阅读说明：本技术 化合物、发光层、有机化合物层及发光器件 (Compound, light-emitting layer, organic compound layer, and light-emitting device ) 是由 张东旭 邱丽霞 高荣荣 于 2021-07-16 设计创作，主要内容包括：本申请涉及有机发光技术领域,具体而言,涉及一种化合物、发光层、有机化合物层及发光器件,该化合物的结构为,在化合物的共轭平面内,跃迁偶极矩的延伸方向为长轴方向,垂直于所述跃迁偶极矩的方向为短轴方向,所述化合物基于所述共轭平面形成投影面,所述投影面在所述长轴方向上的长度为L,所述投影面在所述短轴方向上的长度为S,所述L与所述S的比值大于1.5。本发明提供了一种通过在共轭平面上,化合物的结构在跃迁偶极矩的方向上的长度相较于其在垂直于跃迁偶极矩的方向上的长度越长,分子越倾向水平蒸镀在基底表面上,提高光耦合效率和光照强度,从而保证发光器件的发光性能。(The application relates to the technical field of organic light emitting, in particular to a compound, a light emitting layer, an organic compound layer and a light emitting device, wherein the compound has a structure that in a conjugate plane of the compound, the extension direction of a transition dipole moment is the long axis direction, the direction perpendicular to the transition dipole moment is the short axis direction, the compound forms a projection plane based on the conjugate plane, the length of the projection plane in the long axis direction is L, the length of the projection plane in the short axis direction is S, and the ratio of L to S is greater than 1.5. The invention provides a method for improving light coupling efficiency and illumination intensity by that on a conjugate plane, the longer the length of a compound structure in a transition dipole moment direction is compared with the length of the compound structure in a direction vertical to the transition dipole moment direction, the more molecules tend to be horizontally evaporated on the surface of a substrate, thereby ensuring the light emitting performance of a light emitting device.)

1. A compound characterized in that, in a conjugate plane of said compound, an extending direction of a transition dipole moment is a long axis direction and a direction perpendicular to said transition dipole moment is a short axis direction, said compound forms a projection plane based on said conjugate plane, a length of said projection plane in said long axis direction is L, a length of said projection plane in said short axis direction is S, and a ratio of said L to said S is greater than 1.5.

2. The compound of claim 1, wherein the ratio of L to S is greater than 1.8.

3. The compound of claim 1, wherein the compound has a molecular weight of less than 1000 g/mol.

4. The compound of claim 1, having the structure:

wherein A is an independent aryl ring or heteroaryl ring, and B is an independent aryl ring or heteroaryl ring.

5. The compound of claim 4, wherein at least one of-H in A and/or B is substituted.

6. The compound of claim 1, having the structure:

wherein, L1, L2, L3, R1 and R2 are all alkyl, aryl or heteroaryl.

7. The compound of claim 6, wherein said L1, said L2, said L3, said R1, and said R2 are each a substitutable alkyl, aryl, or heteroaryl group.

8. A light-emitting layer comprising a blue fluorescent light-emitting layer comprising the compound according to any one of claims 1 to 7.

9. An organic compound layer comprising the light-emitting layer according to any one of claims 8.

10. A light-emitting device comprising a first electrode, a second electrode, and the organic compound layer according to claim 9, wherein the organic compound layer is located between the first electrode and the second electrode.

Technical Field

The present application relates generally to the field of organic light emitting technology, and more particularly, to a compound, a light emitting layer, an organic compound layer, and a light emitting device.

Background

The organic electroluminescent device has the characteristics of active light emission, high brightness, high resolution, wide viewing angle, high response speed, low energy consumption, flexibility and the like, and is gradually attracted by people as a new generation display technology. An organic electroluminescent device generally includes an anode, a hole transport layer, an electroluminescent layer as an energy conversion layer, an electron transport layer, and a cathode, which are sequentially stacked. When voltage is applied to the anode and the cathode, the two electrodes generate an electric field, electrons on the cathode side move to the electroluminescent layer under the action of the electric field, holes on the anode side also move to the luminescent layer, the electrons and the holes are combined in the electroluminescent layer to form excitons, and the excitons transfer energy to the fluorescent guest material and emit light through Forster energy transfer and Dexter energy transfer modes. In recent years, in order to meet the demands of users, it has become important to improve the light emitting performance of organic electroluminescent devices.

Disclosure of Invention

In order to improve the light emitting performance of an organic electroluminescent device in the prior art, the application provides a compound, a light emitting layer, an organic compound layer and a light emitting device.

In order to achieve the purpose of the invention, the following technical scheme is adopted in the application:

according to a first aspect of embodiments of the present application, there is provided a compound in which, in a conjugate plane of the compound, an extending direction of a transition dipole moment is a long axis direction, and a direction perpendicular to the transition dipole moment is a short axis direction, the compound forming a projection plane based on the conjugate plane, a length of the projection plane in the long axis direction being L, a length of the projection plane in the short axis direction being S, and a ratio of L to S being greater than 1.5.

According to an embodiment of the present application, wherein a ratio of said L to said S is greater than 1.8.

According to an embodiment of the present application, wherein the molecular weight of the compound should be less than 1000 g/mol.

According to an embodiment of the present application, wherein the compound has the structure:

wherein A is an independent aryl ring or heteroaryl ring, and B is an independent aryl ring or heteroaryl ring.

According to an embodiment of the application, at least one of-H in said a and/or said B is substituted.

According to an embodiment of the present application, wherein the compound has the structure:

wherein, L1, L2, L3, R1 and R2 are all alkyl, aryl or heteroaryl.

According to an embodiment of the present application, wherein said L1, said L2, said L3, said R1 and said R2 are each a substitutable alkyl, aryl or heteroaryl group.

According to a second aspect of embodiments of the present application, there is provided a light-emitting layer including a blue fluorescent light-emitting layer including the compound described above.

According to a third aspect of embodiments of the present application, there is provided an organic compound layer including the light-emitting layer described above.

According to a fourth aspect of the embodiments of the present application, there is provided a liquid crystal display device including a first electrode, a second electrode, and the organic compound layer described above, the organic compound layer being located between the first electrode and the second electrode.

According to the technical scheme, the compound, the light-emitting layer, the organic compound layer and the light-emitting device have the advantages and positive effects that:

the present application provides a compound in which an extending direction of a transition dipole moment is a long axis direction and a direction perpendicular to the transition dipole moment is a short axis direction within a conjugate plane of the compound, the compound forming a projection plane based on the conjugate plane, a length of the projection plane in the long axis direction being L, a length of the projection plane in the short axis direction being S, and a ratio of L to S being greater than 1.5. In summary, in the conjugated plane, the longer the length of the structure of the compound in the direction of the transition dipole moment is compared with the length thereof in the direction perpendicular to the transition dipole moment, the more the molecules tend to be horizontally evaporated on the substrate surface, improving the light coupling efficiency and the illumination intensity, thereby ensuring the light emitting performance of the light emitting device.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is a schematic diagram illustrating the molecular structure of a compound according to an exemplary embodiment.

Fig. 2 is a schematic structural view illustrating a horizontal direction of evaporated molecular transition dipole moments of a compound, a light emitting layer, an organic compound layer, and a light emitting device according to an exemplary embodiment.

Fig. 3 is a schematic structural view illustrating a vertical direction of evaporated molecular transition dipole moments of a compound, a light emitting layer, an organic compound layer, and a light emitting device according to an exemplary embodiment.

Fig. 4 is a molecular structure diagram illustrating a light emitting device according to an exemplary embodiment.

Fig. 5 is a diagram illustrating a compound, a light emitting layer, an organic compound layer, and a light emitting device according to an exemplary embodiment.

Fig. 6 is a molecular structure diagram illustrating a light emitting device according to an exemplary embodiment.

Fig. 7 is a graph illustrating performance of a BD-01 of one compound, a light emitting layer, an organic compound layer, and a light emitting device according to one exemplary embodiment.

Fig. 8 is a graph showing the performance of a BD-02 of one compound, a light emitting layer, an organic compound layer, and a light emitting device according to an exemplary embodiment.

Fig. 9 is a graph illustrating performance of a compound, a light emitting layer, an organic compound layer, and a BD-03 of a light emitting device according to an exemplary embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It is noted that in the description and claims of the present application and in the above-mentioned drawings, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

Also, the terms "comprises," "comprising," and "having," as well as any variations thereof or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the compound provided in the embodiments of the present disclosure is a compound composed of a blue fluorescent molecular structure, and the TDM direction in each drawing is the direction of the transition dipole moment.

Referring to fig. 1 to 8, an embodiment of the present disclosure provides a compound, in a conjugate plane of the compound, an extending direction of a transition dipole moment is a long axis direction, and a direction perpendicular to the transition dipole moment is a short axis direction, the compound forming a projection plane based on the conjugate plane, a length of the projection plane in the long axis direction being L, a length of the projection plane in the short axis direction being S, and a ratio of L to S being greater than 1.5.

Specifically, the conjugate plane of the compound is a plane formed by a plurality of atoms among a plurality of atoms constituting the compound, and the plane having the largest number of atoms among the plurality of atoms is the conjugate plane of the compound. In the conjugate plane, the extending direction of the transition dipole moment of the compound is the long axis direction, and the direction perpendicular to the transition dipole moment in the conjugate plane is the short axis direction. The increase in the ratio of the length of L to the length of S indicates that the longer the relative distance of the atoms in the direction of the transition dipole moment, the more the molecules tend to evaporate horizontally in the plane of the substrate as the relative length of the atoms of the compound in the direction of the transition dipole moment increases, and therefore the orientation of the compound also increases. In the using process of the compound, the luminescence of the compound is anisotropic, namely, the physical property and the orientation are closely related, and the measurement results of different orientations are different, so that the luminescence property can be improved by increasing the molecular orientation of the compound.

Optionally, the projection plane extends in the short axis direction at two ends of the long axis direction to form two short-side straight lines extending in the short axis direction. The two ends of the projection plane in the short axis direction extend along the long axis direction to form two long-side straight lines extending along the long axis direction. Enclosing a rectangular shape on the conjugate plane through two short-side straight lines and two long-side straight lines, wherein the sides of the rectangular shape extending along the transition dipole moment direction, namely the long sides of the rectangle, are L, and the length of the long sides is L; the side of the rectangular shape extending in a direction perpendicular to the dipole moment of the transition, i.e. the short side of the rectangle, i.e. the length of the short side, is S. Thus, to facilitate the location of the two short side lines and the location of the two long side lines that circumscribe a rectangle, the atoms of the compound have at least one atom on each side within the rectangle, the edges of the rectangle are determined by lines tangent to the outer edges of the atoms and extending in the direction of or perpendicular to the transition dipole moment, and the edges determine the values of L and S.

Referring to fig. 2 and 3, the direction of the dipole moment of the molecular transition in the completely horizontal state of the evaporated molecules is shown in fig. 2, and the direction of the dipole moment of the molecular transition in the completely vertical state of the evaporated molecules is shown in fig. 3. Since the light emitting direction is perpendicular to the transition dipole moment, the light emitting direction can be perpendicular to the substrate in the state that the molecules are completely horizontal, thereby improving the light emitting effect and reducing the light loss. On the contrary, in the vertical state of the evaporated molecules, the direction of the molecular transition dipole moment tends to be more parallel to the surface of the substrate, resulting in a decrease in the optical coupling efficiency and a deterioration in the light emission performance of the device.

Referring to fig. 1-8, further, the ratio of L to S is greater than 1.8. The relative distance between L and S is further optimized and selected to be increased, and the light extraction efficiency can be improved by controlling the orientation state of molecules, so that the light emitting performance of the light emitting device is improved.

In practical use, the external quantum efficiency of the light emitting device can be expressed by the following formula:

η_ext＝γη_rq_effη_out≡η_intη_out

wherein γ is a balance factor of carriers; eta r is the probability of radiating excitons, and the maximum of fluorescent molecules is 25%; q. q.s_effRadiative transition efficiency, related to the structure of the material itself; eta_outFor light out-coupling efficiency, it is related to the orientation of the molecules; therefore, the external quantum efficiency of the light-emitting device can be effectively improved by changing the orientation of the molecules, and the light-emitting effect of the light-emitting device is improved.

However, the luminescence of the compound is anisotropic, the physical properties and the orientations of the compound are closely opposite, the measurement results of different orientations are different, the luminescence intensity has angle dependence, and the luminescence direction faces to the direction perpendicular to the transition dipole moment of the compound, so the orientation of the transition dipole moment influences the angle of luminescence, and further influences the luminescence effect of the luminescent device. In addition, in the evaluation of the molecular orientation, it is not easy to directly observe how the actual transition dipole moment of the molecules, particularly the compound, of the light-emitting layer in the light-emitting element is oriented, and the orientation of the test compound can be performed by angle-dependent photoluminescence while guiding the structural design of the molecules by analysis.

Wherein the obtained parameter values are determined by performing the above method by calculating the molecular structure whose structure is optimized by molecular orbital calculation in which the most stable structure in the ground singlet state is calculated by the density functional method at the level of B3LYP/6-31G (d, p) calculation using a quantum chemical calculation program, while the direction of the transition dipole moment is determined by the time-dependent density functional method.

Further, since molecules of the compound have a high molecular orientation, the longer the length of L is compared with the length of S, the more the molecules tend to be horizontally deposited on the substrate plane, and the higher the light emission efficiency. However, in view of the workability of the compound, it is impossible to extend the atoms of the compound infinitely in the conjugated plane in the direction of the transition dipole moment. When the atoms of the compound are infinitely extended along the transition dipole moment direction on the conjugate plane of the compound, the compound cannot be evaporated when being actually applied in an evaporation environment, and the performance is affected. Thus, the molecular weight of the compound should be less than 1000 g/mol. By controlling the molecular weight, the situation that molecules of the compound cannot be evaporated on the substrate in the evaporation process due to overlarge molecular weight is avoided.

Further, the structure of the compound is:

wherein A is an independent aryl ring or heteroaryl ring, and B is an independent aryl ring or heteroaryl ring. By adopting the structure, the relative value of L and S of the molecule on the conjugate plane can be ensured to be relatively large, and the orientation of the molecule is the best at the moment.

Optionally, at least one of-H in said a and/or said B is substituted. the-H can be arranged in a substituted mode, the diversification of the structure is improved, the structure provided by the structure is based on the molecular structural formula of the compound, and therefore the ratio of L to S in a conjugated plane is relatively large, the molecular orientation is good, and the light-emitting performance is guaranteed.

Specifically, at least one hydrogen in the a may be substituted with a substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted diarylamino, substituted or unsubstituted diheteroarylamino, substituted or unsubstituted arylheteroarylamino, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, or substituted or unsubstituted aryloxy. Alternatively, at least one hydrogen in B may be substituted with a substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted diarylamino, substituted or unsubstituted diheteroarylamino, substituted or unsubstituted arylheteroarylamino, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, or substituted or unsubstituted aryloxy.

Referring to fig. 4 and 5, for fluorescent molecules with general structure with strong planarity, it is generally considered that the longer the molecular structure is, the better the molecular orientation is, and this theory is practical for some blue fluorescent molecules at present, but has a certain randomness; the main reason is that the fluorescence BD molecule with a double arylamine thickened ring structure has transition dipole moment along the N-N direction, the N-N direction is a long axis, and the orientation is obviously improved by adding a substituent, particularly increasing the length of a condensed ring in the N-condensed ring-N. Since it is difficult to increase the central condensed ring spacing in order to maintain the boron-nitrogen multiple resonance structure, improvement in orientation of the molecular structure is not significant by conventionally increasing the length at a or B.

The embodiments of the present application find that the transition dipole moment direction of the structure in the embodiments of the present disclosure can be coincided with the conventional improvement direction by adding an arylamine structure at the para-position of nitrogen at the a or B position of the boron-nitrogen structure to achieve the optimal performance, and it is noted that the technical effect of changing the transition dipole moment direction cannot be achieved by adding arylamine at the same time at the a position and the para-position benzene ring of B, and meanwhile, the technical effect of changing the transition dipole moment direction cannot be achieved by adding arylamine at the same time at the B position and the para-position benzene ring of a.

Referring to fig. 1 and 8, further, the structure of the compound is:

wherein, L1, L2, L3, R1 and R2 are all alkyl, aryl or heteroaryl. By adopting the form of the above structure, the orientation of the compound in the film can be increased in a simple manner.

Specifically, the L1, the L2, the L3, the R1, and the R2 are each a substitutable alkyl, aryl, or heteroaryl group.

Similarly, the above structure can improve the molecular orientation by adding an aromatic amine at the position of B. At the same time, the arrangement of L1 and the series structure provided on L1 at the position of a can also improve the orientation of the molecules.

Referring to fig. 1 to 8, embodiments of the present disclosure also provide a light emitting layer including a blue fluorescent light emitting layer including the above compound. It should be noted that, for the technical features of the compound in the light-emitting layer, reference may be made to the foregoing description, and further description is omitted here. The light-emitting layer disclosed in the embodiment of the present application includes the compound provided in the above embodiment, so that the light-emitting layer having the compound also has all the technical effects described above, and therefore, detailed description is omitted here, and other configurations of the light-emitting layer are known to those skilled in the art, and detailed description is omitted here.

Referring to fig. 1 to 8, embodiments of the present disclosure also provide an organic compound layer including the above-described light emitting layer.

Referring to fig. 1 to 8, embodiments of the present disclosure also provide a light emitting device including a first electrode, a second electrode, and the organic compound layer described above, the organic compound layer being located between the first electrode and the second electrode.

Further, the organic light-emitting device further comprises a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer and an electron injection layer which are sequentially arranged between the first electrode and the second electrode, and the organic compound layer is arranged between the electron blocking layer and the hole blocking layer. The first electrode is an anode, the anode is arranged on one side of the hole injection layer, which is far away from the hole transport layer, the second electrode is a cathode, and the cathode is arranged on one side of the electron injection layer, which is far away from the electron transport layer; and a light extraction layer is arranged on one side of the cathode, which is far away from the electron injection layer. It should be noted that, since the layered structure of the light emitting device is the prior art, the arrangement of the above layers and all the structural components of the organic light emitting device can be known by those skilled in the art according to common knowledge, and therefore, no structural layout diagram of the light emitting device is provided in the embodiments of the present disclosure.

Referring to fig. 1 to 8, embodiments of the present disclosure also provide a method for manufacturing a light emitting device, including:

depositing a film on a glass substrate containing indium tin oxide as an anode by a vacuum evaporation method under the vacuum degree of 1 multiplied by 10 < -5 > Pa;

co-evaporating a P-type dopant and a hole transport layer on a glass substrate according to the proportion of 1:1 to form a 10 nm-thick hole injection layer, wherein the P-type dopant is P-dopant, and the hole transport layer is HTL;

evaporating a hole input material with the thickness of 50nm on the hole injection layer to play a role as a hole transport layer;

an electron blocking layer with the thickness of 5nm is vapor-plated on the hole transport layer;

the host compound and the guest compound were co-deposited on the electron blocking layer to form an organic compound layer having a thickness of 35 nm. The host compound is BH, the concentration of BH is 97%, the guest compound is BD, and the concentration of BD is 3%;

an electron transport material and a photoelectric material are co-evaporated on the organic compound layer, the thickness of the film is 30nm, the film can be used as an electron transport layer to play a function, and the electron transport layer is ET;

an electron material is vapor-plated on the electron transport layer to form an electron injection layer with the thickness of 1 nm;

evaporating metal magnesium and metal silver on the electron injection layer film together, wherein the ratio of the metal magnesium to the metal silver is 8:2, and forming a metal cathode with the film thickness of 15 nm;

a compound was vacuum-deposited on the cathode as a light extraction layer to a thickness of 50 nm.

One of ordinary skill in the art can perform the processing according to the above-described operation steps to obtain the light emitting device.

Three different guest compounds, namely BD01, BD02 and BD03, were used in the disclosed embodiments, and three light-emitting devices were prepared by the above-described preparation method, and were tested, respectively, and the experimental data obtained are shown in fig. 6 to 8; and the molecular structural formulas of three different guest compounds BD01, BD02 and BD03 are shown in FIG. 6; specific parameters for the three different materials are given in the table below,

Materials	L	S	L/S	Orientation	EQE
						BD01	14.11	13.76	1.03	84％	5.83
BD02	21.72	11.42	1.90	86％	6.07
						BD03	25.06	9.63	2.60	92％	6.42

in the above table, Orientation is expressed as the Orientation of the molecules and EQE is expressed as the external quantum efficiency. As can be seen from the above table, as the L/S ratio increases, the external quantum efficiency and the molecular orientation also increase, so that the light-emitting device has better light-emitting performance and higher light-emitting efficiency.

Referring to fig. 6 to 8, there are shown graphs showing that the molecular orientation of the light-emitting material in the light-emitting layer is derived by means of simulation by measuring the angle dependence of the integrated intensity of the obtained p-polarized emission spectrum of wavelengths from the visible light region to the near infrared region (440nm to 956nm) by polarizing the light-emitting line extracted from the light-emitting layer to extract the p-polarized light-emitting component, and analyzing the result by calculation. According to experimental data, the luminous intensity changes with the change of the angle, the molecule has angle dependence, and when the ratio of L and S reaches a certain value, a better molecular orientation is obtained, and the figure can evaluate how well the orientation is according to the experimental value. Specifically, it can be seen from experimental data that the parameter settings provided in the examples of the present disclosure have a clear relationship with the molecular orientation of the compound, and when L/S is greater than 1.5, the molecular orientation becomes good. Further, when L/S is greater than 1.8, the light extraction efficiency can be improved by controlling the orientation state of the molecules, and the light emitting performance of the light emitting device is further improved.

The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications and changes to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.