CN103897392B - A kind of thin-film solar cells fluorinated polyimide film and preparation method thereof - Google Patents

Abstract

A kind of flexibility or thin-film solar cells fluorinated polyimide film and preparation method thereof, the component of this film includes: fluorinated polyimide；Nanometer aluminium powder.Utilize that screw is blended, extrusion equipment is by fluorinated polyimide；Nanometer aluminium powders etc. are blended, and extrude and import casting head through filtering, and cooled, drawing-off, the operation such as batch and obtain fluorinated polyimide film used for solar batteries.Product out made by the present invention, invests thin-film solar cells light receiving surface or does the upper encapsulating film of solar cell, directly improves the flexible or generating efficiency of thin-film solar cells.

Description

Fluorinated polyimide film for thin-film solar cell and preparation method thereof

technical field

The invention relates to a fluorinated polyimide film for flexible or thin-film solar cells and a preparation method thereof. The efficiency of the flexible or thin-film solar cells is directly improved by using the film to encapsulate the light-incident surface of the flexible or thin-film solar cells.

Background technique

Due to the high-tech material aromatic polyimide (PI) resin is insoluble, refractory, the highest level of heat resistance, cold resistance, oxidation resistance, radiation resistance, chemical resistance, good mechanical and electrical properties and are widely used in many fields. In particular, optically transparent PI films have special applications in some fields, such as flexible solar radiation protection materials, solar cell substrate materials, flexible transparent conductive film substrate materials, alignment film materials for liquid crystal displays, optical waveguide materials and planar materials in the communication field. Optical half-wave plates for light wave circuits, etc.

Due to the rigidity of the main molecular chain and strong intermolecular interaction of commercial standard polyimides, they are often insoluble and infusible, and their processing performance is poor, which limits their further applications, especially difficult to be processed into films and coatings. In addition, standard polyimide polymer films have deep color (yellow or brown) and poor optical transparency due to the high aromatic conjugation and strong charge transfer complexation in the molecular chain; while Light-colored transparent polyimide has important application value in liquid crystal display and optical waveguide. Therefore, it is a very meaningful research work to design and modify the molecular structure of polyimide to prepare functional polyimides with good solubility, film-forming properties, and high optical transparency. In recent years, studies have found that fluorine-containing polyimides generally exhibit better solubility properties, especially polyetherimides containing trifluoromethyl-substituted structures. Such polyimides are usually obtained by polycondensation of fluorine-containing diether diamine monomers and common dianhydride monomers. Due to the large free volume of the trifluoromethyl group and the unique physical and chemical properties of the fluorine atom, such as greater electronegativity, smaller atomic radius, and lower molar polarizability, this type of polyimide also exhibits Compared with traditional polyimide, it has better optical properties, dielectric properties and lower moisture absorption. However, due to the introduction of a large proportion of flexible ether bonds (two in each structural unit) into the main chain of this type of fluorine-containing polyetherimide, the high temperature resistance of this type of polymer is often better than that of standard polyimide. Amines have a large decrease, and their glass transition temperatures are mostly between 200 and 300 °C. With the continuous deepening of research on soluble and functional polyimide materials, fluorenyl-containing Cardo-type polyimides have gradually received more and more attention. Due to the huge free volume and rigid fused ring structure of the fluorenyl group, this kind of polyimide has excellent comprehensive properties, such as excellent solubility in organic solvents, and some varieties are soluble in chlorinated hydrocarbons and amides solvents; excellent resistance Thermal and thermal oxidation stability; good mechanical properties and low dielectric constant, etc. In order to obtain new functional polyimide film materials with high solubility and high optical transparency, in the effective utilization of solar energy: photovoltaic utilization is the fastest growing and most dynamic research field in recent years. Generally, the production of solar cells is mainly based on semiconductor materials, which use photoelectric materials to absorb light energy and generate photoelectric conversion reactions to generate electricity. According to the different materials used, solar cells can be divided into: 1. Silicon solar cells; 2. Solar cells made of inorganic salts such as gallium arsenide III-V compounds, cadmium sulfide, copper indium selenide and other multi-component compounds; 3. Solar cells made of functional polymer materials; 4. Nanocrystalline solar cells, etc. The product with the highest working efficiency in the prior art is based on III-V semiconductor inorganic materials as raw materials. For example: gallium arsenide/germanium single-junction quantum well trap structure, its photoelectric conversion efficiency can reach >18%; and solar cells with multiple junction quantum well trap structure, such as: indium gallium phosphide/arsenide Gallium/germanium, whose photoelectric conversion efficiency can be as high as >30%. At present, silicon is the most widely used, including amorphous silicon, with a photoelectric conversion efficiency of about 9%; polycrystalline silicon, with a photoelectric conversion efficiency of about 14%; and monocrystalline silicon, with a photoelectric conversion efficiency of about 17%. Although in terms of price, the group VI element Si is cheaper than the III-V group semiconductor GaAs, but its manufacturing price is still much more expensive than polymer organic solar cells; and in application, it is light in weight and has no risk of rupture. The fully plasticized organic solar cells can be realized by printing. In addition to lower prices, they are more suitable for the needs of portable electronic products, and can be used normally indoors or on cloudy days (this is something that silicon solar cells cannot achieve. ), making its practicability and market application breadth more enhanced.

Solar cells are a key technology that will advance cleaner energy production. But the cost of solar cells has reduced the economic competitiveness of solar technology. To overcome this problem, thin-film solar cells are currently widely used technology, which can greatly reduce the use of expensive semiconductor materials, but thin-film solar cells have low light absorption, and their performance is not as good as traditional solar cells.

Thin-film solar modules are composed of glass substrates, metal layers, transparent conductive layers, electrical functional boxes, adhesive materials, semiconductor layers, etc. Organic-inorganic composite solar cells are solar cells based on the organic conjugated polymer-inorganic nanocrystalline composite material system. Because organic polymer materials have good film-forming properties, the energy level structure and band gap are easy to adjust, they can be prepared by wet methods. Low-cost, large-area, flexible solar cell devices and inorganic nanocrystalline materials with high stability, high mobility, and the ability to construct ordered nanostructures have become research hotspots in the field of solar cells in recent years. Metal nanoparticles can guide light into solar cells better and prevent light from escaping. In conventional "thick-film" solar cells, nanoparticles have little effect because all light absorption is through the film, which depends on its thickness. For thin films, however, nanoparticles can do a lot. Their scattering increases the time that light stays in the film, bringing the overall light absorption to a level comparable to conventional solar cells.

Aluminum and silver nanoparticles in the visible part of the spectrum do a good job of focusing light into solar cells. But the optical resonance also causes the nanoparticles to absorb light, which means the solar cell will be less efficient. The resonance of silver nanoparticles is just in the key absorption spectrum part of solar cells, so the absorption of light is considerable. Aluminum nanoparticles resonate beyond critical spectral parts for solar cells. The loss of energy is small. In addition, aluminum particles are easily passivated. Although the shape and size will change, the properties of the nanoparticles will change little after passivation. Nanoparticles have uneven surfaces that scatter light more into a broad-spectrum wavelength range. This results in greater absorption, which increases the overall efficiency of the cell.

Contents of the invention

The purpose of the present invention is to provide a fluorinated polyimide film for thin film solar cells and its preparation method, by using the film to be packaged on the surface of the light incident surface of flexible or thin film solar cells, the efficiency of flexible or thin film solar cells can be directly improved . And the encapsulated flexible or thin-film solar cell has the effect of self-cleaning.

To achieve the above object, the technical scheme adopted in the present invention is as follows:

The fluorinated polyimide film for thin film solar cells of the present invention is mainly made of the following components in parts by weight: fluorinated polyimide 100; nanometer aluminum powder 0.0001-0.1.

The fluorinated polyimide resin is obtained by introducing groups containing fluorine, silicon, phosphorus, or hydroxyl groups, or by introducing larger substituents (such as ring structures and other large side groups or 2 in biphenyl Substituents introduced at the 2′-position to produce non-coplanar structures) destroy a wide range of conjugation or bend macromolecular chains, introduce fats, especially alicyclic structural units, or use monomers that can bend the main chain (such as 3 , 4'- and 3,3'-dianhydrides, meta-substituted diamines) and other modified fluorinated polyimide resins.

For example, Chinese patents CN102504255A, CN1970603A, CN102558556A, CN1018183B disclose polyimide resins; or documents: 1. Yan Shanyin, etc., synthesis and characterization of novel pyridine ring-containing diamines and their soluble transparent fluorinated polyimides, synthetic Technology and application, 2010, No. 03, 5-12, 2. He Man et al., Preparation and nonlinear optical properties of fluorinated polyimide containing benzothiazole, polyimide disclosed in Acta Physicochemical Sinica, 2010, 26, 3073-3079 imide resin.

The preparation method of fluorinated polyimide film for thin film solar cell of the present invention comprises the following steps:

(1) Stir and blend the fluorinated polyimide resin and nano-aluminum powder with a stirrer at a temperature of -10~40°C;

(2) Import the above blend into the screw mixing extruder for blending and extrusion, the temperature is controlled at 220-290 ° C, the extruded product is filtered, metered and extruded, cast, cooled, understretched, drawn, and coiled to obtain a fluorinated polyimide film for solar energy encapsulation.

Beneficial effects of the invention: the nano metal aluminum particles are easy to passivate, although the shape and size will be changed, the properties of the nano particles change little after passivation. Nanoparticles have uneven surfaces that scatter light more into a broad-spectrum wavelength range. This results in greater absorption, which increases the overall efficiency of the cell. Scattering by the metallic aluminum nanoparticles increases the time that light stays in the film, bringing the overall light absorption to a level comparable to conventional solar cells.

The nano-aluminum powder modified fluorinated polyimide film we invented. The film can be used not only on the backlight plate of the thin film solar cell, but also on the surface of the light incident film of the thin film solar cell, and also can be used on the middle layer of the thin film solar cell. Compared with the unused thin film solar cell, the performance of the thin film solar cell modified by using the nanometer aluminum powder of the present invention is 3-15%. Metallic aluminum nanoparticles in the film can guide light into the solar cell better and prevent light from escaping. Solve the problem that in traditional "thick film" solar cells, nanoparticles have little effect and all light absorption must rely on thickness to solve the problem.

detailed description

Example 1

100 kg of fluorinated polyimide resin (Changchun Institute of Applied Chemistry) and 0.02 kg of nano-aluminum powder were stirred and blended evenly with a stirrer at a temperature of 10°C; the above blend was introduced into a screw mixing extruder for co-extrusion Mixed extrusion, the temperature is controlled at 285°C, the extrudate is filtered through a 180-mesh filter, metered extrusion (the pressure difference between the inlet and outlet of the metering pump is 2MPa), the cast film thickness is 50UM, 10°C air cooling, 4 times the drafting ratio Stretching, release paper coating, coiling and other processes to obtain hatching polyimide films for flexible or thin-film solar cells. The performance of the thin-film solar cell using the thin film is 3.6% higher than that of the unused thin-film solar cell.

Example 2

Mix 100 kg of fluorinated polyimide resin (Changchun Institute of Applied Chemistry) and 0.0001 kg of nano-aluminum powder with a stirrer at a temperature of -10°C; import the above blend into a screw mixing extruder for Blending and extrusion, the temperature is controlled at 220°C, the extrudate is filtered through a 180-mesh filter, metered extrusion (the pressure difference between the inlet and outlet of the metering pump is 2MPa), the cast film thickness is 50UM, air cooling at 10°C, and 4 times the drafting ratio Stretching, release paper coating, winding and other processes to obtain fluorinated polyimide film for flexible or thin film solar cells. The performance of the thin-film solar cell using the thin film is 14.9% higher than that of the unused thin-film solar cell.

Example 3

Mix 100 kg of fluorinated polyimide resin (Ningbo Jinshan Electronic Materials Co., Ltd.) and 0.1 kg of nano-aluminum powder with a stirrer at a temperature of 40°C; introduce the above blend into the screw for mixing and extrusion The extruder is used for blending extrusion, the temperature is controlled at 260°C, the extrudate is filtered through a 180-mesh filter, metered and extruded (the pressure difference between the inlet and outlet of the metering pump is 2MPa), the thickness of the cast film is 50UM, 10°C air cooling, 4 times the drag Elongation drawing, release paper coating, winding and other processes to obtain fluorinated polyimide film for flexible or thin film solar cells. The performance of the thin-film solar cell using the thin film is 8.9% higher than that of the unused thin-film solar cell.

Example 4

Mix 100 kg of fluorinated polyimide (Ningbo Jinshan Electronic Materials Co., Ltd.); 0.05 kg of nano-aluminum powder; 0.5 kg of cross-linking curing agent with a stirrer at 30°C; The material is introduced into a screw mixing extruder for blending and extrusion. The temperature is controlled at 295°C. The extruded product is filtered through a 180-mesh filter, metered and extruded (the pressure difference between the inlet and outlet of the metering pump is 2MPa), the thickness of the cast film is 50UM, and the temperature is 10°C. Air cooling, 4 times drafting ratio drawing, release paper coating, coiling and other processes to obtain fluorinated polyimide film for flexible or thin film solar cells. The performance of the thin-film solar cell using the thin film is 6.6% higher than that of the unused thin-film solar cell.

Claims (2)

1. A fluorinated polyimide film for thin-film solar cells, characterized in that: it mainly contains the following components in the following parts by weight to make: fluorinated polyimide 100; nanometer aluminum powder 0.0001-0.1; The fluorinated polyimide resin is introduced by introducing groups containing fluorine, silicon, phosphorus or hydroxyl groups or by introducing larger substituents to destroy a wide range of conjugation or to bend macromolecular chains, and introduce fatty structural units Or a modified fluorinated polyimide resin that uses a monomer capable of bending the main chain. 2. the preparation method of fluorinated polyimide film for thin-film solar cells as claimed in claim 1, is characterized in that: comprises the steps: (1) Stir and blend the fluorinated polyimide resin and nano-aluminum powder with a stirrer at a temperature of -10~40°C; (2) Import the above blend into the screw mixing extruder for blending and extrusion, the temperature is controlled at 220-290 ° C, the extruded product is filtered, metered and extruded, cast, cooled, understretched, drawn, and coiled to obtain a fluorinated polyimide film for solar energy encapsulation.