CN104882540B - Molecular plane parallel to Si/SiO2Preparation method of porphyrin monomolecular layer on surface - Google Patents

Abstract

Charge transport in organic thin-film transistors (OTFTs) occurs in several molecular layers near the insulating/semiconductor layer interface, so the properties of this interface layer play a decisive role in the performance of the device. The present invention utilizes the methods of self-assembly and surface chemical growth to prepare a porphyrin monolayer on a Si/SiO ₂ substrate, so that the macrocyclic plane is parallel to the substrate surface; by using different metal ions (Zn ²⁺ , Fe ²⁺ , Cu ²⁺ , Ni ²⁺ , Co ²⁺ ) form a porphyrin monolayer with rich electronic structure to adjust the surface potential and charge distribution of Si/SiO ₂ ; provide an effective method for preparing organic molecule face‑on arrangement , and then study the effect of face‑on arrangement on device performance.

Description

Preparation method of porphyrin monolayer with molecular plane parallel to Si/SiO2 surface

technical field

Charge transport in organic thin-film transistors (OTFTs) occurs in several molecular layers near the insulating/semiconducting layer interface, so the properties of this interface play a decisive role in the performance of the device. The present invention uses the chemical self-assembly process to modify the surface of the Si/SiO ₂ substrate to change the properties of the Si/SiO ₂ substrate surface, thereby effectively controlling the orderly arrangement of organic molecules in a face-on manner, and studying the molecular face-on orderly arrangement. impact on device performance.

Background technique

Compared with traditional silicon-based thin-film transistors (Si-TFTs), which have problems such as high cost and environmental pollution, organic thin-film transistors (OTFTs) have the advantages of low cost, easy processing, and large-area manufacturing, and can be applied to liquid crystal displays and organic light-emitting displays. , organic photovoltaics, radio frequency identification technology and sensors, etc., have been deeply researched by academia and industry.

In an OTFT device, several organic material molecular layers on the interface of the inorganic substrate are conductive channels, and the arrangement of organic molecules directly determines the carrier transport capability, carrier density, and electrode surface work function (M.P.Nikiforov, U .Zerweck, P.Milde, C.Loppacher, T.H.Park, H.T.Uyeda, M.J.Therien, L.Eng, andD.Bonnell, Nano Lett. 2008, 8, 110.), which determines the performance of the device, so the preparation has Orderly arrangement, defect-free, and large-grain organic materials are very important. There are two arrangements of organic molecules: face-on (that is, the molecular plane is parallel to the substrate plane) and edge-on (that is, the molecular plane and the substrate plane have an inclination angle). The effects of face-on and edge-on arrangements on device performance Impact is very important.

Usually, the films formed by organic materials directly on the surface of Si/SiO ₂ are arranged in an edge-on manner. Researchers try to obtain face-on arrangement through interface modification. The self-assembled film of halogen-terminated aromatic and alkyl organosilanes promotes more pentacene molecules to adopt a face-on arrangement, but the pentacene is arranged in a polycrystalline form (KPPernstich, S.Haas, D.Oberhoff, C. Goldmann, DJ Gundlach, B. Batlogg, ANRashid, and G. Schitter, J. Appl. Phys. 2004, 96, 6431.). Introduction of long alkyl chains (nC ₁₈ H ₃₇ ), carboxyl, and pyridine groups (J.Otsuki, E.Nagamine, T.Kondo, K.Iwasaki, M.Asakawa, and K. Miyake, J.Am.Chem. Soc.2005, 127, 10400.), enabling porphyrin monolayers to be arranged in a face-on manner. Similarly, the monolayer film molecules formed on the atomically smooth graphite electrode (0001) are arranged in a face-on (that is, the molecular plane is parallel to the substrate plane); however, the organic materials that continue to be deposited on the monolayer film change the The arrangement is mainly in the edge-on arrangement (F. Bussolotti, SWHan, Y.Honda, and R.Friedlein, Phys.Rew.B 2009, 79, 245410.), obviously the strong π-π between molecules of organic materials Interactions change the way they are arranged.

So far, the preparation of OTFTs with large particles and organic material molecules arranged in a face-on manner has not been reported. Inorganic substrates have different crystal structures from organic materials, and the lattice constants or lattice symmetry are inconsistent. To control the orderly arrangement of organic materials, it is first necessary to reduce the influence of different lattice structures of inorganic substrates. This project uses methods such as self-assembly and chemical growth, and uses strong chemical bonds to fix the porphyrin monolayer with the molecular plane parallel to the substrate surface on the Si/SiO ₂ substrate; then use its highly conjugated planar structure to deposit on it The strong π-π interaction force of organic molecules controls the arrangement of organic molecules in a face-on manner.

Contents of the invention

A feature of the present invention is to provide a method for preparing a double-layer self-assembled film by chemical bonding, and prepare a stable porphyrin (formula 2) monomolecular layer on Si/ _SiO2 inorganic substance substrate, and its macrocyclic structure is parallel to substrate surface.

According to one aspect of the present invention, there is provided a method for forming a double-layer self-assembled film, the steps comprising:

1. Synthesis of two types of compounds, maleimide organosilane (formula 1) and porphyrin (formula 2)

Formula 1:

Formula 2:

2. Preparation of porphyrin monolayer with molecular plane parallel to Si/ _SiO2 surface

(a) cleaning and activating the Si/ _SiO2 substrate to form hydroxyl groups on its surface;

(b) Formation of self-assembled films of maleimide organosilane on Si/ _SiO2 substrates;

(c) A porphyrin monolayer is attached to the self-assembled film of maleimide organosilane by surface chemical growth, so that the porphyrin macrocycle structure is parallel to the substrate surface, and the monomolecular layer is stable.

Description of drawings

The above and other features and advantages of the present invention will be more clearly understood in conjunction with the following drawings and detailed description, wherein:

Figure 1 Schematic diagram of the self-assembly process;

Fig. 2 schematic diagram of water contact angle test of blank silicon wafer;

Fig. 3 maleimide organosilane (formula 1) self-assembled monolayer film water contact angle test schematic diagram;

Fig. 4 schematic diagram of water contact angle test of porphyrin (formula 2) self-assembled monolayer film;

Fig.5 XPS schematic diagram of N 1s;

Figure 6 XPS schematic diagram of S 2P;

Figure 7 maleimide organosilane proton nuclear magnetic resonance spectrum;

Figure 8 maleimide organosilane carbon nuclear magnetic resonance spectrum;

Figure 9 4-(3-bromopropoxy) benzaldehyde H NMR spectrum;

Fig. 10 4-(3-(thioacetyl) propoxy) benzaldehyde H NMR spectrum;

Fig. 11 5,10,15,20-tetra(4-(3-thioacetylpropoxy)phenyl)porphyrin H NMR spectrum;

Figure 12 5,10,15,20-Tetrakis(4-(3-thioacetylpropoxy)phenyl)porphyrin carbon nuclear magnetic resonance spectrum;

Fig. 13 5,10,15,20-tetrakis(4-(3-thioacetylpropoxy)phenyl)cobalt porphyrin H NMR spectrum;

Fig. 14 5,10,15,20-tetra(4-(3-thioacetylpropoxy)phenyl)nickel porphyrin H NMR spectrum;

Figure 15 5,10,15,20-Tetrakis (4-(3-thioacetylpropoxy)phenyl) copper porphyrin H NMR spectrum;

Fig. 16 5,10,15,20-tetra(4-(3-thioacetylpropoxy)phenyl)zinc porphyrin H NMR spectrum;

Figure 17 5,10,15,20-Tetrakis(4-(3-thioacetylpropoxy)phenyl)iron porphyrin H NMR spectrum;

Figure 18 5,10,15,20-Tetrakis(4-(3-mercaptopropoxy)phenyl)nickel porphyrin H NMR spectra.

Detailed Description of the Preferred Embodiment

Preferred embodiments of the present invention are described in detail below, so that the advantages and features of the present invention can be more easily understood by those skilled in the art.

Example 1:

(1) Synthesis of self-assembly material maleimide organosilane.

Add 200 ml of dry dichloromethane and 1.73 g (17.6 mmol) of maleic anhydride into a 500 ml flask, and stir under nitrogen protection. 3.90g (17.6mmol) of 3-aminopropyltriethoxysilane was dissolved in 20ml of dry dichloromethane, added to the flask, and stirred at room temperature for 1h. The solvent was removed by rotary evaporation to obtain a white powdery intermediate product, which was dried and weighed.

Add 200 ml of dry toluene and the white intermediate product obtained above into a 250 ml flask, and protect with N ₂ . Take 2.40g (17.6mmol) ZnCl ₂ , add it into the reaction system immediately, and raise the temperature to 80°C. Finally, 2.84 g (17.6 mmol) of hexamethyldisiloxane was dissolved in 20 ml of toluene, and added dropwise to the reaction system, and reacted for 5 h. After cooling to room temperature, ZnCl ₂ was removed by filtration, and the solvent was removed by rotary evaporation to obtain a colorless oily liquid with a yield of 50%. ¹ H NMR (400MHz; CDCl ₃ ): δ6.66(2H, s), 3.77(6H, m), 3.48(2H, t), 1.65(2H, m), 1.19(9H, t), 0.56(2H , t). ¹³ C NMR (400MHz): δ170.94, 134.12, 58.54, 40.51, 22.22, 18.35, 7.85.

(2) Synthesis of self-assembled material porphyrin (Formula 2).

The preparation of 4-(3-bromopropoxy)benzaldehyde:

Add 2.46g (12.2mmol) of 1,3-dibromopropane, 0.5g (4.1mmol) of p-hydroxybenzaldehyde, and 0.428g (6.1mmol) of K ₂ CO ₃ into a flask containing 30ml of acetone, under N ₂ protection. Stir at 80°C for 1 h, stop heating after the reaction, and cool the system to 0°C. Remove the solvent by rotary evaporation, add a small amount of distilled water, extract three times with chloroform, combine the organic phases, add an appropriate amount of anhydrous _MgSO4 for drying, after standing for half an hour, remove _MgSO4 by filtration, remove chloroform by rotary evaporation, and separate and purify by chromatography column (acetic acid ethyl ester:petroleum ether=1:4) to obtain a colorless oily liquid with a yield of 51%. ¹ H NMR (400MHz; CDCl ₃ ): δ9.89(1H, s), 7.83(2H, d), 7.00(2H, d), 4.20(2H, t), 3.61(2H, t), 2.36(2H , m).

Preparation of 4-(3-(thioacetyl)propoxy)benzaldehyde:

0.729g (3mmol) of 4-(3-bromopropoxy)benzaldehyde was added into a flask filled with 30ml of DMF, protected by _N2 and cooled to 0°C. 0.342g (3mmol) KSAc was dissolved in 5ml DMF, added dropwise to the reaction system within 30min, and stirred at room temperature for 3h. After the reaction, DMF was removed by rotary evaporation, a small amount of water was added, extracted three times with chloroform, the remaining residue in the reaction bottle was dissolved by adding a small amount of water and extracted three times with chloroform, the organic phases were combined, an appropriate amount of anhydrous MgSO ₄ was added, and static Set aside for half an hour. MgSO ₄ was removed by filtration, chloroform was removed by rotary evaporation, and column separation and purification (ethyl acetate:petroleum ether=1:4) yielded a white solid with a yield of 93%. ¹ H NMR (400MHz; CDCl ₃ ): δ9.91(1H, s), 7.84(2H, d), 7.00(2H, d), 4.12(2H, t), 3.09(2H, t), 2.37(3H , s), 2.13(2H, m).

Preparation of 5,10,15,20-tetrakis(4-(3-thioacetylpropoxy)phenyl)porphyrin:

Dissolve 0.067g (1mmol) of freshly distilled pyrrole and 0.238g (1mmol) of 4-(3-(thioacetyl)propoxy)benzaldehyde in a flask filled with 30ml of CH ₂ Cl ₂ and protect with N ₂ . Dissolve 0.114g (1mmol) trifluoroacetic _acid in 2ml _CH2Cl2 , slowly add to the reaction system, stir in the dark for 1.5h, then add 0.170g (0.75mmol) tetrachlorobenzoquinone (TCQ), reflux for 1h, the reaction is over . Heating was stopped, the system was cooled to room temperature, an appropriate amount of triethylamine was added, it was allowed to stand for half an hour and then filtered, the solvent was removed by rotary evaporation, and the chromatographic column was separated and purified to obtain a purple solid with a yield of 30%. ¹ H NMR (400MHz; CDCl ₃ ): δ8.87(8H, s), 8.13(8H, d), 7.26(8H, d), 4.30(8H, t), 3.24(8H, t), 2.43(12H , s), 2.27 (8H, m). ¹³ C NMR (400MHz): δ195.86, 158.60, 135.61, 134.77, 119.72, 112.72, 77.33, 77.01, 76.70, 66.49, 30.74, 29.53, 26.08.

Preparation of 5,10,15,20-tetrakis(4-(3-thioacetylpropoxy)phenyl)cobalt porphyrin:

Dissolve 30 mg (0.026 mmol) of porphyrin in 30 ml of chloroform, protect with N ₂ , heat to reflux, add 129.52 mg (0.52 mmol) Co(OAc) ₂ ·4H ₂ O to the reflux system, heat to reflux for 5 h, and the reaction ends. The system was cooled to room temperature, chloroform was removed by rotary evaporation, dissolved by adding CH ₂ Cl ₂ , washed with 10% NaHCO ₃ solution, washed twice with distilled water, dried with anhydrous MgSO ₄ , filtered, and the solvent was removed by rotary evaporation, and chromatographed Column separation gave a red solid with a yield of 88%. ¹ H NMR (400MHz; CDCl ₃ ): δ9.44(8H,br), 5.55(8H,br), 4.03(8H,br), 3.13(8H,br), 2.78(12H,br).

Preparation of 5,10,15,20-tetrakis(4-(3-thioacetylpropoxy)phenyl)nickel porphyrin:

Dissolve 30 mg (0.026 mmol) of porphyrin in 30 ml of DMF, protect with N ₂ , heat to reflux, add 64.0 mg (0.26 mmol) Ni(OAc) ₂ ·4H ₂ O to the reflux system, heat to reflux for 5 h, and the reaction ends. The system was cooled to room temperature, DMF was removed by rotary evaporation, dissolved by adding _CH2Cl2 , washed with ₁₀ % _NaHCO3 solution, washed twice with distilled water, dried with anhydrous _MgSO4 , filtered, solvent was removed by rotary evaporation, and chromatographed Column separation gave a red solid with a yield of 89%. ¹ H NMR (400 MHz; CDCl ₃ ): δ8.78 (8H, s), 7.91 (8H, d), 7.19 (8H, d), 4.24 (8H, t), 3.20 (8H, t), 2.41 ( 12H, s), 2.22(8H, m).

Preparation of 5,10,15,20-tetrakis(4-(3-thioacetylpropoxy)phenyl)copper porphyrin:

Dissolve 30 mg (0.026 mmol) of porphyrin in 30 ml of chloroform, protect with N ₂ , heat to reflux, add 52 mg (0.26 mmol) Cu(OAc) ₂ ·H ₂ O to the reflux system, heat to reflux for 5 h, and the reaction ends. The system was cooled to room temperature, chloroform was removed by rotary evaporation, dissolved by adding CH ₂ Cl ₂ , washed with 10% NaHCO ₃ solution, washed twice with distilled water, dried with anhydrous MgSO ₄ , filtered, and the solvent was removed by rotary evaporation, and chromatographed Column separation gave a red solid with a yield of 85%. ¹ H NMR (400MHz; CDCl ₃ ): δ7.07(8H,br), 4.20(8H,br), 3.17(8H,br), 2.38(12H,br), 2.19(8H,br).

Preparation of 5,10,15,20-tetrakis(4-(3-thioacetylpropoxy)phenyl)zinc porphyrin:

Dissolve 30 mg (0.026 mmol) of porphyrin in 30 ml of chloroform, protect with N ₂ , heat to reflux, add 113.9 mg (0.52 mmol) of Zn(OAc) ₂ ·2H ₂ O to the reflux system, heat to reflux for 5 h, and the reaction ends. The system was cooled to room temperature, chloroform was removed by rotary evaporation, dissolved by adding CH ₂ Cl ₂ , washed with 10% NaHCO ₃ solution, washed twice with distilled water, dried with anhydrous MgSO ₄ , filtered, and the solvent was removed by rotary evaporation, and chromatographed Column separation gave a purple solid with a yield of 98%. ¹ H NMR (400MHz; CDCl ₃ ): δ8.97(8H, s), 8.12(8H, d), 7.25(8H, d), 4.30(8H, t), 3.20(8H, t), 2.37(12H , s), 2.24(8H, m).

Preparation of 5,10,15,20-tetrakis(4-(3-thioacetylpropoxy)phenyl)iron porphyrin:

Dissolve 30 mg (0.026 mmol) of porphyrin in 30 ml of chloroform, protect with N ₂ , heat to reflux, add 51.69 mg (0.26 mmol) FeCl ₂ ·4H ₂ O to the reflux system, heat to reflux for 5 h, and the reaction ends. The system was cooled to room temperature, chloroform was removed by rotary evaporation, dissolved by adding CH ₂ Cl ₂ , washed with 10% NaHCO ₃ solution, washed twice with distilled water, dried with anhydrous MgSO ₄ , filtered, and the solvent was removed by rotary evaporation, and chromatographed Column separation gave a black solid with a yield of 70%. ¹ H NMR (400MHz; CDCl ₃ ): δ8.97(8H, s), 8.12(8H, d), 7.25(8H, d), 4.30(8H, t), 3.20(8H, t), 2.37(12H , s), 2.24(8H, m).

Preparation of 5,10,15,20-tetrakis(4-(3-mercaptopropoxy)phenyl)nickel porphyrin:

Weigh 120mg of Ni-porphyrin and place it in a flask filled with 60ml of chloroform and 18ml of methanol under _N2 protection. Weigh 182 mg of 20% CH ₃ NaS aqueous solution in 0.5 ml of methanol, add it to the above solution, stir at room temperature for about 1.5 h, and monitor the reaction progress by TLC (ethyl acetate: CH ₂ Cl ₂ =1:50), the reaction Evaporate the solvent after completeness, add water and chloroform to extract three times, the organic phase is regulated PH= ₆ with dilute HCl, then extract the organic solution with chloroform, add anhydrous MgSO Dry, filter, rotary evaporation removes solvent, chromatographic column separation (acetic acid Ethyl ester:CH ₂ Cl ₂ =1:50) to obtain a red solid with a yield of 30%. ¹ H NMR (400MHz; CDCl ₃ ): δ8.78 (8H, s), 7.91 (8H, d), 7.19 (8H, d), 4.24 (8H, t), 3.20 (8H, t), 2.41 (12H , s), 2.22(8H, m).

(3) Preparation of self-assembled membrane

Step 1: Sonicate a silicon wafer with a size of 1×1cm in sequence with acetone, ethanol, and ultrapure water for 10 minutes and dry it with N ₂ ;

Step 2: irradiating the cleaned Si/ _SiO2 substrate with UV- _O3 for 30min to form hydroxyl groups on its surface;

Step 3: Dip the activated silicon wafer in 10ml of maleimide organosilane in toluene (dry) solution (10 ^-3 M), N ₂ protection, heat to 75°C, self-assemble for 36h, to Si/SiO ₂ substrate A self-assembled film of a layer of maleimideorganosilane self-assembled on it;

Step 4: Utilize the reaction between maleimide and thiol, immerse the silicon wafer in 2ml of porphyrin in THF solution (5×10 ^-4 M), protect with N ₂ , heat to 55°C, and self-assemble for 30h, so that four The thiol (-SH) compound porphyrin is connected to the surface of Si/SiO ₂ /maleimide organosilane, so that the plane of the porphyrin macrocycle is parallel to the electrode surface.

(4) Characterization of materials

(a) X-ray photoelectron spectroscopy (XPS)

Figure 5 is the XPS schematic diagram of N 1s. The peak with the binding energy of 397ev in the figure is the characteristic peak position of the N element contained in maleimide organosilane, which indicates that maleimide organosilane self-assembled successfully on the Si/SiO ₂ surface.

Figure 6 is the S 2p XPS spectrum of porphyrin monolayer on Si/SiO ₂ substrate. The self-assembled films of different mercaptoporphyrins were further characterized by comparing the chemical environment of S 2p in different self-assembled films to illustrate the binding state of thiols to the substrate. The binding energy of the S 2p element of SH in the unbonded state should be 163–164 eV, while that of SC in the bonded state should be 162 eV. The binding energy of the XPS characteristic peak of the S 2p element in Fig. 6 is about 162eV, which indicates the formation of SC bonds, that is, porphyrin is successfully attached to the surface of Si/SiO ₂ /maleimide organosilane. Another characteristic peak with a binding energy of 168eV in Figure 6 is the oxidation peak of S 2p, which indicates that the sulfhydryl group (-SH) in porphyrin is partially oxidized during the self-assembly process.

(b) Water contact angle

The change in wettability of _SiO2 surface caused by surface modification was systematically characterized by contact angle measurement. Fig. 2 is that the contact angle of SiO ₂ surface is 49.77 °, Fig. 3 is that the surface contact angle of maleimide organosilane self-assembled film is 67.97 °, Fig. 4 is 5,10,15,20-tetrakis (4-(3-mercaptopropoxy The surface contact angle of base) phenyl) nickel porphyrin self-assembled film is 88.90°, the maleimide organosilane self-assembled film top group maleimide contains a hydrophilic group-carbonyl group, while the bonded porphyrin monolayer does not The hydrophilic group, so the water contact angle increases, which also proves that the maleimideorganosilane self-assembled film and the porphyrin monomolecular film were successfully prepared.

Claims (4)

1. a kind of prepare for modifying organic thin film transistor substrate Si/SiO₂Surface and the porphyrin that is arranged in a manner of face-on point The method of sublayer, it is characterised in that in Si/SiO₂One layer of 3- dimaleoyl imino propyl-triethoxysilicane of surface self-organization point Son recycles four functional groups of Porphyrin Molecule end to occur with the double bond in 3- dimaleoyl imino propyl-triethoxysilicanes Chemical bonding forms one layer of Porphyrin Molecule, and macrocyclic structure is parallel to substrate surface, is arranged in a manner of face-on.

It a kind of is prepared for modifying organic thin film transistor substrate Si/SiO 2. according to claim 1₂Surface and with The method for the Porphyrin Molecule layer that face-on modes arrange, it is characterised in that the metal ion that complex compound is formed with porphyrin is Zn²⁺, Fe²⁺, Cu²⁺, Ni²⁺, Co²⁺In any one.

It a kind of is prepared for modifying organic thin film transistor substrate Si/SiO 3. according to claim 1₂Surface and with The method for the Porphyrin Molecule layer that face-on modes arrange, it is characterised in that the functional group of Porphyrin Molecule side chain terminal be amino (- NH₂), any one in sulfydryl (- SH).

It a kind of is prepared for modifying organic thin film transistor substrate Si/SiO 4. according to claim 1₂Surface and with The method for the Porphyrin Molecule layer that face-on modes arrange, it is characterised in that the number of Porphyrin Molecule side chain carbon is in 3-11 Any one.