Organic light emitting diodes of derivative phosphorescent materials containing boron pentafluoride units

Abstract

The invention discloses an organic light-emitting diode of a derivative phosphorescent material containing a boron pentafluoride unit. At present, although many RTP materials are explored, OLED phosphorescent materials with high luminescence and high performance are still scarce, which limits the development of electroluminescent devices to a certain extent. According to the invention, a series of boron pentafluoride compounds are synthesized from malonyl chloride as a raw material, and the compounds show very good phosphorescent properties. Meanwhile, when the compound is applied to an electroluminescent device structure, the mobility of holes and electrons can be well balanced, so that the problem that the mobility of carriers is unbalanced is well solved. The material can be used as a novel photoelectric material and has applicability in the fields of OLED and the like.

Description

Technical Field

[0001] The present invention belongs to the field of organic photoelectric materials. Specifically, we design and synthesize a type of derivative phosphorescent materials containing boron pentafluoride units, and apply them in the structure of organic light emitting diode (OLED) light emitting devices. Background Art

[0002] Pure organic room temperature phosphorescence (RTP) has the advantages of low cost, good biocompatibility and convenient preparation, and is widely used in organic light-emitting diodes (OLEDs), time-gated bioimaging, anti-counterfeiting and sensors. As a new display and lighting technology, organic light-emitting diodes (OLEDs) have attracted widespread attention from academia and industry due to their advantages such as self-luminescence, low power consumption, fast response, wide color gamut and flexible display. In recent years, in order to solve the limitation of traditional fluorescent materials using excitons with an internal quantum efficiency of 25%, it is urgent to develop a new generation of organic light-emitting materials that can make full use of triplet states. Phosphorescent materials have become a research hotspot because they can theoretically completely capture the luminescence of triplet excitons. Traditional phosphorescent materials contain rare metal elements (Ir, Pt), which inevitably lead to environmental pollution and high costs in industrial production. RTP materials make up for this shortcoming due to their own characteristics, thus greatly promoting the development of OLEDs. At present, although many RTP materials have been discovered, OLED phosphorescent materials with high luminescence and high performance are still scarce. Therefore, it is of great significance to develop OLED organic phosphorescent materials with high luminescence and high performance and apply them in the structure of organic light emitting diode (OLED) light emitting devices. Summary of the invention

[0003] The present invention belongs to the field of organic photoelectric materials. Specifically, we design and synthesize a type of derivative phosphorescent materials containing boron pentafluoride units, and apply them in the structure of organic light emitting diode (OLED) light emitting devices.

[0004] The purpose of the present invention is to develop an OLED organic phosphorescent material with high luminescence and high performance, and apply it to the structure of an organic light-emitting diode (OLED) light-emitting device. According to literature reports, the connection of pentafluorophenyl groups with small molecule p-type organic semiconductors can produce bipolar or n-type organic semiconductors. At the same time, compounds introducing pentafluorophenyl groups can largely balance the carrier mobility of electroluminescent devices. At present, most of the compounds introducing pentafluorophenyl groups are introduced into planar compounds such as perylene and anthracene, and have obvious planarity in the molecular structure. Although they have high luminescence efficiency, most of these compounds have fluorescent properties. This limits the efficiency of electroluminescent devices to a certain extent. We envision designing and synthesizing boron pentafluoride molecules containing donor-acceptor (DA) structures with certain twisted structures and high luminescence characteristics in molecular structures, thereby showing different photophysical and photochemical properties, such as RTP properties. And apply them in OLEDs to achieve high-performance electroluminescent devices. At the same time, the synthesis of boron pentafluoride molecules and the preparation of OLED devices can provide certain inspiration for the device structure design of OLED, and can continuously expand the types and quantities of new OLED phosphorescent compounds, laying a more solid molecular foundation for electroluminescent devices.

[0005] The present invention belongs to the field of organic optoelectronic materials. Specifically, we designed and synthesized a class of derivative phosphorescent materials containing boron pentafluoride units, and prepared OLED light-emitting devices of the materials. First, we purchased malonyl chloride, and then accessed different electron-donating groups through Horner-Wadsworth-Emmons coupling reaction. Then, pentafluorophenyl was introduced through borylation reaction, and finally a series of boron pentafluoride compounds were synthesized and applied in the structure of electroluminescent devices. It is worth noting that theoretically all hydrogen-nitrogen heterocyclic compounds can react. We confirmed the correctness of our compound synthesis by means of mass spectrometry, nuclear magnetic resonance, single crystal analysis, etc. It can be concluded through crystal structure analysis and theoretical calculation that this type of compound has an obvious twisted structure and a high luminescence efficiency, which lays a very good molecular structure foundation for achieving balanced carrier mobility of electroluminescent devices. At the same time, it can be seen through electrical testing that after the introduction of pentafluorophenyl, the hole and electron mobility of the electroluminescent device are well balanced under the premise of maintaining high luminescence efficiency. Therefore, it is particularly important to study its internal mechanism for better application in OLED, which is also a content of our future research. In summary, this type of compound is a very good organic optoelectronic material.

[0006] It should be understood that the advantages of the present invention will be described in the following description, and the following detailed description is exemplary and explanatory. The purpose and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required in the description of the embodiments:

[0008] Figure 1 It is the general formula for the synthesis of boron pentafluoride compounds in Example 1 of the present invention. In the first step, malonyl chloride (0.15ml 1.5mmol) and a nitrogen-containing compound (3mol) are placed in a 10mL branch tube reactor, and then 20mL tetrahydrofuran is added under nitrogen protection, and the reaction is carried out at room temperature overnight. The product is obtained by silica gel column separation. Then, the product obtained in the first step (1mmol) and tris(pentafluorophenyl)borane (0.61g, 1.2mmol) are placed in a 100ml branch tube reactor, and then 10ml toluene is added under nitrogen protection, and the reaction is carried out at 110°C overnight. The final product is obtained by silica gel column separation.

[0009] Figure 2 Embodiment 1 of the present invention is Figure 1 Nine different boron pentafluoride derivatives were obtained by changing different nitrogen-containing compounds, and their molecular formulas are listed in the figure.

[0010] Figure 3 The shape and luminescent color of the crystal of compound 1 under 365nm ultraviolet light are shown in Example 1 of the present invention. It can be seen that the compound emits green light under 365nm ultraviolet light and has a high luminescent efficiency.

[0011] Figure 4 The photophysical test data of Example 1 of the present invention is shown in Figure 1, taking Compound 1 as an example. It can be seen from the lifetime decay curve, delay spectrum and temperature-dependent spectrum that this type of compound is a very good phosphorescent material.

[0012] Figure 5 This is a single crystal diagram of compound 1 in Example 1 of the present invention. It can be seen that this type of compound has a certain degree of distortion.

[0013] Figure 6 In Example 1 of the present invention, taking compound 1 as an example, the highest occupied orbital (HOMO) and the lowest occupied orbital (LUOM) of the evaporated film of boron pentafluoride compound are measured by cyclic voltammetry. It can be seen that the HOMO and LUOM energy levels of boron pentafluoride are conducive to the injection of electrons and holes.

[0014] Figure 7Taking compound 1 as an example in Example 1 of the present invention, it can be seen from the current density-voltage characteristic curve (JV curve) that after the introduction of boron pentafluoride, the electron mobility and the hole mobility are well balanced, thereby improving the carrier mobility. DETAILED DESCRIPTION

[0015] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve the technical problems raised in previous years and achieve the technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various features in the various embodiments of the present invention can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0016] The invention discloses the synthesis and application of a class of derivatives containing boron pentafluoride units.

[0017] Through design and modification, a series of derivatives containing boron pentafluoride units were synthesized.

[0018] Derivatives containing boron pentafluoride units have the advantages of simple synthesis steps, cheap and readily available raw materials, simple purification methods, high yields, and high fluorescence quantum yields.

[0019] The derivatives containing boron pentafluoride units have higher solid fluorescence quantum yield.

[0020] The derivatives containing BF5 units have a certain degree of distorted structure.

[0021] Derivatives containing boron pentafluoride units are a class of electroluminescent device materials with balanced carrier mobility.

[0022] Embodiment 1:

[0023] Figure 1 As shown, in the first step, malonyl chloride (0.15ml 1.5mmol) and a nitrogen-containing compound (3mol) were placed in a 10mL branch tube reactor, and then 20mL tetrahydrofuran was added under nitrogen protection, and the reaction was carried out at room temperature overnight. The product was obtained by separation through a silica gel column. Then, the product obtained in the first step (1mmol) and tris(pentafluorophenyl)borane (0.61g, 1.2mmol) were placed in a 100ml branch tube reactor, and then 10ml toluene was added under nitrogen protection, and the reaction was carried out at 110°C overnight. The final product was obtained by separation through a silica gel column.

[0024] Embodiment 2:

[0025] Figure 2 The nine compounds shown in the figure were obtained by changing different nitrogen heterocyclic compounds. It is worth noting that all hydrogen-containing nitrogen heterocyclic compounds can be connected.

[0026] Embodiment three:

[0027] Figure 3 Taking compound 1 as an example, we cultured the crystals of compound 1 and irradiated it under 365nm ultraviolet light. We found that the crystals emitted bright green light, indicating that this type of compound has a high luminescence efficiency.

[0028] Embodiment 4:

[0029] Figure 4 Taking compound 1 as an example, we used the cultured crystals to test the photophysical properties. Through the temperature-dependent lifetime decay graph, temperature-dependent spectrum and temperature-dependent delay spectrum, we can conclude that this type of crystal has good phosphorescence properties. This provides a good material basis for better application in electroluminescent devices.

[0030] Embodiment five:

[0031] Figure 5 Taking compound 1 as an example, we analyzed the single crystal of the prepared compound 1 and confirmed that this type of compound has a certain degree of twisted structure, which confirmed the rationality and feasibility of the design.

[0032] Embodiment six:

[0033] Figure 6 Taking compound 1 as an example, the HOMO and LUMO energy levels obtained by cyclic voltammetry test were examined. It can be seen that the HOMO and LUMO energy levels of boron pentafluoride are conducive to the injection of electrons and holes. The same properties were obtained by examining its boron pentafluoride compounds, indicating that this type of boron pentafluoride can well balance the carrier mobility in electrochemical devices.

[0034] Embodiment seven:

[0035] Figure 7 The electroluminescent device test of the material. First, a pure evaporated film of boron pentafluoride was prepared, and then the following electroluminescent device structure was prepared: HOD:ITO(180nm) / PEDOT:PSS(40nm) / ArBFO(80nm) / C60(3nm) / Mo03(10nm) / A1(100nm)EOD:A1(100nm) / LiF(1) / ArBFO(80nm) / TPBi(4nm) / A1(100nm). The JV curve was obtained through electrical testing. We can conclude that the hole and electron mobility of boron pentafluoride compounds are well balanced, which improves the carrier mobility, indicating that this type of compound has good application potential in electroluminescent devices.

Claims

1. Organic light-emitting diodes containing phosphorescent materials derived from boron pentafluoride units.

2. The derivative containing boron pentafluoride units according to claim 1, characterized in that: A series of compounds containing boron pentafluoride units were designed and synthesized. These compounds have the characteristics of low-cost raw materials, simple synthesis, and easy purification.

3. The derivative containing boron pentafluoride unit according to claim 3, characterized in that: It has high luminous efficiency and can effectively improve the external quantum efficiency of electroluminescent devices when used in their structure.

4. The derivative containing boron pentafluoride units according to claim 3, characterized in that: It has very good phosphorescent properties and can make good use of 75% triplet excitons in electroluminescent devices, thereby improving the external quantum efficiency of electroluminescent devices.

5. The derivative containing boron pentafluoride units according to claim 4, characterized in that: There is a certain degree of distortion in its molecular structure, which is conducive to the emission of phosphorescence.

6. The derivative containing boron pentafluoride units according to claim 5, characterized in that: Its HOMO and LUMO energy levels are conducive to the injection of holes and electrons and can be applied in the research of electroluminescent devices.

7. The derivative containing a boron pentafluoride unit according to claim 6, characterized in that: The prepared electro-induced device has balanced carrier mobility, and can well improve the problem of unbalanced carrier mobility in the electro-induced device.

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