Small molecule photocrosslinking agent, preparation method and application

Abstract

The application discloses a small-molecule photo-crosslinking agent, a preparation method and application thereof, and belongs to the field of organic semiconductors. The structural formula of the small-molecule photo-crosslinking agent is shown as formula I: the preparation method comprises the following steps: reducing aldehyde groups in tri(4-formylphenyl)amine into benzyl alcohol to generate tribenzyl alcohol amine; under alkaline conditions, hydroxyl groups in the tribenzyl alcohol amine are converted into azide groups through a nucleophilic aromatic substitution reaction to generate a compound shown as formula I. The small-molecule photo-crosslinking agent has UV photo-crosslinking characteristics, can be used for ultraviolet photoetching patterning of solution-processed polymer semiconductors, is simple to synthesize, safe and efficient, and has the potential for large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of organic semiconductors, and particularly relates to a small-molecule photo-crosslinking agent with UV photo-crosslinking characteristics and a preparation method and application thereof. BACKGROUND

[0002] Organic semiconductor materials have important applications in organic light-emitting diodes (OLEDs) and field effect transistors (OFETs) due to their advantages such as solution processing, adjustable structure, and flexibility and thinness. Realizing micro-nano manufacturing and multi-functional integration of organic semiconductor devices is a key to the transition from laboratory to industrial application. Photolithography is a core step in large-scale and high-precision manufacturing of integrated circuits and micro-nano semiconductor components, and is an important way to realize miniaturization and integration of electronic devices. However, organic semiconductor materials themselves do not have photolithography performance, and small-molecule photo-crosslinking agents need to be added. However, the commonly used photo-crosslinking groups still have many limitations, such as byproduct residues, poor material compatibility, and low photo-crosslinking reaction activity. Therefore, it is urgent to develop more efficient photo-crosslinking materials that are better compatible with organic semiconductor materials.

[0003] Azido groups have high photosensitivity, fast reaction speed, and no byproduct residues, and are expected to provide a new solution for high-precision direct photolithography patterning manufacturing and multi-functional high-density integration of micro-nano organic semiconductors. However, existing azido-type crosslinking small molecules are all based on pentafluorobenzoic acid as a basic building unit, and the structure is single. In addition, sodium azide (explosive) is used in the synthesis process, and the reaction conditions are strict and dangerous. Therefore, it is urgent to develop safer, more efficient, and better compatible azido-type small-molecule photo-crosslinking agents for organic semiconductors. SUMMARY

[0004] The purpose of the present application is to provide a small-molecule photo-crosslinking agent with UV photo-crosslinking characteristics and a preparation method and application thereof. Triphenylamine is used as a molecular skeleton, and an azido substituent group is introduced as a photo-crosslinking site. The small-molecule photo-crosslinking agent can be added to a semiconductor thin film to realize direct photolithography patterning of a solution-processed semiconductor thin film.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a small-molecule photo-crosslinking agent with UV photo-crosslinking characteristics. The core structure is triphenylamine, and the benzene ring contains an azido substituent group. The structural formula is shown as formula I:

[0007]

[0008] Formula I.

[0009] In a second aspect, the present application provides a preparation method of the small molecule photo-crosslinking agent shown in the above formula I, comprising the following steps:

[0010] The aldehyde group in the tri (4-formylphenyl) amine is reduced to benzyl alcohol to generate triphenylcarbinol amine;

[0011] The hydroxyl group in the triphenylcarbinol amine is converted into an azide group under alkaline conditions through a nucleophilic aromatic substitution reaction to generate the compound shown in the formula I.

[0012] Further, in the preparation method, the reducing agent used for reducing the aldehyde group in the tri (4-formylphenyl) amine to benzyl alcohol is sodium borohydride, the reaction solvent is a mixed solution of anhydrous ethanol and anhydrous tetrahydrofuran, and the reaction temperature is 40 DEG C.

[0013] Further, in the preparation method, in the conversion of the hydroxyl group in the triphenylcarbinol amine into an azide group, the azide reagent used is diphenyl phosphorazide, and the molar ratio of diphenyl phosphorazide to triphenylcarbinol amine is 2-10:1.

[0014] Further, in the preparation method, in the conversion of the hydroxyl group in the triphenylcarbinol amine into an azide group, the alkaline substance used is 1,8-diazobicyclo[5.4.0]undec-7-ene, the reaction solvent is anhydrous tetrahydrofuran, the reaction temperature is 40 DEG C, and the reaction time is 48 hours.

[0015] The present application also provides an application of the small molecule photo-crosslinking agent shown in the above formula I in the crosslinking of a polymer thin film.

[0016] The polymer includes a conjugated polymer and a non-conjugated polymer.

[0017] The present application also provides an application of the small molecule photo-crosslinking agent shown in the above formula I in the photoetching patterning of a solution-processed semiconductor thin film.

[0018] The solution-processed semiconductor includes an organic semiconductor, a quantum dot and a perovskite material.

[0019] The present application also provides an application of the small molecule photo-crosslinking agent shown in the above formula I in the preparation of an organic semiconductor device.

[0020] The organic semiconductor device includes an organic light-emitting diode, an organic field effect transistor, an organic solar cell, an organic integrated circuit, an organic thermoelectric device and the like.

[0021] Compared with the prior art, the technical scheme of the present application has the following beneficial technical effects:

[0022] 1. The raw materials used in the synthesis of the present application are convenient and easy to obtain, the preparation process is safer and more efficient, the conditions are mild, and the process is easy to be industrialized and mass-produced.

[0023] 2、The small molecule photo-crosslinking agent has excellent solution processing characteristics and better compatibility with solution-processed organic semiconductors.

[0024] 3、The small molecule photo-crosslinking agent has excellent UV photo-crosslinking characteristics, can realize direct photoetching patterning of semiconductor thin films, simplifies the photoetching process, and has no byproduct residue. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The H-NMR chart of the compound TPA-3X in the embodiment 1 of the present application is shown in Figure 1. 1 H-NMR chart;

[0026] Figure 2 The C-NMR chart of the compound TPA-3X in the embodiment 1 of the present application is shown in Figure 2. 13 C-NMR chart;

[0027] Figure 3 The high-resolution mass spectrum chart of the compound TPA-3X in the embodiment 1 of the present application is shown in Figure 3.

[0028] Figure 4 The thermogravimetric analysis chart of the compound TPA-3X in the embodiment 1 of the present application is shown in Figure 4.

[0029] Figure 5 The example chart of realizing high-precision photoetching patterning of polymer semiconductor thin films by using the compound TPA-3X in the embodiment 1 of the present application as a photo-crosslinking agent is shown in Figure 5.

[0030] Figure 6 The spectral property chart of the polymer semiconductor thin film before and after photoetching in the embodiment 2 of the present application is shown in Figure 6, (a) is an absorption spectrum chart, and (b) is an emission spectrum chart.

[0031] Figure 7 The example chart of realizing photoetching patterning of quantum dot light-emitting thin films by using the compound TPA-3X in the embodiment 1 of the present application as a photo-crosslinking agent is shown in Figure 7.

[0032] Figure 8 The structure schematic chart of the electroluminescent device prepared in the embodiment 4 of the present application is shown in Figure 8.

[0033] Figure 9 The performance test chart of the electroluminescent device prepared in the embodiment 4 of the present application is shown in Figure 9, (a) is a chart of current density and brightness changing with voltage, (b) is a chart of current efficiency changing with current density, and (c) is an electroluminescent spectrum chart of the device. DETAILED DESCRIPTION

[0034] The present application will be further described in conjunction with specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0035] It should be noted that the technical terms or scientific terms used in the present application should be understood as the general meaning understood by the skilled person in the field of the present application, unless otherwise stated. The raw materials, reagents, etc. can be obtained from public commercial channels, unless otherwise stated. Examples

[0036] The synthesis route of the compound (TAP-3X) shown in Formula I is as follows:

[0037] The preparation method comprises:

[0038] Step 1: Dissolve the reactant tris (4-formylphenyl) amine (TPA-3O) (0.8 g, 2.4 mmol) in 10 mL of anhydrous ethanol and 25 mL of anhydrous tetrahydrofuran, and fully stir to dissolve under ice bath conditions. Then, slowly add sodium borohydride (NaBH4) (0.55 g, 14.5 mmol), and gradually warm to 40°C, and fully react for 12 h. After the reaction is completed, add deionized water (100 mL) to the reaction bottle, and stir vigorously for 1 h to remove the excess sodium borohydride. Finally, extract the organic phase with dichloromethane and saturated brine, and after concentration, column chromatography, drying, etc., the product trisphenylcarbinolamine (TPA-3OH) is obtained.

[0039] Step 2: Dissolve the above product TPA-3OH (0.6 g, 1.8 mmol) in 30 mL of anhydrous tetrahydrofuran, and then add 1,8-diazobicyclo[5.4.0]undec-7-ene (DBU) (0.95 g, 6.3 mmol) and diphenyl phosphorazide (DPPA) (1.7 g, 6.3 mmol) in sequence, and react at 40°C for 48 h under nitrogen protection. After the reaction is completed, add about 10 mL of saturated sodium bicarbonate solution dropwise to the reaction bottle, and stir for 10 min. Finally, extract with dichloromethane and saturated brine, dry the organic phase with anhydrous sodium sulfate, and after vacuum distillation, column chromatography purification, and drying, the product TPA-3X (0.45 g, 75%) is obtained.

[0040] The structure confirmation data are shown in Figure 1 and Figure 2 1H-NMR (400 MHz, CDCl3) δ 7.21 (d, 6H), 7.09 (d, 6H), 4.31 (s, 6H); 13 C-NMR (101 MHz) δ 147.49, 130.09, 129.55, 124.36, 54.53.

[0041] High resolution mass spectrometry test is as follows:Figure 3 The molecular weight of TPA-3X (C21H19N10) is 411.1795.

[0042] Figure 4 From the thermal gravimetric analysis data of TPA-3X, it can be concluded that the azido group decomposes at about 215°C. Example

[0043] The compound TPA-3X based on Example I of the present application realizes the photolithographic patterning of a solution-processed polymer semiconductor thin film, and the specific steps include:

[0044] First, the polymer semiconductor material (Livilux ® SPG-01T, Sigma-Aldrich NO. 900441) is prepared into a 4 mg / mL toluene solution and stirred at 100°C, and before use, it is filtered with a 0.45 μm polyvinylidene fluoride filter head. At the same time, TPA-3X is prepared into a 4 mg / mL toluene solution and stirred at room temperature. Then, the polymer semiconductor solution and the TPA-3X crosslinking agent solution are mixed in a certain proportion to prepare a mixed solution with a mass fraction of 2 wt% of TPA-3X. After that, the mixed solution is spin-coated on a glass / silicon wafer substrate that has been cleaned in advance (1500 rpm, 60 s) to form a uniform light-emitting thin film for subsequent photolithographic processing.

[0045] During photolithographic processing, first, the thin film is transferred to the glove box for annealing treatment (100°C, 15 min). Then, the thin film is exposed to a high-precision mask plate (40 mW / cm 2 , 60 s) using a UV lamp (240 nm-400 nm), and the thin film is annealed again (100°C, 15 min) to make the crosslinking reaction more complete. Finally, the processed thin film is placed in chloroform for sufficient development (20 s), and after blowing dry the surface solvent with a nitrogen gun, the target pattern is presented, and a specific patterning example is shown in Figure 5 , combined with the thin film spectral data shown in Figure 6 , it is proved that the crosslinking agent does not destroy the optical properties of the polymer semiconductor thin film. Example

[0046] The compound TPA-3X based on Example 1 of the present application realizes the photolithographic patterning of a quantum dot thin film, and the specific steps include:

[0047] First, the quantum dot material was prepared into a 10 mg / mL chlorobenzene solution and stirred thoroughly at 100°C for 24 hours. Meanwhile, the TPA-3X was prepared into a 10 mg / mL chlorobenzene solution and stirred thoroughly at room temperature. Then, the quantum dot solution and the TPA-3X crosslinker solution were mixed in a certain proportion to prepare a mixed solution with a TPA-3X mass fraction of 5 wt%. After that, the mixed solution was spin-coated on a glass / silicon sheet substrate that had been cleaned in advance (1500 rpm, 60 s) to form a uniform light-emitting thin film for subsequent photolithography.

[0048] During photolithography, the thin film was first transferred into a glove box for annealing treatment (100°C, 15 min). Then, the thin film was exposed to light by a high-precision mask under a UV lamp (240 nm-400 nm) (30 mW / cm 2 , 20 s), and the thin film was annealed again (100°C, 15 min) to make the crosslinking reaction more complete. Finally, the treated thin film was developed in chloroform for a sufficient time (20 s), and the surface solvent was blown dry with a nitrogen gun to present the target pattern, as shown in the specific patterning example of Figure 7 Embodiment

[0049] Application of the polymer semiconductor thin film prepared based on the compound TPA-3X of Embodiment 1 of the application in an electroluminescent device, the specific steps are as follows:

[0050] (1) The indium tin oxide (ITO) conductive glass was cleaned with cleaning agent, ethanol, acetone, isopropanol and deionized water respectively, dried with a nitrogen gun and treated with a UV ozone cleaning machine for 10-15 min, and ITO was used as an anode.

[0051] (2) Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS) was spin-coated on the ITO substrate (3000 rpm, 60 s), and then annealed at 120°C in air for 15 min to obtain a hole injection layer with a thickness of about 40 nm.

[0052] (3) The solution containing TPA-3X with a mass fraction of 2 wt% prepared in Embodiment 2 was spin-coated on the PEDOT:PSS layer (1500 rpm, 60 s) to obtain a uniform thin film with a thickness of 50-70 nm. Then, the thin film was transferred into a glove box and annealed at 100°C for 15 min, and then exposed to light by a high-precision mask under a UV lamp (240 nm-400 nm) (40 mW / cm 2 , 60 s) to initiate the crosslinking reaction.

[0053] ​(4) Finally, the film was transferred to a thermal evaporation chamber, and 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi), lithium fluoride (LiF) and aluminum (Al) electrodes were sequentially deposited under a vacuum of 1 × 10 -5 -6 Pa to obtain a polymer electroluminescent device with an effective light-emitting area of 4 mm 2 2, and the structure of the obtained device is shown in Figure 8 .

[0054] After testing, the performance curve of the prepared device is shown in Figure 9 , wherein the maximum brightness of the polymer electroluminescent device prepared based on the original film is 13000 cd m -2 -2, the maximum current efficiency is 2.0 cd A -1 , the maximum brightness of the device prepared from the film added with the photocrosslinking agent TPA-3X (2 wt%) and subjected to exposure crosslinking is 5200 cd m -2 -2, and the maximum current efficiency is 1.6 cd A -1 -2. In addition, the peak values of the electroluminescent spectra of the devices based on the two films are both at 500 nm. It can be seen that after the photocrosslinking agent is added and subjected to ultraviolet exposure, the luminous brightness of the device is reduced, but the color purity of the light emission is not affected.

[0055] The above has disclosed the present application with preferred embodiments, but it is not intended to limit the present application, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A small molecule photocrosslinker having UV photocrosslinking properties, characterized in that, The structural formula is shown as formula I: ； Formula I.

2. The method for preparing a small molecule photocrosslinking agent with UV photocrosslinking properties according to claim 1, characterized in that, Comprising the following steps: The aldehyde group in tris (4-formylphenyl) amine is reduced to benzyl alcohol to form tris-benzyl alcohol amine; The hydroxyl group in tris-benzyl alcohol amine is converted into an azide group under basic conditions through a nucleophilic aromatic substitution reaction to form a compound shown in formula I; wherein the azide reagent used is diphenyl phosphorazide, the molar ratio of diphenyl phosphorazide to tris-benzyl alcohol amine is 2-10:1, the basic substance used is 1,8-diazobicyclo[5.4.0]undec-7-ene, the reaction solvent is anhydrous tetrahydrofuran, the reaction temperature is 40℃, and the reaction time is 48 hours.

3. The method for preparing a small molecule photocrosslinking agent with UV photocrosslinking properties according to claim 2, characterized in that, The aldehyde group in tris (4-formylphenyl) amine is reduced to benzyl alcohol using sodium borohydride as the reducing agent, and the reaction solvent is a mixed solution of anhydrous ethanol and anhydrous tetrahydrofuran, and the reaction temperature is 40℃.

4. The application of the small-molecule photo-crosslinking agent with UV photo-crosslinking characteristics in the crosslinking of a polymer thin film according to claim 1.

5. Use according to claim 4, characterized in that, The polymer includes conjugated polymers and non-conjugated polymers.

6. The application of the small-molecule photo-crosslinking agent with UV photo-crosslinking characteristics in the photo-lithographic patterning of solution-processed semiconductor thin films according to claim 1.

7. Use according to claim 6, characterized in that, The solution-processed semiconductor includes organic semiconductors, quantum dots, and perovskites.

8. The application of the small-molecule photo-crosslinking agent with UV photo-crosslinking characteristics in the preparation of organic semiconductor devices according to claim 1.

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