introduction of an organic quantum well hole transport structure in an organic electroluminescent device can effectively control the transport of holes in the device, thereby helping to obtain a balance between electron and hole injection, and then improve the luminous efficiency of the device. At the same time, due to the use of dyes in the organic quantum well structure to form separate layers, the study of EL spectroscopy shows that the luminescent center of the device can be effectively controlled by changing the period number of the quantum well, which provides a useful reference for realizing different colors of luminescence.

In OLEDs with NPB/rubrene organic quantum well structure as the hole transport layer, the effect of the period number n on the device performance is shown in Table 5 below.

table 5 Comparative example 2 Example 7 Example 8 Example 9 Comparative example 3 number of cycles 0 2 4 6 0 layer Material Film thickness/nm Anode layer ITO 240.0 hole transport layer NPB 0 5.0 5.0 5.0 0 rubrene 0 4.0 2.0 1.3 0 transition layer NPB 40.0 30.0 20.0 10.0 40.0 electron transport layer Alq ₃ 60.0 60.0 60.0 60.0 60.0 (doped with 2wt% rubrene) cathode layer Mg:Ag 100.0 Ag 100.0 Device parameters Current density/A/m ² 3000 Brightness/cd/ ^m2 6160 9000 17800 13500 Luminous efficiency/cd/A 2.01 3.03 6.00 4.46 Luminous wavelength/nm 528 548 556 560 564

It can be seen from Table 5 that under the experimental conditions of the present invention, when the number of quantum well periods n is 4, the brightness and luminous efficiency of the device are the best. When the number of quantum well periods is 6, because the thickness of each layer in the quantum well is too thin to form a high-quality continuous film, the structure of the quantum well is destroyed, and the device efficiency decreases instead. Therefore, on the premise of not destroying the quantum well structure, increasing the period number of the device can further improve the efficiency of the device. At the same time, we can also find that with the increase of the period number n, the proportion of rubrene luminescence in the luminescence of the device is getting higher and higher, so that the color of the EL spectrum is red-shifted, which fully proves that the luminescence center of the device moves toward rubrene layer transfer. Moreover, the higher the period number n of the organic quantum well is, the more favorable it is to transfer light to the rubrene layer.

Examples 10-13

The devices of Examples 10-13 were prepared in the same manner as in Examples 7-9, and the number of cycles of each device was 4, and the structures of the devices were shown in Table 6 below. In OLEDs with NPB/rubrene organic quantum well structure as the hole transport layer, the influence of NPB film thickness on device performance is also shown in Table 6 below.

Table 6 Example 10 Example 11 Example 12 Example 13 number of cycles 4 layer Material Film thickness/nm Anode layer ITO 240.0 240.0 240.0 240.0 hole transport layer NPB 1.0 3.0 5.0 7.0 rubrene 2.0 transition layer NPB 36.0 28.0 20.0 12.0 electron transport layer Alq ₃ 60.0 cathode layer Mg:Ag 100.0 Ag 100.0 Device parameters Current density/A/m ² 3000 Brightness/cd/ ^m2 15000 24000 18000 17400 Luminous efficiency/cd/A 5.00 8.00 6.00 5.80

It can be seen from Table 6 that when the thickness of the NPB layer is 3.0nm, the performance of the device is the best. However, when the thickness is 1.0 nm, the performance of the device is degraded due to the destruction of the quantum well structure. Therefore, the thinner the NPB layer is, the more beneficial it is to improve device performance.

Examples 14-17

The devices of Examples 14-17 were prepared by the same method as in Examples 7-9, and the number of cycles of each device was 4, and the structures of the devices were shown in Table 7 below. In OLEDs whose hole transport layer adopts NPB/rubrene organic quantum well structure, the effect of rubrene film thickness on device performance is also shown in Table 7 below.

Table 7 Example 14 Example 15 Example 16 Example 17 number of cycles 4 layer Material Film thickness/nm Anode layer ITO 240.0 hole transport layer NPB 5.0 rubrene 1.0 2.0 4.0 6.0 transition layer NPB 20.0 electron transport layer Alq ₃ 60.0 cathode layer Mg:Ag 100.0 Ag 100.0 Device parameters Current density/A/m ² 3000 Brightness/cd/ ^m2 10500 18000 15000 15000 Luminous efficiency/cd/A 3.50 6.00 5.00 5.00

It can be seen from Table 7 that changing the thickness of the rubrene layer has little effect on the device performance. In addition to destroying the quantum well structure at 1.0nm, a relatively thin thickness can be selected according to process conditions. The present invention is preferably 2.0 nm.

Examples 18-21

The devices of Examples 18-21 were prepared in the same manner as in Examples 7-9, and the number of cycles of each device was 4. The structures of the devices are shown in Table 8 below. In the OLEDs whose hole transport layer adopts the organic quantum well structure, the influence of the electron transport layer material and the material change in the quantum well structure on the device performance is also shown in Table 8 below.

Table 8 Example 18 Example 19 Example 20 Example 21 layer Material Film thickness/nm number of cycles 4 Anode layer ITO 240.0 hole transport layer NPB barrier 5.0 5.0 5.0 5.0 potential well Material CuPc rubrene rubrene DCJTB 2.0 2.0 2.0 2.0 transition layer NPB 20.0 20.0 20.0 20.0 electron transport layer Material Alq ₃ Alq ₃ Al(Saph-q) Ga(Saph-q) 60.0 60.0 60.0 60.0 cathode layer Mg:Ag 100.0 Ag 100.0 Device parameters Current density/A/m ² 3000 Brightness/cd/ ^m2 22000 17800 25800 9500 Luminous efficiency/cd/A 7.03 5.90 8.60 3.17 Luminous wavelength/nm 528 550 560 620

Examples 22-24

The devices of Examples 22-24 were prepared in the same manner as in Examples 7-9, and the structures of the devices are shown in Table 9 below.

Comparative example 4

An OLED was prepared in the same manner as in Examples 22-24. In this device, alternate NPB/rubrene films (n=0) were not prepared. The device structure is shown in Table 9 below,

In OLEDs with NPB/rubrene organic quantum well structure as the hole transport layer, the effect of the period number n on the device lifetime is shown in Table 9 below.

Table 9 Comparative example 4 Example 22 Example 23 Example 24 number of cycles 0 1 4 6 layer Material Film thickness/nm Anode layer ITO 240.0 hole transport layer NPB 0 5.0 5.0 5.0 rubrene 0 8.0 2.0 1.3 transition layer NPB 40.0 35.0 20.0 10.0 electron transport layer Alq ₃ 60.0 cathode layer Mg:Ag 100.0 Ag 100.0 Device parameters Initial brightness/cd/m ² 1000 T ₁₂ /h 2.5 2.4 2.6 1.5 Life/h 25 twenty four 26 15

Example 25

The ITO glass with a square resistance of 60 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, where the film thickness of ITO was 100.0 nm. The dried ITO glass was placed in a vacuum chamber with a pressure of 2×10 ^-3 Pa, and alternately multi-layered hole transport layers (NPB/rubrene) ₄ were evaporated on the ITO film by thermal evaporation, in which the NPB film The evaporation rate is 0.2nm/s, the film thickness is 5.0nm, the evaporation rate of the rubrene thin film is 0.1nm/s, and the film thickness is 2.0nm. Continue to vapor-deposit a 20.0nm NPB layer on the hole transport layer as a transition layer, the evaporation rate is 0.2nm/s, and continue to evaporate the organic functional layer Al(Saph-q), and the evaporation rate is 0.2nm /s, the film thickness is 60.0nm. On the Al(Saph-q) layer, the metal layer is continuously evaporated. The metal layer is composed of Mg:Ag alloy layer and Ag layer in turn. The Mg and Ag evaporation rate ratio in the alloy layer is 10:1, and the total evaporation rate is 1.5nm/s, the film thickness is 150.0nm, the evaporation rate of Ag is 0.4nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.8V, and the maximum luminance is 16000cd/m ² .

Example 26

The ITO glass with a square resistance of 15 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, and the film thickness of ITO was 260.0nm. The dried ITO glass was placed in a vacuum chamber with a pressure of 1×10 ^-3 Pa, and a 10.0nm CuPc buffer layer was evaporated on the ITO film by thermal evaporation with an evaporation rate of 0.02nm/s. Thereafter, alternate multi-layer hole transport layers (NPB/rubrene) ₃ were evaporated on it, wherein the evaporation rate of the NPB thin film was 0.2nm/s, the film thickness was 5.0nm, and the evaporation rate of the rubrene thin film was 0.1nm/s s, the film thickness is 2.0 nm. Continue to vapor-deposit a 20.0nm NPB layer on the hole transport layer as a transition layer, the evaporation rate is 0.2nm/s, and continue to evaporate the organic functional layer Al(Saph-q), and the evaporation rate is 0.2nm /s, the film thickness is 60.0nm. On the Al(Saph-q) layer, the metal layer is continuously evaporated. The metal layer is composed of Mg:Ag alloy layer and Ag layer in turn. The Mg and Ag evaporation rate ratio in the alloy layer is 10:1, and the total evaporation rate is 1.5nm/s, the film thickness is 150.0nm; the evaporation rate of Ag is 0.4nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.5V, and the maximum luminance is 26000cd/m ² .

Example 27

The ITO glass with a square resistance of 100 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, where the film thickness of ITO was 60.0 nm. The dried ITO glass was placed in a vacuum chamber with a pressure of 2×10 ^-3 Pa, and the alternate multi-layer hole transport layer (MTDATA/rubrene) ₁₀ was evaporated on the ITO film by thermal evaporation, in which the MTDATA film The evaporation rate is 0.2nm/s, the film thickness is 5.0nm, the evaporation rate of the rubrene thin film is 0.1nm/s, and the film thickness is 2.0nm. Continue to vapor-deposit a 5.0nm NPB layer as a transition layer on the hole transport layer at a vapor deposition rate of 0.2nm/s, and continue to vapor-deposit an organic functional layer Alq ₃ at a vapor deposition rate of 0.2nm/s. The thickness is 60.0nm. Continue to vapor-deposit the metal layer on the Alq ₃ layer, the metal layer is composed of Mg:Ag alloy layer and Ag layer in turn, the ratio of Mg and Ag vapor deposition rate in the alloy layer is 10:1, and the total vapor deposition rate is 1.5nm/s , the film thickness is 150.0nm; the evaporation rate of Ag is 0.4nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.8V, and the maximum luminance is 14000cd/m ² .

Example 28

The ITO glass with a square resistance of 60 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, where the film thickness of ITO was 100.0 nm. The dried ITO glass was placed in a vacuum chamber with a pressure of 2×10 ^-3 Pa, and the alternate multi-layer hole transport layer (TPD/DCJTB) ₄ was evaporated on the ITO film by thermal evaporation, in which the TPD film The evaporation rate is 0.2nm/s, the film thickness is 5.0nm, the evaporation rate of the DCJTB thin film is 0.1nm/s, and the film thickness is 2.0nm. Continue to vapor-deposit a 20.0nm TPD layer on the hole transport layer as a transition layer at a vapor deposition rate of 0.2nm/s, and continue to vapor-deposit an organic functional layer Alq ₃ at a vapor deposition rate of 0.2nm/s. The thickness is 60.0nm. Continue to vapor-deposit the metal layer on the Alq ₃ layer, the metal layer is composed of Mg:Ag alloy layer and Ag layer in turn, the ratio of Mg and Ag vapor deposition rate in the alloy layer is 10:1, and the total vapor deposition rate is 1.5nm/s , the film thickness is 150.0nm; the evaporation rate of Ag is 0.4nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.8V, and the maximum luminance is 12000cd/m ² .

Example 29

The ITO glass with a square resistance of 40 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, where the film thickness of ITO was 150.0 nm. The dried ITO glass was placed in a vacuum chamber with a pressure of 1×10 ^-3 Pa, and the alternate multilayer hole transport layer (MTDATA/rubrene) ₄ was evaporated on the ITO film by thermal evaporation, in which the MTDATA film The evaporation rate is 0.2nm/s, and the film thickness is 5.0nm. The evaporation rate of the rubrene film is 0.2nm/s, and the film thickness is 2.0nm. Continue to vapor-deposit a 20.0nm MTDATA layer on the hole transport layer as a transition layer at a vapor deposition rate of 0.2nm/s, and continue to vapor-deposit an organic functional layer Alq ₃ at a vapor deposition rate of 0.2nm/s. The thickness is 60.0nm. Continue to vapor-deposit the metal layer on the Alq ₃ layer, the metal layer is composed of Mg:Ag alloy layer and Ag layer in turn, the ratio of Mg and Ag vapor deposition rate in the alloy layer is 10:1, and the total vapor deposition rate is 1.5nm/s , the film thickness is 150.0nm; the evaporation rate of Ag is 0.4nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.8V, and the maximum luminance is 18000cd/m ² .

Example 30

The ITO glass with a square resistance of 10 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, and the film thickness of ITO was 280.0nm. Place the dried ITO glass in a vacuum chamber with a pressure of 4×10 ^-3 Pa, and use thermal evaporation to vapor-deposit alternate multilayer hole transport layers (NPB/C545T) ₄ on the ITO film, in which the NPB film The evaporation rate is 0.2nm/s, and the film thickness is 5.0nm. The evaporation rate of the C545T film is 0.1nm/s, and the film thickness is 2.0nm. Continue to vapor-deposit a 20.0nm NPB layer on the hole transport layer as a transition layer at a vapor deposition rate of 0.2nm/s, and continue to vapor-deposit an organic functional layer Alq ₃ at a vapor deposition rate of 0.2nm/s. The thickness is 60.0nm. Continue to vapor-deposit the metal layer on the Alq ₃ layer, the metal layer is composed of Mg:Ag alloy layer and Ag layer in turn, the ratio of Mg and Ag vapor deposition rate in the alloy layer is 10:1, and the total vapor deposition rate is 1.5nm/s , the film thickness is 150.0nm; the evaporation rate of Ag is 0.4nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.5V, and the maximum luminance is 28000cd/m ² .

Example 31

The ITO glass with a square resistance of 20 Ω was cleaned by boiling detergent ultrasonic and deionized water ultrasonically, and dried under an infrared lamp, where the film thickness of ITO was 220.0nm. The dried ITO glass was placed in a vacuum chamber with a pressure of 3×10 ^-3 Pa, and the alternate multilayer hole transport layer (MTDATA/DCM) ₅ was evaporated on the ITO film by thermal evaporation, in which the MTDATA film The evaporation rate is 0.1nm/s, the film thickness is 5.0nm, the evaporation rate of the DCM thin film is 0.05nm/s, and the film thickness is 2.0nm. Continue to vapor-deposit a 20.0nm NPB layer as a transition layer on the hole transport layer, and the evaporation rate is 0.2nm/s, and continue to evaporate the organic functional layer Bphen on the top, the evaporation rate is 0.2nm/s, and the film thickness is 0.2nm/s. 60.0nm. On the Bphen layer, the vapor deposition metal layer is continued, and the metal layer is successively composed of Mg: Ag alloy layer and Ag layer. The ratio of Mg and Ag vapor deposition rate in the alloy layer is 10: 1, and the total vapor deposition rate is 1.5nm/s. The film thickness is 150nm; the evaporation rate of Ag is 0.4nm/s, and the evaporation thickness is 50.0nm. The turn-on voltage of the device is 2.5V, and the maximum luminance is 28000cd/m ² .

Although the present invention has been described in conjunction with preferred embodiments, the present invention is not limited to the above-mentioned embodiments and accompanying drawings. It should be understood that under the guidance of the inventive concept, those skilled in the art can make various modifications and improvements, and the appended The claims outline the scope of the invention.

Claims (13)

1. An organic electroluminescence device, which device comprises a transparent substrate (1), a first electrode layer (2) and a second electrode layer (7), and is sandwiched between the first electrode layer (2), the second electrode layer The hole transport layer (4) and the electron transport layer (6) between the two electrode layers (7) are characterized in that: the hole transport layer (4) adopts an organic quantum well structure, and this quantum well transport structure consists of a wide energy The organic material A with a band and the organic material B with a narrow energy band overlap alternately with a certain number of periods, and the energy levels of these two organic materials satisfy the following relationship: (1) The highest occupied orbital energy level of organic material A is lower than the highest occupied orbital energy level of organic material B, (II) The lowest unoccupied orbital energy level of the organic material A is higher than that of the organic material B, wherein the period number of the organic quantum well structure is an integer of 1-10. 2. The organic electroluminescent device according to claim 1, characterized in that, the film thickness of the organic material A layer is 0.5-30.0 nm, and the film thickness of the organic material B layer is 0.5-10.0 nm . 3. The organic electroluminescent device according to claim 1, wherein the organic material B is a dye C. 4. The organic electroluminescent device according to claim 1, characterized in that, a buffer layer (3) is sandwiched between the first electrode layer (2) and the hole transport layer (4), the A transition layer (5) is sandwiched between the hole transport layer (4) and the electron transport layer (6). 5. The organic electroluminescent device according to claim 4, characterized in that, the buffer layer (3) is composed of copper phthalocyanine, and the transition layer (5) is composed of N, N'-di-( 1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine. 6. The organic electroluminescent device according to claim 1, characterized in that, the organic material A is a material in triphenylamines, carbazoles, pyrrolines or oxadiazoles, the The above-mentioned organic material B is a material among phthalocyanine compounds. 7. The organic electroluminescent device according to claim 6, wherein said triphenylamine compound comprises N, N'-di-(1-naphthyl)-N, N'-diphenyl- 1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(m-methylphenyl)-1,1'-biphenyl-4 , 4'-diamine or 4,4',4"-tris(3-methylphenylaniline) triphenylamine, the carbazole compounds include polyvinylcarbazole, 2,9-dimethyl- 4,7-diphenyl-1,10-phenanthroline or 4,7-diphenyl-1,10-phenanthroline, the oxadiazole compounds include tri-[1-phenyl -1H-benzimidazolyl]-(1,3,5-trisubstituted benzene) or 2-(4-tert-butylphenyl)-5-(4-biphenyl)-1,3,4-oxa Oxadiazole, the phthalocyanine compound includes copper phthalocyanine, phthalocyanine or vanadium phthalocyanine. 8. The organic electroluminescent device according to claim 7, characterized in that, said organic material A is N, N'-two-(1-naphthyl)-N, N'-diphenyl-1 , 1'-biphenyl-4,4'-diamine, the organic material B is copper phthalocyanine. 9 . The organic electroluminescent device according to claim 1 , characterized in that, the electron transport layer ( 6 ) is made of a metal-organic complex or an oxadiazole compound. 10. organic electroluminescent device according to claim 9, is characterized in that, described electron transport layer (6) adopts three (8-hydroxyquinoline) aluminum, (salicylaldehyde anteline phenol)-( One of 8-hydroxyquinoline)aluminum(III), (salicylaldehyde ortho-aminophenol)-(8-hydroxyquinoline)gallium(III) or 4-hydroxyacridine zinc. 11. The organic electroluminescence device according to claim 3, characterized in that, the organic material A is a material in triphenylamines, carbazoles, pyrrolines or oxadiazoles, and The organic dye C mentioned above is a material among polyphenylene, coumarin or bispyran compounds. 12. The organic electroluminescent device according to claim 11, wherein the polyphenylene compound comprises 5,6,11,12-tetraphenyltetracene or pentacene, and the aromatic Soybean dyes include 10-(2-benzothiazole)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[1]pyridine Pyran [6,7,8-ij] quinolinazine, the bispyran compound includes 4-dicyanomethylene-2-tert-butyl-6-(1,1,7,7-tetra Methyl-julonidine-9-vinyl)-4H-pyran or 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran. 13. The organic electroluminescence device according to claim 12, wherein said organic material A is N, N'-two-(1-naphthyl)-N, N'-diphenyl-1 , 1'-biphenyl-4,4'-diamine, the organic dye C is 5,6,11,12-tetraphenyltetracene.

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