Micromolecular photo-crosslinking agent, preparation method and application

Abstract

The invention discloses a micromolecular photo-crosslinking agent, a preparation method and application, and belongs to the field of organic semiconductors. The structural formula of the micromolecular photo-crosslinking agent is as shown in a formula I: # imgabs0 #. The preparation method comprises the following steps: reducing an aldehyde group in tri (4-formyl phenyl) amine into benzyl alcohol to generate triphenylcarbinol amine; through a nucleophilic aromatic substitution reaction, hydroxyl in triphenylcarbinol amine is converted into an azide group under an alkaline condition, and the compound shown in the formula I is generated. The micromolecular photo-crosslinking agent disclosed by the invention has a UV photo-crosslinking characteristic, can be used for processing ultraviolet lithography patterning of polymer semiconductors through solution processing, is simple to synthesize, safe and efficient, and has the potential of large-scale production.

Description

Technical Field

[0001] The invention belongs to the field of organic semiconductors, and in particular relates to a small molecule photocrosslinking agent with UV light crosslinking properties, a preparation method and an application thereof. Background Art

[0002] Organic semiconductor materials have important applications in devices such as 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 multifunctional integration of organic semiconductor devices is the key to completing the transition from laboratory to industrial application. Photolithography is the core link in the large-scale, high-precision manufacturing of integrated circuits and micro-nano semiconductor components, and is an important way to achieve miniaturization and integrated application of electronic devices. However, organic semiconductor materials themselves do not have photolithography properties and require the addition of small molecule photocrosslinkers, but commonly used photocrosslinking groups still have many limitations, such as residual by-products, poor material compatibility, and low photocrosslinking reaction activity. Therefore, there is an urgent need to develop more efficient photocrosslinking materials that are more compatible with organic semiconductor materials.

[0003] The azide group has the advantages of high photosensitivity, fast reaction speed, and no residual byproducts. It is expected to provide new solutions for high-precision direct photolithography patterning of micro-nano organic semiconductors and multifunctional high-density integration. However, the existing azide-type cross-linking small molecules are all based on pentafluorobenzoic acid as the basic building block, with a single structure, and the synthesis process requires the use of sodium azide (explosive), and the reaction conditions are strict and dangerous. Therefore, it is urgent to develop azide-type small molecule photocrosslinkers that are safer, more efficient, and more compatible with organic semiconductors. Summary of the invention

[0004] The purpose of the present invention is to provide a small molecule photocrosslinker with UV light crosslinking properties, a preparation method and application thereof, with triphenylamine as the molecular skeleton, and an azide substituent group introduced as a photocrosslinking site. It can be added into a semiconductor film as a small molecule photocrosslinker to realize direct photolithography patterning of solution-processed semiconductor films.

[0005] To achieve the above object, the present invention adopts the following technical solution: In the first aspect, the present invention provides a small molecule photocrosslinker with UV light crosslinking properties, the core structure of which is triphenylamine, and the benzene ring contains an azide substituent group, and the structural formula is shown in Formula I:

[0006] Formula I.

[0007] In a second aspect, the present invention provides a method for preparing the small molecule photocrosslinker represented by the above formula I, comprising the following steps: The aldehyde group in tris(4-formylphenyl)amine is reduced to benzyl alcohol to generate tribenzyl alcoholamine; Through a nucleophilic aromatic substitution reaction, the hydroxyl group in triphenylmethanolamine is converted into an azide group under alkaline conditions to generate a compound shown in formula I.

[0008] Furthermore, in the preparation method, the reducing agent used to reduce the aldehyde group in 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°C.

[0009] Furthermore, in the preparation method, in converting the hydroxyl group in triphenylmethanolamine into an azide group, the azidation reagent used is diphenylphosphoryl azide, and the molar ratio of diphenylphosphoryl azide to triphenylmethanolamine is 2-10:1.

[0010] Furthermore, in the preparation method, the hydroxyl group in triphenylmethanolamine is converted into an azide group, the alkaline substance used is 1,8-diazobispiro[5.4.0]undec-7-ene, the reaction solvent is anhydrous tetrahydrofuran, the reaction temperature is 40° C., and the reaction time is 48 hours.

[0011] The present invention also provides the use of the small molecule photocrosslinking agent shown in the above formula I in the crosslinking of polymer films.

[0012] Wherein, the polymer includes conjugated polymer and non-conjugated polymer.

[0013] The present invention also provides the use of the small molecule photocrosslinking agent shown in the above formula I in the photolithography patterning of solution-processed semiconductor films.

[0014] The solution-processed semiconductors include organic semiconductors, quantum dots, perovskites and other materials.

[0015] The present invention also provides the use of the small molecule photocrosslinking agent shown in the above formula I in the preparation of organic semiconductor devices.

[0016] Among them, the organic semiconductor devices include organic light emitting diodes, organic field effect transistors, organic solar cells, organic integrated circuits, organic thermoelectric devices, etc.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects: 1. The raw materials used in the synthesis of the present invention are convenient and easy to obtain, the preparation process is safer and more efficient, the conditions are mild, and it is easy to industrialize and mass-produce; 2. The small molecule photocrosslinker of the present invention has excellent solution processing characteristics and better compatibility with organic semiconductors processed in solution; 3. The small molecule photocrosslinker of the present invention has excellent UV light crosslinking properties, can realize direct photolithography patterning of semiconductor thin films, simplifies the photolithography process, and has no residual by-products. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the compound TPA-3X in Example 1 of the present invention 1 H-NMR spectrum; Figure 2 is the compound TPA-3X in Example 1 of the present invention 13 C-NMR spectrum; Figure 3 This is a high-resolution mass spectrum of the compound TPA-3X in Example 1 of the present invention; Figure 4 This is a thermogravimetric analysis curve of compound TPA-3X in Example 1 of the present invention; Figure 5 This is an example diagram of using the compound TPA-3X in Example 1 of the present invention as a photocrosslinking agent to achieve high-precision photolithography patterning of a polymer semiconductor film; Figure 6 Spectral properties of the polymer semiconductor film before and after photolithography in Example 2 of the present invention, (a) absorption spectrum, (b) emission spectrum; Figure 7 This is an example diagram of photolithographic patterning of quantum dot light-emitting thin films using the compound TPA-3X in Example 1 of the present invention as a photocrosslinking agent; Figure 8 This is a schematic diagram of the structure of the electroluminescent device prepared in Example 4 of the present invention; Fig. 9 The performance test curves of the electroluminescent device prepared in Example 4 of the present invention are: (a) a graph showing the change of current density and brightness with voltage; (b) a graph showing the change of current efficiency with current density; and (c) a graph showing the electroluminescent spectrum of the device. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with specific examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention.

[0020] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should be the common meanings understood by those skilled in the art to which the present invention belongs. The raw materials, reagents, etc., unless otherwise specified, can all be obtained from public commercial channels. Example

[0021] The synthetic route of the compound (TAP-3X) represented by formula I is as follows: The preparation method comprises: Step 1: The reactant tri(4-formylphenyl)amine (TPA-3O) (0.8 g, 2.4 mmol) was dissolved in 10 mL of anhydrous ethanol and 25 mL of anhydrous tetrahydrofuran, and stirred thoroughly in an ice bath to dissolve. Then, sodium borohydride (NaBH4) (0.55 g, 14.5 mmol) was slowly added, and the temperature was gradually raised to 40°C to allow it to react fully for 12 h. After the reaction was completed, deionized water (100 mL) was added to the reaction bottle and stirred vigorously for 1 h to remove excess sodium borohydride. Finally, the organic phase was extracted with dichloromethane and saturated brine, and the product triphenylmethanolamine (TPA-3OH) was obtained after concentration, column chromatography, drying and other steps.

[0022] Step 2: The above product TPA-3OH (0.6 g, 1.8 mmol) was dissolved in 30 mL of anhydrous tetrahydrofuran, and then 1,8-diazobispiro[5.4.0]undec-7-ene (DBU) (0.95 g, 6.3 mmol) and diphenylphosphoryl azide (DPPA) (1.7 g, 6.3 mmol) were added in sequence, and the mixture was reacted at 40 °C for 48 h under nitrogen protection. After the reaction, about 10 mL of saturated sodium bicarbonate solution was added dropwise to the reaction flask and stirred for 10 min. Finally, the mixture was extracted with dichloromethane and saturated brine, and the organic phase was dried over anhydrous sodium sulfate, and then the product TPA-3X (0.45 g, 75%) was obtained by vacuum distillation, column chromatography purification, and drying.

[0023] Structural confirmation data such as Figure 1 and Figure 2 Shown: 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.

[0024] High resolution mass spectrometry test Figure 3 As shown, the molecular weight of TPA-3X (C21H19N10) is 411.1795.

[0025] Figure 4 Thermogravimetric analysis data of TPA-3X shows that the azide group decomposes at around 215°C. Example

[0026] The photolithographic patterning of the polymer semiconductor film is realized by solution processing based on the compound TPA-3X in Example 1 of the present invention, and the specific steps include: First, the polymer semiconductor material (Livilux ® SPG-01T, Sigma-Aldrich NO. 900441) was prepared into a 4 mg / mL toluene solution and stirred thoroughly at 100°C. Before use, it was filtered with a polyvinylidene fluoride filter with a pore size of 0.45 μm. At the same time, TPA-3X was prepared into a 4 mg / mL toluene solution and stirred thoroughly at room temperature. Then, the polymer semiconductor solution and the TPA-3X crosslinker solution were mixed in a certain proportion to prepare a mixed solution with a mass fraction of TPA-3X of 2 wt%. After that, the mixed solution was spin-coated on a pre-cleaned glass / silicon wafer substrate (1500 rpm, 60 s) to form a uniform luminescent film for subsequent photolithography.

[0027] During the photolithography process, the film is first transferred to a glove box for annealing (100°C, 15 min). Afterwards, the film is exposed to light (40 mW / cm2) using a UV lamp (240 nm-400 nm) through a high-precision mask. 2 , 60 s), and anneal the film again (100 ° C, 15 min) to make the cross-linking reaction more complete. Finally, the treated film is placed in chloroform for full development (20 s), and the surface solvent is blown dry with a nitrogen gun to present the target pattern. The specific patterning example is Figure 5 As shown, combined Figure 6 The film spectral data shown demonstrate that the crosslinker does not destroy the optical properties of the polymer semiconductor film. Example

[0028] The photolithography patterning of the quantum dot film is realized based on the compound TPA-3X in Example 1 of the present invention, and the specific steps include: First, the quantum dot material was prepared into a 10 mg / mL chlorobenzene solution and stirred at 100°C for 24 hours. At the same time, TPA-3X was prepared into a 10 mg / mL chlorobenzene solution and stirred 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 mass fraction of TPA-3X of 5 wt%. After that, the mixed solution was spin-coated on a pre-cleaned glass / silicon wafer substrate (1500 rpm, 60 s) to form a uniform luminescent film for subsequent photolithography.

[0029] During the photolithography process, the film is first transferred to a glove box for annealing (100°C, 15 min). Afterwards, the film is exposed to light (30 mW / cm2) using a UV lamp (240 nm-400 nm) through a high-precision mask. 2, 20 s), and anneal the film again (100 ° C, 15 min) to make the cross-linking reaction more complete. Finally, the treated film is placed in chloroform for full development (20 s), and the surface solvent is blown dry with a nitrogen gun to present the target pattern. The specific patterning example is Figure 7 shown. Example

[0030] The application of the polymer semiconductor film prepared by the compound TPA-3X according to Example 1 of the present invention in an electroluminescent device comprises the following specific steps: (1) The indium tin oxide (ITO) conductive glass was cleaned with detergent, ethanol, acetone, isopropanol and deionized water respectively, dried with a nitrogen gun and treated with a UV ozone cleaner for 10-15 min, with ITO as the anode.

[0031] (2) Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT:PSS) was spin-coated on an ITO substrate (3000 rpm, 60 s) and then annealed in air at 120 °C for 15 min to obtain a hole injection layer with a thickness of approximately 40 nm.

[0032] (3) The solution containing 2 wt% TPA-3X prepared in Example 2 was spin-coated on the PEDOT:PSS layer (1500 rpm, 60 s) to obtain a uniform film with a thickness of 50-70 nm. The film was then transferred to a glove box and annealed at 100 °C for 15 min. Afterwards, the film was exposed to ultraviolet light (240 nm-400 nm) through a high-precision mask (40 mW / cm 2 , 60 s) to initiate the cross-linking reaction.

[0033] (4) Finally, the film was transferred to a thermal evaporation chamber and -5 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), lithium fluoride (LiF) and aluminum (Al) electrodes were deposited in sequence under the vacuum of mbr to obtain an effective luminous area of ​​4 mm 2 The polymer electroluminescent device has a structure as shown in Figure 8 shown.

[0034] After testing, the performance curve of the prepared device is as follows Fig. 9 As shown in the figure, the maximum brightness of the polymer electroluminescent device prepared based on the original film is 13000 cd m -2 , the maximum current efficiency is 2.0 cd A -1The device prepared by adding the photocrosslinker TPA-3X (2 wt%) and exposing the crosslinked film has a maximum brightness of 5200 cd m -2 , the maximum current efficiency is 1.6 cd A -1 In addition, the peak values ​​of the electroluminescence spectra of the devices based on the two films are both at 500 nm. It can be seen that after adding the photocrosslinker and UV exposure, the luminescence brightness of the device will decrease, but the purity of the luminescence color will not be affected.

[0035] The present invention has been disclosed above with preferred embodiments, but they are not intended to limit the present invention. Any technical solutions obtained by adopting equivalent replacement or equivalent transformation solutions fall within the protection scope of the present invention.

Claims

1. A small molecule photocrosslinker with UV light crosslinking properties, characterized in that: Its structural formula is shown in Formula I: Formula I.

2. The method for preparing a small molecule photocrosslinking agent having UV light crosslinking properties according to claim 1, characterized in that: The steps include: The aldehyde group in tris(4-formylphenyl)amine is reduced to benzyl alcohol to generate tribenzyl alcoholamine; Through a nucleophilic aromatic substitution reaction, the hydroxyl group in triphenylmethanolamine is converted into an azide group under alkaline conditions to generate a compound shown in formula I.

3. The method for preparing a small molecule photocrosslinking agent having UV light crosslinking properties according to claim 2, characterized in that: The reducing agent used to reduce the aldehyde group in 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°C.

4. The method for preparing a small molecule photocrosslinking agent having UV light crosslinking properties according to claim 2, characterized in that: In converting the hydroxyl group in triphenylmethanolamine into an azide group, the azidation reagent used is diphenylphosphoryl azide, and the molar ratio of diphenylphosphoryl azide to triphenylmethanolamine is 2-10:

1.

5. The method for preparing a small molecule photocrosslinking agent having UV light crosslinking properties according to claim 2, characterized in that: The hydroxyl group in triphenylmethanolamine is converted into an azide group. The alkaline substance used is 1,8-diazobispiro[5.4.0]undec-7-ene. The reaction solvent is anhydrous tetrahydrofuran. The reaction temperature is 40° C. and the reaction time is 48 hours.

6. Use of the small molecule photocrosslinking agent with UV light crosslinking property according to claim 1 in crosslinking of polymer films.

7. The use according to claim 6, characterized in that: The polymer includes conjugated polymers and non-conjugated polymers.

8. Use of the small molecule photocrosslinking agent with UV light crosslinking properties according to claim 1 in photolithography patterning of solution-processed semiconductor films.

9. The use according to claim 8, characterized in that: The solution-processed semiconductors include organic semiconductors, quantum dots and perovskites.

10. Use of the small molecule photocrosslinking agent with UV light crosslinking property according to claim 1 in the preparation of organic semiconductor devices.

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