CN106257702A - Method to prevent moisture and oxygen from attacking perovskite absorber layer and prolong battery life - Google Patents

Abstract

The present invention proposes a method for preparing a battery device with extended life. Compared with the existing method of preparing a single absorption layer, the present invention uses multiple additives to form a nanostructured material with a high specific surface area, and uses several different packaging methods to achieve isolation of oxygen and water at room temperature. The present invention also proposes a preparation method using liquid gas, such as using dry protective gas such as nitrogen in a glove box to avoid interference from oxygen and moisture.

Description

Method to prevent moisture and oxygen from attacking perovskite absorber layer and prolong battery life

technical field

This new technology/technical invention belongs to the industry of methylammonium iodide lead perovskite solar photovoltaic cell device technology, and related technical manufacturing processes.

Background technique

The R&D and application of thin-film solar energy, including thin-film technologies such as cadmium telluride, amorphous silicon and copper indium gallium selenide, have been receiving attention based on their cost and technical advantages. Among them, cadmium telluride and copper indium gallium selenide, except for their cost In addition to their advantages, their conversion rate is also comparable to that of crystalline silicon.

Since 2009, methylammonium iodide lead organic/inorganic perovskite (CH3NH3PbI3, MALI for short) solar cells and their derivatives, due to its extremely high conversion rate and the use of extremely cheap solution coating preparation methods, make it a low-cost At the same time, due to the extremely long life of the carrier, it will not recombine before reaching the electrode terminal; in addition, the mobility of the negative electron is lower than that of the hole, and a titanium dioxide carrier is needed to accelerate its output. . From a practical point of view, perovskite is affected by atmospheric erosion and its lifetime. In MALI solar cells, the negative electron transfer layer needs a layer of porous titanium dioxide to expand its photon absorption area; in addition, it needs an unstable organic film, the hole transfer layer (HTL), to transfer the positive electrode; this layer of film requires This is done using expensive, high-purity organic thin films.

When considering applications such as solar farms, it is necessary to resist 30 years of temperature, humidity and oxygen erosion, especially the current preparation process of the hole transport layer (HTL), often found a large number of pinholes, these pinholes will be affected by air The moisture and oxygen penetration in the interior will damage the life of MALI ^3. At the same time, it is found that dry oxygen (dry oxygen) will decompose methylamine and lead iodide when exposed to sunlight, and will also corrode MALI ^4. It is necessary to adjust the organic methylamine ion to to deal with this problem. Therefore, in order to avoid the above-mentioned factors affecting the stability and service life of MALI batteries, it is necessary to avoid the influence of water vapor and oxygen in the atmosphere during the preparation of MALI batteries and subsequent use. However, for the packaged MALI cell, the moisture and gas in the atmosphere will still slowly permeate through the encapsulation material on the surface and bottom of the substrate, thereby degrading the performance of the perovskite film layer. Therefore, it is very important to remove moisture and oxygen in some feasible ways to prolong the service life of MALI batteries. Based on this, we can consider current technologies for removing oxygen from the atmosphere, although some of these technologies are based on heating. U.S. Patent ^5,6 uses silica-alumina zeolite molecular sieves to separate argon from oxygen. US Patent ⁸ proposes a method for removing oxygen from inert gases. It was also proposed to use lithium-containing organic resins to remove oxygen and other impurities in argon by utilizing lithium to react with oxygen to generate lithium oxides. In addition, for MALI batteries, we also need to avoid the influence of moisture, so special attention should be paid not to use the deoxygenation catalyst usually used in the catalytic water synthesis reaction process to avoid the generation of water vapor. In addition, activated carbon is also used to physically adsorb oxygen in the atmosphere due to its large specific surface area, which can effectively reduce the oxygen content from the original 10 ppm to 0.3 ppm.

Another approach is to use metals or metal catalysts to remove oxygen from the gas stream. These catalysts are commonly used to purify nitrogen, argon and carbon dioxide. It contains Cu-0226 S is cuprous oxide for high specific surface area spherical alumina catalysts. It is usually applied to remove trace oxygen in inert gases at room temperature. Up to 90% of oxygen can be eliminated at room temperature, which can be achieved by forming cuprous oxide from cuprous oxide.

For the same OLED technology, low moisture content (1000 ppm) conditions. U.S. Eastman Kodak patent 7,316,756 summarizes the types of desiccants that can be used. During the preparation process of some solar cells and the long-term use after encapsulation, a low-cost and effective method for removing oxygen and moisture is required. Removal of oxygen and water using fast reactions to avoid perovskite contact reactions with them is a feasible approach.

Contents of the invention

This patent proposes a method for preparing a long-life battery device, compared to the existing single method for preparing an absorbing layer. This patent uses a variety of additives to form nanostructure materials with high specific surface area, and uses several different encapsulation methods to realize the isolation of oxygen and water at room temperature. This patent also proposes a preparation method using liquid gas, such as using a dry protective gas such as nitrogen in a glove box to avoid the interference of oxygen and moisture.

To avoid perovskite cell performance being disturbed by moisture, metal-based getters commonly used in OLEDs can be considered. In addition, in order to avoid the perovskite battery being affected by oxygen, this patent uses sufficient materials that are easy to react with oxygen to reduce the concentration of oxygen, including nanomaterials with high specific surface area (square meter / kg), which can be used in the battery for a long time Efficient oxygen uptake over time and in areas of the battery that are susceptible to oxygen and moisture permeation (e.g. flexible seals instead of rigid seals in extreme temperature conditions).

Simply using materials that capture moisture in OLEDs in perovskite cells does not necessarily remove moisture effectively. For example, Na2O can absorb moisture but has no effect on oxygen absorption. On the contrary, the low price of nickel, iron and magnesium Oxides can absorb oxygen but not moisture. However, alkali metals partially covered by polymer resins can remove oxygen by forming oxides: 2Li + O ₂ = 2LiO2, and water by forming hydroxides: Li + 2H ₂ O = 2LiOH + H ₂ . But it must be ensured that these available purification materials are not completely occupied by oxygen or moisture. Therefore, in order to obtain the most efficient water and oxygen adsorption, the focus is on the selection and dosage of the purification material components. Usually the air contains about 20% oxygen by volume and a relatively small amount of moisture. For example, at 60°F and 50% relative humidity, the moisture volume ratio is about 0.87%. Then in this case, the adsorbed oxygen may consume all the amount of added adsorbent, and there is no extra space for adsorbing water (assuming that the adsorption process of water and oxygen is similar). Therefore, when water and oxygen exist at the same time, in order to obtain a good water and oxygen adsorption effect, the multi-component design of the purification material is necessary.

Other possible measures include the use of activated molecular sieves, which are based on adsorption into the tiny pores of aluminosilicates. The portable breathing device uses sodium 13X molecular sieve to absorb nitrogen and allow oxygen to pass through. Other types of molecular sieves are more used to absorb water. Therefore, the combination of these materials will protect battery devices from oxygen and moisture during production and operation. Several adsorbent materials are combined to quickly absorb oxygen and moisture to prevent them from damaging the perovskite, and also remove moisture and oxygen that penetrate into the battery through the sealing material during battery use. The method proposed in this patent can effectively remove the liquid or atmosphere that is in contact with various materials in each step of the perovskite battery manufacturing process. At the same time, after packaging, it can remove the liquid or atmosphere that gradually penetrates through the sealing device (heat or UV epoxy, etc.).

Description of drawings

Figure 1 is a schematic diagram of a typical perovskite solar cell. A conductive transparent electrode (2) such as indium tin oxide (ITO) or fluorine (FTO) is covered on a glass or polymer substrate (1). This layer can also be an electrode material with suitable conductivity and light transmittance, Then add a layer of porous material (3) such as titanium dioxide and aluminum oxide on the transparent electrode (2); next, add MALI (4) to the porous material (3). Then spin coat a hole transport layer (HTL) (5), such as Spiro-OMeTAD. Finally, a back electrode film layer (6), such as gold or silver, is added.

Figure 2 is a schematic diagram of a perovskite solar cell containing an adsorption material proposed in this patent:

(1) Top substrate, usually glass

(7) Bottom cover, usually glass

(8) All functional layers in the perovskite battery are the same as shown in Figure 1

(9) Equipment cavity

(10) Sealing device (contains a variety of optional absorbents)

(11) Absorbents installed in the cavity (such as coated on a flat metal belt)

(12) Absorbent coated on the rear cover

(13) Absorber coated on the back electrode

Figure 3 is a supplementary illustration of the deep cavity solar cell shown in Figure 2:

(14) glass frame

(15) Fusion-welded sealing glass frit

Detailed description

In order to facilitate the understanding of the present invention, specific details are set forth below. Of course, those skilled in the art need not use these specific details. The specific preparation process proposed by the present invention is applicable to any type of perovskite battery. First of all, this patent describes the preparation process of a basic perovskite battery, and can avoid the influence of the atmosphere on the battery.

Figure 1 shows a schematic diagram of a typical perovskite cell, and its numbering is consistent with the above.

The film thickness of transparent electrodes FTO and ITO is usually 0.2 microns, the thickness of porous titanium dioxide (TiO2) scaffold material is between 0.50 and 2 microns (a dense TiO2 layer of 0.06 microns can also be used to adjust the energy band), and perovskite is 0.3 microns, the HTL film layer is 0.3 microns, and the metal electrode thickness is 0.1 microns. The substrate (1) can be a suitable glass or polymer, such as soda glass.

At the same time, porous TiO2 can adsorb oxygen and water during the preparation of battery devices. Also add enough absorbent to remove water and air. Also, as a precautionary measure, the titania-coated substrate can be heated to around 120°C in vacuum or nitrogen, and the oxygen and water attached to the pores can be flushed out with a pump/nitrogen.

In the following, MALI usually means methylamine lead iodide (CH3NH3 PbI3) and its derivatives batteries, including some organic functional groups (R.NH3.PbI3, HC(NH2)2 PbI3), or tin (Sn), tungsten (W) partially or completely replace lead (Pb). Likewise, iodine is partially or completely replaced with other halide ions such as chlorine (CL), bromine (Br) and fluorine (F). Also included are perovskite cells doped with small amounts of trivalent metals such as boron (B), aluminum (Al), gallium (Ga), and indium (In).

Printed metal electrodes or other conductive materials can be used to enhance the conductivity of the transparent planar electrodes of a single cell, where the single cell is the small cell of the overall structure of the CIGS solar cell familiar to the skilled person. At the same time, no matter what preparation method is used, high-purity materials are required to avoid defects.

Finally, the back electrode can be any suitable thin film or nanoparticle conductor, including metals, carbon, carbon nanotubes, and graphene. Solid metal or foil can be either rigid or flexible.

In order to avoid the influence of the atmosphere on the battery, a variety of desiccants and oxygen getters are combined in the method shown in Figure 2:

1) In the cavity (9), the metal strip (11) is used to prepare the front substrate and the bottom plate of the solar cell.

2) As a layer of film (12) on the inside of the back cover

3) or a thin film covering the back electrode (13)

4) As in the previous case presented in US Patent 13, sealant (10) on the edge between the two boards.

5) Prioritize any combination of the above that can ensure long battery life

These absorbents can be placed on one or more sites taking into account demand, service life, cost, equipment tightness, thickness and width. However, in order to obtain the highest effect, a film layer with a high specific surface area is applied to the inner surface of the rear cover, as is the coating of the rear electrode.

In addition, the coating of the back electrode must not affect the electrode, and the coating on the metal strip in the chamber should be prepared to avoid short circuits. Adding too much absorbent will affect the sealing, and too little will affect the adsorption capacity.

Claims (8)

1. can pay the utmost attention to coat film layer inside back-cover plate, as being directly coated with above-mentioned water and the absorbing material of oxygen；According to absorption water and the difference of oxygen, the zones of different in seal base selects specific material；Active metal can react with oxygen and water, but metal protoxide is easier to react with oxygen；Can the thickness of coating depend on the thickness of gasket seal in benefit, expense, service life, coating process, cavity and use in other positions, the thickness of coating between 0.5 to 1000 micron, preferably 700 microns；Possible material includes lower valency metal-oxide, it can aoxidize the most further, such as Red copper oxide (Cu2O), manganese oxide (MnO), the granule that 637106 series are 50-100 nanometer that lower valency barium oxide such as V2O3 or VO2, iron oxides Fe3O4(such as Sigma-Aldrich provides)；Preferably there is high specific surface area and the nano-sized particles of minimum weight ratio, it is ensured that can fully adsorb water and oxygen, simultaneously considering cost；SAES getter uses adds calcium oxide as dry binder (but this needs about 200 DEG C solidifications) in silicon；Additionally SAES getter also use nano zeolite as the ZeoTec of its 100nm narrow size distribution, such as LTA Na(4A)；Powdered-metal can be continuing with water and oxygen reaction, and as at fluoropolymer resin lithium or calcium, the size of these materials mostly is nano level；In the case of not affecting adhesive force, the ratio of granule and the volume of polymeric binder should be the highest, should try one's best close to 50% for thicker coating, so that oxygen and water can be by polymeric binder and adsorb on absorbent；Coating can be passed through the techniques such as dip-coating, spraying, electrophoresis, ink-jet, aerosol, scraper, silk screen printing, subsider and make.

2. select suitable binding agent (including epoxy resin), the metal tape in cavity is fixed on back shroud；These include deicer and SAES getter, and are coated with the oxygen absorbent of the metal-oxide of last layer the above-mentioned type, preferably nano-particle；These adsorbents are prone to be converted into the oxide of more expensive state under room temperature aerobic environment, such as resin Red copper oxide or lithium metal；It addition, multiple thin metal tape can be added, some is oxygen absorber, and some is water absorbing agent；SAES getter is non-evaporation type getter, it means that they form water thin film not against evaporation and adsorb in equipment inner wall (the traditional barium agent etc. as on vacuum valve and cathode ray tube)；But, even if being that non-evaporation type getter is also required to be heated to 300～600 DEG C of long durations that coexist with reacting metal and could activate；This is the most difficult for solaode, and therefore, additive method may be advantageously；For OLED, SAES getter also has dry, flexible product, and calcium oxide is added on the polymer coating metal tape that thickness is 50-80 micron, and these are it is also contemplated that be contained on the back shroud of solaode.

3. the absorbing material of above-mentioned oxygen and water is coated on the glass prebasal plate of sealing；But, under 1000 ppm concentration, the effect of some getteies cannot well play, if the amount of getter is not enough, may result in the dusty gas of input more than this problem of absorbent gas；Above-mentioned getter includes molecular sieve, metal-oxide, alkali metal oxide, sulfate, metal halide and perchlorate；Patent proposes a greater variety of getter, contributes to solving the problems referred to above；In like manner considering desiccant and special oxygen getter, the width carrying thermoplastic belt based on sealed binder, such as PVS 101 polyisobutylene (PIB) is between 9 to 10 millimeters, and thickness is between 0.20 to 0.55 millimeter；At a pressure sufficient, PIB belt edge is locally heated to 140-160 DEG C and can produce certain deformation；In general, thicker sealant is the thickest, allows that the moisture of infiltration is more；Being equally useful mixing water and the liquid adhesive of oxygen absorbing material, weight is about 30% to 80%；Such as, the 10-3008 type epoxy resin of Epoxies.com is flexible adhesive, it is easier to resist thermal expansion expected from glass substrate during outdoor solar panel is installed and used；Additionally, it can be placed one hour at 82 DEG C, this is sufficient for the preparation requirement of perovskite battery；The filler of this adhesive has certain space, arranges for THICKNESS CONTROL and film layer any direction；Patent is important to note that, flexible adhesive sealant is the biggest to the permeability of steam, and the effect of the adsorbent containing enough nano-particle is the most obvious.

4. it is coated with the back electrode of the absorbing material of above-mentioned oxygen and water；It is important that the existing electrode coating potentially including polymer or resin silver particles can not be destroyed, accordingly, it would be desirable to select a resin being not easily dissolved Argent grain or the absorbent of fluoropolymer resin；Equally, vacuum or splash-proofing sputtering metal back electrode need coat one layer of absorbed layer；But, some desiccant being mentioned and oxygen absorbing material may be with the reactions (such as silver, aluminum) of some back electrode of solar cell metals；For above reason, preferred embodiment is coating layer of material inside back shroud.

5., in equipment cavity, use mechanical or gluing method that the absorbing material of above-mentioned oxygen and water is coated in narrow metal tape, the backboard plane with it as right angle and base plan；Therefore, during molecular sieve joins nano cuprous oxide crushed into powder the glove box of inflated with nitrogen；This composite is coated on the nanometer silver back electrode of meeting oxygen permeable and water；It should be noted that the adsorbing material coating high-specific surface area at a large substrates and Panel area, it can be ensured that absorb oxygen and the water of q.s.

6. add Red copper oxide (Cu2O) nano-particle, and the nano-particle of absorption water, such as poriferous titanium dioxide (TiO2) or aluminium oxide (Al2O3), glass covers fluorine tin oxide (FTO) electrode of electrically conducting transparent；Need exist for filling up some porous TiO2 absorbing materials.

7. these perovskite batteries are produced by solution crystal process；These liquid need deoxidation as far as possible, such as logical nitrogen bubble or evacuation；The liquid of these degassings should process in nitrogen glove box；Use 5X molecular sieve, heat-activated, and in perovskite spin coating solvents butyrolactone and dimethyl sulfoxide to guarantee to absorb water；Add molecular sieve can overnight water and precipitate be filtered to isolate；Claim nine: cavity filled by copper-indium-galliun-selenium film solar cell resin；This suppression steam diffusion at solar panels both sides sealing further；But, some resin materials may produce adverse effect to solar battery thin film；In the case of other thin-film solar cells, vinyl fills up the space between cover plate and base plate glass sheet, it is provided that the seal edge thickness (between 0.4-0.5 millimeter) of resin sheet be slightly thinner than the thickness (0.55 millimeter) of PIB；Trosifol or Tectrosol resin can be selected；The EVA plate resin of E.I.Du Pont Company's supply has been used for above silicon solar cell；The most also supply poly-butanoic acid (PVB), such as its PV5200；The sealing device not having potting resin can resist more water and oxygen, and therefore the use of nano-particle can capture water and oxygen, so that catching water and oxygen with nano-particle；Major part is used alternatingly and covers the polymer barrier thin film of antiseepage inorganic coating；These are all preferentially used in the OLEDs of flexible water-sensitive, can be from Vitex It is commercially available with companies such as Nagasse；Refer to the academic research of A Ra Cho14；The device that is bonded and sealed can provide bigger cavity volume not increase its thickness to fill more getter；As it is shown on figure 3, before glass cover seals solar cell substrate, use melt-glass powder seal glass cover peripheral；This sealing does not penetrates into water and oxygen；Increase cross-sectional area and thickness can overcome organic bond to seal the problem permeated；But, the increase of thickness makes cavity volume also increase, and can reach getter capacity by increasing getter；Suitable glass frit powder can be obtained, including Asahi Glass from multiple suppliers；Its product includes lead-free glass powder, as its type of Bi2O3 ZnO(has 9079-15 and ASF2511C), it needs to burn 10 minutes to reach sealing effectiveness at about 470 DEG C；Another be SnO-P2O5(type be FF-67), need at 480 DEG C burn 10 minutes)；Use this instrument bezel greatly to add the packing volume of absorbing material, sealing device can be maintained to be dried a lot of years with under anaerobic state；The thickness of framework is between 2 to 3 millimeters, and width is between 5 to 15 millimeters, so bonding agent is also required to similar size with glass frit sealing equipment；Therefore, the multi-layer absorbent material that 3 millimeter are thick can leave bigger space, although based on absorbing particles kind and the selection of size, 0.7-1.3 millimeter may be the most applicable；Flat faced display, liquid crystal display screen, vacuum fluorescent lamp and gas discharge display in early days organic binder bond in all contain low temperature lead-borate glass pearl；Glimmering glass plate, cathode ray tube bulb sealing device in must contain glass dust；Instrument bezel is not only single sheet frame, it is possible to be four bar shapeds or shaft-like glass；Select further circle, square or rectangle sodium calcium glass tubing to replace bar shaped soda-lime glass, these all can that be taken in several suppliers (including Good fellow).

8. alternate version is to use formed glass, punching press or the back-cover plate of forming metal, is with a suitable protruding framework outside it；The thermal expansion coefficient difference of metal and flexible adhesive need to be considered；Along with getter and the increase of desiccant usage amount in deep chamber, relative to rigidity position, sealant needs to overcome gas and the water of more infiltration from air；It is used together said one or multiple claim can make absorbent play maximum effect for many years；The thin-film solar cells of water and oxygen absorbent is used to have the life-span of overlength, such as CIGS and copper-zinc-tin-sulfur battery at diverse location.