TWI612047B - Organic electron transport materials - Google Patents

Abstract

The present invention relates to an organic electron transport material, a compound having the structure described in formula (I), wherein R is a C1-C8 alkyl group, or a C2-C8 substituted or unsubstituted alkenyl group, or a C2-C8 substituted or Unsubstituted alkynyl; Ar ₁ and Ar _{2 are} independently represented as C6-C60 substituted or unsubstituted aryl. Device experiments show that only the organic organic semiconductor diode device and the organic electroluminescent device prepared by using the organic electron transport material of the present invention emit blue light, the electron transmission rate is high, the electron transmission performance is good, and the luminous efficiency is high. (I)

Description

Organic electron transport material

The invention relates to a novel organic electron transport material, which is formed into a thin film by vacuum deposition, and is used as an electron transport material for an electron-only organic semiconductor diode device.

An electronic-only organic semiconductor diode device is a type of single carrier device, and is used as a switch or rectifier for a smart digital power integrated circuit as a power semiconductor device. The electron transport material of the present invention can also be applied to organic electroluminescent devices and field effect transistors.

An electronic-only organic semiconductor diode device is a device prepared by spin-coating or depositing one or more organic materials between two electrodes of a metal, an inorganic substance, or an organic compound. A classic one-layer electronic-only organic semiconductor diode device includes an anode, an electron transport layer, and a cathode. A hole blocking layer may be added between the anode and the electron transport layer of the multilayer electron-only organic semiconductor diode device, and an electron injection layer may be added between the electron transport layer and the cathode. The hole blocking layer, the electron transporting layer and the electron injection layer are respectively composed of a hole blocking material, an electron transporting material and an electron injection material. After the voltage connected to the electron-only organic semiconductor diode device reaches the turn-on voltage, electrons generated by the cathode are transferred to the anode through the electron transport layer, and conversely, holes cannot be injected from the anode. Only the electron-transporting material in the electronic organic semiconductor diode device can be applied to other semiconductor devices such as an electroluminescent device. Organic electroluminescence devices have a huge market. Therefore, stable and efficient organic electron transport materials play an important role in the application and promotion of organic electroluminescence devices, and they are also an urgent need for the application and promotion of organic electroluminescence large-area panel displays.

分子結構的鏡面用虛線表示Many of the currently used electron transport materials on the market, such as red phenanthroline (BPhen) and bath copper (BCP), can basically meet the market demand for organic electroluminescent panels, but their efficiency and stability There is still room for further improvement. From the analysis of the molecular structure of BPhen and BCP, the symmetrical structure will make the molecules tend to be stacked regularly, and it is easy to be crystallized after time. Once the electron transport material is crystallized, the charge transition mechanism between the molecules is not the same as that of the amorphous film in normal operation, resulting in a change in the electron transport performance. If materials with BPhen symmetrical molecular structure are used in organic electroluminescence devices, the conductivity of the entire device will change after time passes, and the electron and hole charge mobility will be unbalanced, resulting in a decrease in the device's efficiency and may also cause localization in the device. Short circuit affects the stability of the device and even causes the device to fail.

The mirror surface of the molecular structure is indicated by a dotted line

In view of the defects of the above materials, the present invention provides an organic electron transport material that can be applied to long-life electronic-only organic semiconductor diode devices and organic electroluminescence devices with high electron transmission rate, good electron transmission performance, and high luminous efficiency.

（I）An organic electron transporting material, a compound having a structure of formula (I),

(I)

Wherein, R is C1-C8 alkyl, or C2-C8 substituted or unsubstituted alkenyl, or C2-C8 substituted or unsubstituted alkynyl; wherein Ar ₁ and Ar _{2 are} independently represented as C6- C60 substituted or unsubstituted aryl.

Preferably: wherein R is a C1-C4 alkyl group, or a C2-C4 substituted or unsubstituted alkenyl group, or a C2-C4 substituted or unsubstituted alkynyl group; wherein Ar ₁ and Ar _{2 are} independently represented as C1-C4 alkyl or C6-C30 aryl substituted or unsubstituted phenyl, naphthyl, anthracenyl, phenanthryl, fluorenyl, fluorenyl, fluoranthenyl, (9,9-dialkyl) fluorenyl , (9,9-dialkyl substituted or unsubstituted aryl) fluorenyl or 9,9-spirofluorenyl.

Preferably: wherein R is preferably represented by methyl, ethyl, propyl, isopropyl; wherein Ar ₁ and Ar _{2 are} independently represented by phenyl, tolyl, xylyl, naphthyl, methylnaphthalene, biphenyl Phenyl, diphenylphenyl, naphthylphenyl, diphenylbiphenyl, (9,9-dialkyl) fluorenyl, (9,9-dimethyl substituted or unsubstituted phenyl) fluorenyl , 9,9-spirofluorenyl.

。 優選：R優選為甲基。 優選：Ar₁ 、Ar₂ 相同。 更優選：式（I）所述的化合物為下列結構化合物

。As mentioned above, the compounds of formula (I) of the present invention are as follows, but are not limited to the enumerated structures:

. Preferably: R is preferably methyl. Preferably, Ar ₁ and Ar _{2 are the} same. More preferably: the compound of formula (I) is a compound of the following structure

.

An electron-only organic semiconductor diode device includes an anode, a cathode, and an organic layer. The anode and the cathode are a metal, an inorganic substance, or an organic compound. The organic layer is a hole blocking layer, an electron transport layer, or an electron injection layer. One or more layers. It should be particularly pointed out that the above-mentioned organic layers can be according to requirements, and these organic layers do not need to exist in each layer.

The hole blocking layer, the electron transport layer, and / or the electron injection layer contain a compound represented by the formula (I). The compound of the formula (I) is an electron transporting material.

The total thickness of the organic layer of the electronic device of the present invention is 1-1000 nm, preferably 1-500 nm, and more preferably 5-300 nm.

The organic layer may be formed into a thin film by evaporation or spin coating.

Device experiments show that only the organic organic semiconductor diode device and the organic electroluminescent device prepared by using the organic electron transport material of the present invention emit blue, high electron transmission rate, good electron transmission performance, and high luminous efficiency.

In order to describe the present invention in more detail, the following examples are given, but are not limited thereto.

化合物4 的合成 反應投放：向反應瓶中加入4,7-二苯基菲羅啉(5.0g, 15mmol)，充放氮氣三次後加入無水THF(180 mL)，冰水浴降溫15分鐘後在反應混合物中加入甲基鋰正己烷溶液(12ml, 15.07mmol)，反應液由開始的白色濁狀液逐漸變為藍黑色，直至黑色，加入溶液後室溫攪拌8h，然後在空氣中攪拌24h。停止反應後，旋乾THF，加入水(100 mL)和二氯甲烷(150 mL x 3)萃取，有機層合併，用無水硫酸鎂乾燥後過濾，濾液旋乾後用丙酮(50mL)打漿，抽濾，濾質為化合物4 (5.19克, 99%)。真空(4 x 10^-5 torr) 加熱160^o C昇華完成後得到3.14克黃色粉末狀產品，純度99.575%，見圖1，峰值統計見下表。¹ H NMR (300 MHz, CDCl₃ ) δ 9.21 (d,J = 3 Hz, 1H), 7.76 (s, 2H), 7.52 – 7.46 (m, 12H);¹³ C NMR (75 MHz, CDCl₃ ) δ 159.0, 149.8, 148.6, 148.5, 146.7, 146.5, 138.2, 129.8, 129.8, 128.7, 128.5, 128.5, 126.6, 124.7, 124.3, 124.1, 123.4, 123.1, 26.3。 峰表 PDA Ch1 254nm

液相的條件如下： 色譜柱：InertSustain C18 4.6*250 mm，5μm,柱溫：40℃ 溶劑：DCM, 流動相：MeOH:4mMNa2EDTA水溶液=8:2,檢測波長：254nm 其氫譜、碳譜和TGA圖見圖2－4。Example 1

Synthesis reaction of compound 4 : Add 4,7-diphenylphenanthroline (5.0 g, 15 mmol) to the reaction flask, fill with nitrogen for three times, and then add anhydrous THF (180 mL). After cooling in an ice-water bath for 15 minutes, react Methyl lithium n-hexane solution (12 ml, 15.07 mmol) was added to the mixture, and the reaction liquid gradually changed from the initial white turbid liquid to blue-black to black. After the solution was added, the mixture was stirred at room temperature for 8 hours, and then stirred in air for 24 hours. After the reaction was stopped, THF was spin-dried, water (100 mL) and dichloromethane (150 mL x 3) were added for extraction. The organic layers were combined, dried over anhydrous magnesium sulfate, and filtered. The filtrate was spin-dried and slurried with acetone (50 mL). Filtration with the compound 4 (5.19 g, 99%). After vacuum (4 x 10 ^-5 torr) heating at 160 ^o C, 3.14 g of yellow powdery product was obtained with a purity of 99.575%, as shown in Figure 1. The peak statistics are shown in the table below. ¹ H NMR (300 MHz, CDCl ₃ ) δ 9.21 (d, J = 3 Hz, 1H), 7.76 (s, 2H), 7.52 – 7.46 (m, 12H); ¹³ C NMR (75 MHz, CDCl ₃ ) δ 159.0, 149.8, 148.6, 148.5, 146.7, 146.5, 138.2, 129.8, 129.8, 128.7, 128.5, 128.5, 126.6, 124.7, 124.3, 124.1, 123.4, 123.1, 26.3. Peak Table PDA Ch1 254nm

The conditions of the liquid phase are as follows: Column: InertSustain C18 4.6 * 250 mm, 5 μm, column temperature: 40 ° C Solvent: DCM, mobile phase: MeOH: 4mM Na2EDTA aqueous solution = 8: 2, detection wavelength: 254nm The TGA chart is shown in Figure 2-4.

（1） 其中，J為電流密度（mA cm^-2 ）,ε為相對介電常數（有機材料通常取值為3）， ε₀ 為真空介電常數（8.85×10^-14 C V^-1 cm^-1 ）， E為電場強度（V cm^-1 ），L為器件中樣本的厚度（cm），μ₀ 為零電場下的電荷遷移率（cm² V^-1 s^-1 ），β為Poole–Frenkel 因數，表示遷移率隨電場強度變化的快慢程度。 所製備的器件在E = 1 x 10⁶ Vcm^-1 的工作電場下的電子遷移率為2.36 x 10^-4 cm² V^-1 s^-1 。 器件中所述結構式

Example 2: Preparation of an electronic-only organic semiconductor diode device 1 An organic-only organic semiconductor diode device was prepared using the organic electron transport material of the present invention, as shown in FIG. 5. First, the transparent conductive ITO glass substrate 10 (with the anode 20 on it) is sequentially passed through: detergent solution and deionized water, ethanol, acetone, deionized water, and then treated with oxygen plasma for 30 seconds. Then, 5 nm thick BCP was evaporated on the ITO as the hole blocking layer 30. Then, 100 nm thick compound 4 was evaporated as an electron transport layer 40 on the hole blocking layer. Then, 1 nm thick lithium fluoride was evaporated on the electron transport layer as the electron injection layer 50. Finally, 100 nm thick aluminum was evaporated on the electron injection layer as the device cathode 60. By using space charge limited current (SCLC), the relationship between the current density and the electric field strength is as shown in equation (1):

(1) wherein, J is the current density (mA cm ^-2), ε is the relative dielectric constant (a value of the organic material typically 3), ε ₀ is the permittivity of vacuum ^{(8.85 × 10 -14 CV -1 cm} - ¹ ), E is the electric field strength (V cm ^-1 ), L is the thickness of the sample in the device (cm), μ ₀ is the charge mobility (cm ² V ^-1 s ^-1 ) at zero electric field, and β is Poole– Frenkel factor, which indicates how fast the mobility changes with the strength of the electric field. The device produced in E = electron mobility under operating electric field of 1 x 10 ⁶ Vcm ^-1 rate of ^{2.36 x 10 -4 cm 2 V -1} s -1. Structure described in the device

Comparative Example 1: The preparation method of the electronic-only organic semiconductor diode device 2 is the same as that of Example 2, but a commonly-used commercially available compound TmPyPB is used as the electron transporting layer 40 to produce an electronic-only organic semiconductor diode device for comparison. The device produced in E = electron mobility under operating electric field of 1 x 10 ⁶ Vcm ^-1 rate of ^{1.61 x 10 -6 cm 2 V -1} s -1. Structure described in the device

Comparative Example 2: The preparation method of the electron-only organic semiconductor diode device 3 is the same as that of Example 2, but using the compound PhBPhen (synthesized according to US20080265746) as the electron transport layer 40, an electron-only organic semiconductor diode device for comparison is produced. The device produced in E = electron mobility under operating electric field of 1 x 10 ⁶ Vcm ^-1 rate of ^{8.12 x 10 -4 cm 2 V -1} s -1. Structure described in the device

As shown in Figures 6 to 9, the prepared device has a voltage of 3.75V at a working current density of 20mA / cm ² and a current efficiency of 2.93.cd/A. At a brightness of 1000cd / m ² , the CIEy coordinate is 0.0915. Blu-ray.

From the comparison of device data, from the voltage and current density curve, the first one has the highest electron transmission rate, the second one is the second, and the third one is worse, that is, the electron transmission performance is the best. In terms of current density-current efficiency, the luminous efficiency of the device 1 is high. The brightness and color coordinates look similar to device 1, device 2 and device 3, indicating that the chromaticity changes of several materials are basically the same, and the spectral data shows that the energy level difference between HOMO and LUMO is the same.

10‧‧‧ glass substrate
20‧‧‧Anode
30‧‧‧ hole transport layer
40‧‧‧ electron transmission layer
50‧‧‧ electron injection layer
60‧‧‧ cathode

Figure 1 is an HPLC chart of the compound of Example 1; Figure 2 is a carbon spectrum of the compound of Example 1; Figure 3 is a hydrogen spectrum of the compound of Example 1; Figure 4 is a TGA chart of the compound of Example 1; The device structure diagram of the invention, where 10 represents a glass substrate, 20 represents an anode, 30 represents a hole blocking layer, 40 represents an electron transport layer, 50 represents an electron injection layer, and 60 represents a cathode; FIG. 6 shows the invention Voltage-current density diagrams of Example 2 (device 1) and Comparative Examples 1 and 2 (devices 2 and 3); FIG. 7 shows Example 2 (device 1) and comparative examples 1 and 2 (devices 2 and 3) of the present invention. ) Current density-current efficiency graph; FIG. 8 is a luminance-color coordinate y diagram of Example 2 (device 1) and Comparative Examples 1 and 2 (devices 2 and 3) of the present invention; and FIG. 9 is an implementation of the present invention Emission spectrum diagrams of Example 2 (device 1) and Comparative Examples 1 and 2 (devices 2 and 3).

Claims (6)

An organic electron transport material, a compound having a structure described by formula (I),

Among them, R represents methyl; Ar ₁ and Ar _{2 are} independently represented by phenyl, naphthyl, anthryl, phenanthryl, fluorenyl, fluorenyl, fluorenyl, fluorenyl, fluorenyl, or phenyl substituted with C1-C4 alkyl or C6-C30 aryl. Group, fluoranthenyl, (9,9-dialkyl) fluorenyl, (9,9-dialkyl substituted or unsubstituted aryl) fluorenyl, or 9,9-spirofluorenyl. The organic electron transporting material according to item 1 of the scope of patent application, wherein R is a methyl group, and Ar ₁ and Ar _{2 are} independently phenyl, tolyl, xylyl, naphthyl, methylnaphthalene, and Phenyl, diphenylphenyl, naphthylphenyl, diphenylbiphenyl, (9,9-dialkyl) fluorenyl, (9,9-dimethyl substituted or unsubstituted phenyl) fluorenyl , 9,9-spirofluorenyl. The organic electron transport material as described in the first patent application scope, its structural formula is as follows:

The organic electron-transporting material according to item 2 of the scope of patent application, wherein Ar ₁ and Ar _{2 are the} same. The organic electron transport material as described in item 4 of the scope of patent application, its structural formula is as follows:

The organic electron transport material according to any one of claims 1 to 5 in the scope of application for a patent, wherein the organic electron transport material is used in an electronic-only organic semiconductor diode device.