RU2610606C2 - Process for obtaining of composite material based on polymer matrices for microelectronics - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a composite material for microelectronics. The method comprises preparing a liquid polymer base by dissolving polymer in organic solvent, introducing of metal phtalocyanine into the obtained solution , mixing until formation of a homogeneous liquid mixture, introducing the micro- and nano-sized particles of an inorganic substance from semiconducting, metallic and magnetic materials into it, mixing until homogeneous mass is obtained and drying at 26-40°C to remove the solvent. Polystyrene, polyvinylidene fluoride, polymethyl methacrylate, polyvinyl chloride, poly-3-4-ethylenedioxythiophene with polystyrene sulphonic acid, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate are used as polymer. Organic solvent is selected from tetrahydrofuran, toluene, benzene, ethyl alcohol.

EFFECT: invention provides a composite material of a functional purpose having photovoltaic, luminescent, semiconducting and resistive properties.

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Description

The invention relates to methods for producing a new generation of semiconductor materials that can be used in organo-and optoelectronics, solar energy, the manufacture of sensor devices. The main advantage of the material obtained is the combination of the properties of the metal-dielectric-semiconductor system at the molecular level. The invention can be particularly effectively applied in the production of solar cells, LEDs and thin-film microcircuits using the inkjet printing method as a method of applying composite material to a substrate (work surface). This method allows you to apply the manufactured composite to a plastic substrate in the form of quickly drying paint. The thickness, width and geometry of the finished bus is determined by the printer settings and print mode.

The technical problem solved by the invention is the environmental friendliness and safety of the manufacture of polymer composite materials for functional purposes in modern microelectronics.

To create elements of organoelectronics, organometallic molecular epitaxy, vacuum and thermal spraying are used. These methods make it possible to obtain ultrathin layers of sandwich structures based on organic semiconductors and synthetic dyes. But as disadvantages, it should be noted the low rate of synthesis of materials, the high cost of production, a small amount of synthesized substance, ensuring thermal stability of the starting components.

The method of inkjet printing and watering the substrate also has a technological drawback - the printing system has certain requirements for the viscosity of liquid-phase components, otherwise the application speed control will not be performed, and the layer will turn out to be inhomogeneous, defective.

Another direction in the technique of applying composite polymeric materials is the method of liquid droplet adsorption, the advantage of which is simplicity and economy.

Known methods for the manufacture of organic semiconductor systems from phthalocyanines and porphyrins, allowing using ultrahigh vacuum, atomically clean surface and directed gradients of concentration and temperature to obtain similar in topology, but inferior in properties to the proposed material (1. L.-K. Chau, S.- Y. Chen, NR Armstrong, G.Ε. Collins, C. D. England, VS Williams, ML Anderson, TJ Schuerlein, PA Lee, KW Nebesny, BA Parkinson & C. Arbor, Organic / Inorganic Molecular Beam Epitaxy (O / I-MBE): Formation and Characterization of Ordered Phthalocyanine Thin Films - Photoelectrochemical Processes ”, Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 252, 1, 67-77, 1994.

2. S.R. Forrest, Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques, Chem. Rev. 97, 1793-1896, 1997.

3. H. Masahiko, S. Hiroyuki, Y. Akira, G.F. Anthony, “Epitaxial growth of organic thin films by organic molecular beam epitaxy”, Japanese Journal of Applied Physics, Part 2, 28, p. L 306-L 308, 1989).

A known method for producing composite materials based on a matrix of [2-methoxy-5- (2'-ethylhexyloxy) -1,4-phenylene-vinylene] (MEN-PPV), into which organic materials (fullerenes, nanotubes, which are in demand) are added from solution ) The introduced additives act as electron donors and acceptors, making it possible to obtain photovoltaic cells or photodiodes from the original polymer (X. Deng, L. Zheng, C. Yang, Y. Li, G. Yu, and Y. Cao, “Polymer Photovoltaic Devices Fabricated with Blend MEHPPV and Organic Small Molecules ", J. Phys. Chem. B, 108, 11, pp 3451-3456, 2004).

A known method of producing composite materials based on a matrix of MEH-PPV, the properties of which are changed at the stage of synthesis. For the introduction of nanosupplements and third-party molecular groups, the complex method of reversible incremental segmentation polymerization of the molecular chain (RAFT polymerization) of 4-chloromethylsterol is used after combining with a specific type (changing the luminescent or transport properties of MEH-PPV) oligomer (AJ Tilley, M. Chen, SM Danczak, KP Ghiggino and JM White, “Electronic energy transfer in pendant MEH-PPV polymers”, Polym. Chem., 3, 892-899, 2012).

A known method of producing composite materials based on a matrix of MEH-PPV, in which polystyrene molecules are introduced. The finished composite is a thin polymer layer (A. Marletta, V. Goncalves, and Debora T. Balogh, Photoluminescence of MEH-PPV / PS Blends, Brazilian Journal of Physics, 34, 2B, p. 697-698, 2004) .

A known method of producing composite materials for organic heterojunctions based on a matrix of MEH-PPV, in which derivatives of fullerenes- [6,6] -phenyl-C61-methyl butyric acid ester (PCBM) are dissolved. In addition to this composite, a complex system of polymer-inorganic materials based on poly (3,4-ethylenedioxythiophene) -poly (styrene sulfonate) and indium oxide (B. Minnaert and M. Burgelman, Modeling MEH is used to improve contact properties and accelerate charge carriers -PPV: PCBM (1: 4) bulk heterojunction solar cells ”, Proceedings of NUMOS, B. Minnaert et al. Gent, 28-30 March 2007 Numos 2007, pp. 327-339).

A known method for producing composite materials based on a matrix from MEH-PPV in which organophilic montmorillonites (OMMT) are dissolved, and based on this mixture, peeled films of MEH-PPV / OMMT composites are made (C.J. Jing, LS Chen, Yi Shi, Xi G. Jin, "Synthesis of Exfoliated MEH-PPV / Clay Nanocomposites", Chinese Chemical Letters, 16, 8, pp. 1117-1120, 2005).

A known method for producing composite materials based on a matrix of [2-methoxy-5- (2'-ethylhexyloxy) -1,4-phenylene-vinylene], into which (2,4,7-trinitrofuorin) -TNF is introduced as electron acceptors . It was shown that the acceptor impurity can both penetrate into the polymer coil and surround it, forming in both cases with MEH-PPV molecules a charge-transfer complex (Parashchuk O.D., Sosorev A.Yu., Bruevich V.V., Parashchuk D.Yu. Threshold formation of an intermolecular complex with charge transfer of a semiconductor polymer, Letters in JETP, 91, 379-384, 2010).

The main synthesis methods in the above information sources are molecular beam epitaxy, directed synthesis of high molecular weight compounds and polymer chemistry.

However, the known methods do not guarantee the presence of the finished composite material transport and luminescent properties simultaneously in combination with an arbitrary shape and geometry of the sample. In particular, some of the examples cited describe the preparation of a material that requires a complex sandwich system from a MIS structure for optimal operation, which does not have ductility and requires energy-intensive manufacturing costs.

The second disadvantage of the described methods is the use of complex reagents and chemical reactions during the dissolution or change of the polymer coil of the original matrix. Thirdly, the described synthesis methods do not provide such mechanical properties of materials as flexibility and ductility. The fourth drawback of these methods is the fact that these methods do not allow you to adapt new composite materials to a wide class of technological problems. Standard TIR structures are initially manufactured for a specific technological scheme of production, and their reorientation to other industries in most cases is impossible. The fifth drawback is the use of a large number of high-tech objects (fullerenes, graphene, nanotubes) as an effective additive in the polymer. The use of such components imposes stringent conditions on the performance and purity of materials. The latter, in turn, significantly complicates the transition from laboratory research to mass production of quality products.

Polymer composite materials are widely used in modern industry.

A known method of producing a composite ferromagnetic semiconductor material by the method of mechanochemical synthesis from mixtures of polymers and nanoscale particles of iron. As the initial reagents, we used polyaniline (emeraldine base) with M _w = 5 × 10 ³ for the undoped form, polystyrene with M _w = 2,3 × 10 ⁵ and M _n = 1,4 × 10 ⁵ , iron trichloride FeCl ₃ × 6H ₂ O and elemental sulfur. These components were selected taking into account the possibility of obtaining polymer composites based on them, which could simultaneously have semiconductor and ferromagnetic properties, as well as have a certain thermoplasticity, which makes it possible to produce thin films from them. For mechanochemical reactions, mixtures of powders of polyaniline, PS, iron salts and elemental sulfur were prepared. Polyaniline and PS were used in a 1: 1 ratio. Mixtures of iron and sulfur salts [FeCl ₃ ⋅ 6H ₂ O + S] were prepared at various molar ratios α (FeCl ₃ ⋅ 6H ₂ O) :( 1-α) S. It was found that at α = 0.3 the most efficient formation of magnetic particles of iron is observed. The prepared mixtures were further processed for 20 min at room temperature in a Fritsch Vibratory Micro Mill Pulverisette ball mill. Finished samples for measuring conductivity were thin films of composites 0.2 mm thick (Aleksandrov I.A., Karmilov A.Yu., Shevchenko V.G., Obolonkova E.S., Aleksandrov A.I., Solodovnikov S.P. Ferromagnetic semiconductor material obtained by the method of mechanochemical synthesis from mixtures of polymers and nanosized iron particles, High Molecular Compounds, Series B, 2009, Volume 51, No. 8, pp. 1573-1577).

A common disadvantage of the above methods, as well as the prototype, is the strict specificity of the materials used, i.e. in order to introduce a new metal or molecular impurity of the required chemical composition and size into the polymer matrix, several cycles of chemical reactions must be rearranged. It should also be noted that the known methods do not allow to obtain samples with a multidispersed set of nanosized particles.

The technical result of the invention is a polymer composite material of functional purpose, having photovoltaic, luminescent, semiconductor and resistive properties.

The technical result is achieved by a method of obtaining a composite material based on a polymer matrix, including the preparation of a liquid polymer base by dissolving a polymer selected from the group consisting of polystyrene, polyvinylidene fluoride, polymethyl methacrylate, polyvinyl chloride, poly-3-4-ethylenedioxythiophene with polystyrene sulfonic acid, poly (3,4- ethylenedioxythiophene) polystyrene sulfonate, in an organic solvent selected from the group consisting of tetrahydrofuran, toluene, benzene, ethyl alcohol, followed by introduction into metalloftalotcianinov first solution by stirring to form a homogeneous liquid mixture, introducing it in the micro- and nano-sized particles of inorganic compounds from the group of semiconductor, metal, and magnetic substances, stirring until a homogeneous mass, and drying at a temperature of 26-40 ° C to remove solvent. [2-Methoxy-5- (2'-ethylhexyloxy) -1,4-phenylene-vinylene] -polystyrene is preferably used as the polymer.

As the polymer matrix, glucose can be used. As metallophthalocyanine use phthalocyanine lanthanide or phthalocyanine aluminum chloride; powders of silicon or titanium dioxide in the form of rutile or nano- and microparticles of metal powders of zinc or copper are used as an inorganic substance.

The essence of the proposed method lies in the selection of such a polymer system in which the dissolution of heterocyclic complexes such as phthalocyanine metal or semiconductor powders is possible. The main components in this composite material are molecules of heterocyclic complexes - phthalocyanines. Phthalocyanines are widely used in industry as lightfast dyes. This is due to the fact that, being in an uncharged state, the phthalocyanine molecule has a dark blue color. However, during oxidation or reduction (i.e., changing the sign of the charge in one direction or another), the color of the phthalocyanine can change to red or green. A large number of metal phthalocyanines (PCM) were synthesized and studied. In general, PCMs have a number of interesting special properties: 1) Phthalocyanines easily crystallize and sublimate; 2) These compounds have high thermal and chemical resistance. In air, they practically do not decompose up to temperatures of 400-500 ° C, and in vacuum most phthalocyanines do not decompose up to 900 ° C. They do not interact with strong acids (concentrated sulfuric acid) and strong bases. Only very strong oxidizing agents (dichromates or cerium salts) can destroy these molecules to phthalmide or phthalic acid; 3) Phthalocyanines have a strong optical absorption in the visible region; 4) All elements, starting from subgroup IA and ending with subgroup VB of the periodic system, can form compounds with phthalocyanine rings. The redox properties of a molecule depend on the nature of the metal atom in PCM. Phthalocyanines crystallize to form a monoclinic base-centered lattice. There are two Pc molecules per unit cell. Polymorphic modifications of PC-α, β are known.

Commercially available polymers such as polystyrene, polyvinylidene fluoride, polymethyl methacrylate, polyvinyl chloride, poly-3,4-ethylenedioxythiophene with polystyrene sulfonic acid, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate, or substances from the saccharide class can also be used as the basic component of the matrix.

As solvents in the inventive method, the following are used: tetrahydrofuran, toluene, benzene.

A wide range of additives introduced into the polymer matrix makes it possible to determine the physical properties of the finished composite material — dielectric, semiconductor, semimetal. In the resulting material, it is possible to change such characteristics as the quantum yield of photoluminescence, resistance, concentration of charge carriers by several orders of magnitude, and the absorption (transmission), magnetic, and dielectric permittivity can vary significantly.

The thickness of the obtained composite materials can vary from 10 nm to several millimeters without loss of sample quality.

The number of powder and polymer inclusions in the composite material at the production stage can vary from 2 to the limit number determined by the mechanical properties of the polymer matrix (so that the finished material does not become loose and does not crumble).

The finished composite material can be applied both to a substrate of any type (depending on the problem statement), and to specially prepared structures (such as interdigital, classical metal-dielectric-semiconductor structure) or microchips for electronic products, non-invasive technologies in medicine, sensorics.

Finished composite materials can be flexible, like elastic polymers, and hard and hard, like glassy oxides. Adding into the solution of the composite mixture the appropriate plasticizer matrix polymer allows you to get a flexible and elastic material with the specified parameters of the angle of inclination and bending.

The invention is illustrated using FIG. 1, 2 and 3, which show:

FIG. 1. Images of scanning electron microscopy for a composite material based on MEH-PPV-polystyrene molecules with the addition of PcAlCl and zinc metal granules: A - resolution 50 μm; In - resolution of 5 microns; C - 500 nm.

FIG. 2. Photoluminescence of composite materials.

Curve 1 - MEHPPV-Zn-PcAlCl composite

Curve 2 - Polystyrene-Zn-Alloy-PcAlCl composite

FIG. 3. Photograph of a composite material based on MEH-PPV-Zn-PcAlCl composite, luminescent under the influence of laser radiation.

FIG. 4. Volt-ampere characteristic of a three-component composite sample consisting of polystyrene, phthalocyanine aluminum chloride and metal dust.

FIG. 5. The dark current-voltage characteristic of phthalocyanine aluminum chloride in the MEH-PPV matrix. The number of the experimental curve corresponds to an increase in the concentration of heterocyclic complexes in the composite.

FIG. 6. Measurement of the activation energy of erbium phthalocyanine in a polystyrene matrix. The activation energy in the composite is E _(A) = 0.50 (eV), The activation energy in pure erbium phthalocyanine is E _{(A) (PURE PCER)} = 0.62 (eV).

FIG. 7. Measurement of the photoconductivity kinetics of three composites consisting of a polystyrene matrix and lutetium phthalocyanines deposited on a soft elastic surface. The number of the experimental sample corresponds to an increase in the concentration of heterocyclic complexes in the composite.

FIG. 8. Temperature dependence of conductivity for an organic heterosystem based on monophthalocyanine molecules with the addition of MEH-PPV, plotted in coordinates (σΤ, Τ ^-1 ). Curve 1 MEH-PPV with the addition of PcCu complexes and metal zinc granules; curve 2-MEH-PPV-polystyrene with the addition of PcAlCl and metal zinc granules.

Example 1. At step 1, 0.833 mg of polystyrene was taken and dissolved at room temperature in tetrahydrofuran (THF) with a mass ratio of polystyrene: THF = 1: 5. The dissolution time was 15 minutes. The polystyrene-THF mixture was mixed in an ultrasonic bath for 30 minutes with a vibration frequency of 40 kHz until an equilibrium distribution of polymer molecules in the solution volume was achieved. Phthalocyanine molecules (initially dried and granular) in the form of a free-flowing powder in the amount of 0.0278 mg were added to a homogeneous prepared mixture of THF and dissolved polystyrene. For more efficient penetration of phthalocyanine complexes between the polymer units, the phthalocyanine-polymer-THF mixture was infused for 20 minutes (to accelerate the process, you can immerse the container with the mixture in an ultrasonic bath for 1 ÷ 3 min). Ultrafine metal dust was added to the resulting mixture of three components (the reagent was taken from standard tested materials for the production of pyrotechnics). The concentration of the metal powder was 0.208 mg. The four-component mixture was thoroughly mixed to obtain a homogeneous mass (the process can also be carried out using an ultrasonic bath). Moreover, the mass ratio of the components of the polymer: heterocycle: additive reaction is 1: 30: 4.

In step 2, the mixture obtained in the first step was poured into the desired shape or a composite solution was applied to the desired substrate.

At stage 3, the finished sample is dried at room temperature for 30 hours.

In step 4, to remove water vapor and THF, the composite material was placed in a furnace and heated at a temperature of 55 ° С for 4 h.

Example 2. As a sample for the polymer matrix, a combination of compounds was taken: polyvinylidene fluoride, polymethyl methacrylate, polyvinyl chloride, poly-3,4-ethylenedioxythiophene with polystyrene sulfonic acid, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate. The mass ratio of polymer: heterocycle: additives is the same as in example 1, 1: 30: 4.

Example. 3. Glucose was taken as a matrix for the manufacture of the composite material, ethanol was used as an easily evaporated solvent, and brilliant greens and iodine could be used as highly effective additives. In this case, to ensure the transport properties of the composite, copper powder was introduced into the mixture. The mass ratio of components: polymer: heterocycle: additives - 1: 1-30: 4.

Example 4. To improve the mechanical properties of the composite material (for example, increasing the bending angle), plasticizers can be added to the matrix as an additional component. It should be noted that each polymer has its own plasticizer molecules. The concentration of plasticizer should be calculated based on the amount of synthesized composite mixture.

Example 5. Instead of metal powders, additives can be nanocrystals of semiconductor or dielectric materials, as well as specially synthesized quantum dots or ferromagnetic impurities. Meso- and macroporous silicon powders, silicon powders obtained by the plasma-chemical method, and titanium dioxide powder in the modification of rutile were taken for the production of test samples. The mass ratio of polymer: heterocycle: additives is the same as in example 1, 1: 30: 4.

Thus, it can be seen from the presented data that a simple and effective method for producing composite materials with a set of optical, semiconductor, and thermoelastic properties from multidispersed silicon powders, metal powders, heterocyclic compound molecules, and a typical set of polymers using rapidly evaporating solvents has been developed.

Claims (7)

1. A method of obtaining a composite material based on a polymer matrix, comprising preparing a liquid polymer base by dissolving a polymer selected from the group consisting of polystyrene, polyvinylidene fluoride, polymethyl methacrylate, polyvinyl chloride, poly-3-4-ethylenedioxythiophene with polystyrene sulfonic acid, poly (3,4-ethylenedioxythiophene ) polystyrene sulfonate, in an organic solvent selected from the group consisting of tetrahydrofuran, toluene, benzene, ethyl alcohol, followed by addition of metallophthalocyanine, ne mixing is until a homogeneous liquid mixture, introducing it in the micro- and nano-sized particles of inorganic compounds from the group of semiconductor, metal, and magnetic substances, stirring until a homogeneous mass, and drying at a temperature of 26-40 ° C to remove solvent. 2. The method according to p. 1, characterized in that the polymer used is [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene-vinylene] -polystyrene. 3. The method according to p. 1, characterized in that glucose is used as the polymer matrix. 4. The method according to p. 1, characterized in that the phthalocyanine of the lanthanide is used as metallophthalocyanine. 5. The method according to p. 1, characterized in that the metal phthalocyanine is aluminum phthalocyanine. 6. The method according to p. 1, characterized in that the inorganic substances used are powders of silicon or titanium dioxide in the form of rutile.             7. The method according to p. 1, characterized in that as inorganic substances use nano - and microparticles of metal powders of zinc or copper.

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