CN110337423A

CN110337423A - Low etching and contactless glass for conductive paste composition

Info

Publication number: CN110337423A
Application number: CN201780087366.9A
Authority: CN
Inventors: D·拉斯卡尔; 翟光; G·舒尔茨; Y·杨; M·卡曾戴斯·德达施提
Original assignee: Heraeus Precious Metals North America Conshohocken LLC
Current assignee: Heraeus Precious Metals North America Conshohocken LLC
Priority date: 2017-03-24
Filing date: 2017-03-24
Publication date: 2019-10-15
Also published as: WO2018174898A1; TWI662560B; TW201835942A

Abstract

The present invention relates to a kind of conductive paste compositions with reduced etch features.The conductive paste composition includes metallic, at least one frit and organic vehicle.At least one frit is free from lead, and including with 100% total weight of at least one frit at least about SiO of 65-95wt%₂、B₂O₃And Bi₂O₃, at least one basic anhydride of about 5-20wt% and the molybdenum oxide of about 3-10wt%.

Description

Low etching and contactless glass for conductive paste composition

Technical field

The present invention relates to the frits for conductive paste composition.In one aspect, glass composition has suitable for double Or low etching and contactless shaping properties in conductive paste composition used in dual printing application.On the other hand, frit It can be used for the back side welding piece in conductive paste composition to be used to form in passivation emitter-base bandgap grading back side solar battery.

Background technique

Solar battery is the device that luminous energy is converted to electricity using photovoltaic effect.Solar energy is attractive green energy Source is measured, because it is sustainable and only generates pollution-free by-product.In operation, when solar battery in light emission, A part of incident light is by surface reflection and remainder transmits in solar battery.The photon of transmitted light is inhaled by solar battery It receives, the solar battery is usually made of the semiconductor material of such as silicon.Energy from absorbed photons is from semiconductor material Atomic excitation its electronics, to generate electron-hole pair.These subsequent electron-hole pairs are separated by p-n junction and by applying The conductive electrode in solar cell surface is added on to collect.By this method, electricity can between the solar battery of interconnection into Row conduction.

Solar battery can have a variety of different structures.Conventional solar battery, which has, is applied to semiconductor substrate The anti-reflection coating (ARC) of front side is to reduce the reflection of incident light.It will be usually applied to by the front side electrode that conductive paste is formed On top in the anti-reflection coating of grid-like pattern.Another conductive paste (it can be identical or different with front-side conductive cream) is applied Solar battery back side is added on to form backside electrode/welding piece.Then aluminium cream is applied to substrate backside, weld piece The back surface field of solar cell properties is improved to be formed in edge.

The specific conductive paste composition for deploying these the various components for being used to form solar battery for it especially to apply Add.Conventional conductive composition contains metallic, inorganic component and organic vehicle.It is used to form on front side of front side electrode and leads Electric composite cream is designed to have good etching and contact formed features so that its is etchable across such as anti-reflecting layer Front side layer layer and while realize and the contact at back lining bottom.

The conductive paste for being used to form front side electrode is usually applied at comb mesh pattern by solar battery by screen painting Front surface, the comb mesh pattern is by thin and parallel thin grid line (finger line) and wider with thin grid line square crossing Main gate line (busbar) (at least two) formation.In one approach, such as International Patent Application Publication WO 2010/135496 Method disclosed in number, before thin grid line can pass through dual printing so that the thin grid line of first layer is printed on solar battery On surface, and it is printed on the second layer thin grid line on the top of the thin grid line of first layer.Other the methods are disclosed in Such as in U.S. Patent Application Publication No. No. 2012/0180862 and U.S. Patent No. 9,224,888.Have been displayed it is described double or Dual printing technology improves the efficiency of gained solar battery.

In double or dual printing technology, for printing the conductive paste of the thin grid line of first layer and/or main gate line preferably not It is same as the conductive paste for printing the thin grid line of the second layer and/or main gate line.There are the feelings of dual printing solar cell structure Under condition, should carefully deploy the frit in the conductive paste for being present in and forming the thin grid line of the second layer and/or main gate line so as to such as The solar cell substrate material of anti-reflecting layer has limited chemical reactivity or does not have chemical reactivity to avoid that is damaged A little layers.This reduces the loss of the generation and open-circuit voltage (Voc) that shunt in solar battery, improves solar battery in turn Efficiency.

Different types of solar battery is the solar battery for being passivated emitter-base bandgap grading back side battery or " PERC ".It is conventional too In positive energy battery, aluminium cream is directly applied to solar cell substrate back surface to form back surface field.In PERC solar-electricity Chi Zhong usually will be applied to substrate back surface by the backside passivation layer that the dielectric material of such as aluminum oxide is formed first.It can incite somebody to action As the additional back layer of silicon nitride the cover layer is applied on the top of backside passivation layer.Then, partial rear passivation layer is removed The region of underlying substrate is exposed with additional back layer.The step for can be realized for example, by acid etching or laser drill. Then aluminium conductive paste is applied on the top of back layer, " hole " generated during being thus filled in removal process.At these In region, local back surface field is formed when roasting aluminium cream.Back side welding piece can be applied before or after applying aluminium cream In on back surface.Description standard solar battery and exemplary PERC solar battery in Fig. 1 and 2.PERC solar energy has been displayed Battery has the efficiency improved compared to the solar battery for not having backside passivation layer.

Be used to form the back side welding piece on PERC battery conductive paste must also with such as backside passivation layer and back side the cover The bottom of layer has limited chemical reactivity or without chemical reactivity to avoid damaging those layers, and the damage causes too The electric property of positive energy battery reduces.

Contactless forming and low etching glass are known in fields.However, lacking the glass of these a variety of types Glass, because needing relatively high maturing temperature during processing due to its chemical composition, the temperature is not suitable for It is used together with the conventional solar battery of certain type with PERC solar battery.Furthermore, it is necessary to contactless glass tune The improvement for the electric property in conductive paste matched.

Therefore, in mackle brush solar battery structure and PERC solar battery, need include have it is low etching and it is non- The electrically conductive composition of the frit of contact shaping properties, the frit can roast and change at relatively low temperature Into the electric property of gained conductive paste.

Summary of the invention

In one aspect, the present invention provides a kind of conduction including metallic, at least one frit and organic vehicle Composite cream.At least one frit is free from lead, and includes at least with 100% total weight of at least one frit Total amount is the SiO of about 65-95wt%₂、B₂O₃And Bi₂O₃, about 5-20wt% at least one basic anhydride and about 3-10wt% MoO₃。

The present invention further relates to a kind of method for preparing passivation emitter-base bandgap grading back side solar battery comprising following steps: Back side conductive paste is applied thereto on the back side for being formed with the silicon substrate of at least one backside passivation layer, the backside passivation layer In be formed with multiple openings to expose the region of silicon substrate, apply aluminium conductive paste in the opening of passivation layer overleaf to contact silicon lining Bottom, and heating silicon substrate.Back side conductive paste includes the cream of invention disclosed herein.

Another aspect of the present invention relates to a kind of passivation emitter-base bandgap grading back side solar batteries comprising has front surface and back table The silicon substrate in face, is formed in back at the backside passivation layer on silicon substrate back surface with multiple openings formed therein Aluminium in the opening of face passivation layer is carried on the back contact, is on silicon substrate back surface by what conductive paste composition disclosed herein was formed At least one back side welding piece and the preceding gate electrode that is formed in silicon substrate front surface.

The present invention is also about a kind of method for forming solar battery comprising following steps: the first conductive paste is printed To form first group of electrode on to silicon substrate front surface, the second conductive paste is printed on the top of the first conductive paste to form Two groups of electrodes, and heating silicon substrate.First conductive paste is different from the second conductive paste, and the second conductive paste includes that this paper institute is public The cream of the invention opened.

The present invention further provides a kind of solar batteries comprising has the silicon for the anti-reflection coating for being applied to its surface Substrate, first group of electrode being formed directly into anti-reflection coating and second group of electrode being formed in first group of top of electrodes, Wherein second group of electrode is formed by conductive paste composition disclosed herein.

Detailed description of the invention

When considered in conjunction with the accompanying drawings, more complete evaluation of the invention and its many adjoint advantage are readily able to obtain, this be by Become being best understood from by reference to following specific embodiments in it, in the accompanying drawings:

Fig. 1 is the side cross-sectional view of standard solar cells；

Fig. 2 is the side cross-sectional view of PERC solar battery；

Fig. 3 A-3D is for using on front side of the conductive paste composition of the embodiment of the present invention formed on conventional solar battery The top view of various double printing processes of electrode；And

Fig. 4 is the top view for the double printing processes being used together with the conductive paste composition of the embodiment of the present invention.

Specific embodiment

The conductive paste for being used to form electrode of solar battery generally includes conductive metal particles, one or more frits, has Machine mediator and one or more optional additives.As set forth herein, it is special to show low etching upon firing for frit of the invention Thus sign improves double printing solar cells or PERC solar energy so that its damage of reduction to the bottom surface layer on substrate Solar cell properties in battery.

Frit

In the conductive paste for being used to form front side electrode of solar battery, frit serves as adhesion power media, promotes conductive Bonding between particle and silicon substrate, and therefore good electric contact therebetween is provided.Specifically, after baking, conventional Frit be etched through the superficial layer (such as anti-reflecting layer) of silicon substrate so that can make between conductive paste and silicon wafer At effective electric contact.

With traditional role of the frit used in conductive paste composition on the contrary, frit of the invention is designed to open up The etch features of existing bottom line.Such frit is especially suitable in double printing applications and suitable for forming PERC solar energy Back side welding piece on battery.Specifically, frit described herein is presented in during solar battery roasts to bottom The bottom line of superficial layer etches, this makes those that will be otherwise caused to shunt and open-circuit voltage loss and therefore in turn Reduce being preferably minimized to the damage of bottom for solar battery efficiency.In this way, frit of the invention be designed to it is low etching and Contactless molding glass.

In one embodiment, one or more frits of the invention preferably have low lead content or without lead, because Known lead has strong etching property for the superficial layer on solar battery.As set forth herein, with 100% gross weight of frit Meter, term " low lead content " refer to that lead content is at least 0.5wt% and less than about 5wt%, such as less than about 4wt%, are less than The frit of about 3wt%, less than about 2wt%, less than about 1wt% and less than about 0.8wt%.As set forth herein, with frit 100% total weight, term " be free of lead " refers to lead content less than about 0.5wt%, preferably less than about 0.4wt%, more excellent Selection of land less than about 0.3wt%, the even more preferably less than about frit of 0.2wt% and most preferably less than about 0.1wt% lead.? In one most preferred embodiment, frit includes less than about 0.01wt% lead, can be from the attached of other glass ingredients Form with impurity exists.In a preferred embodiment, glass composition does not include any lead intentionally added.

In one aspect of the invention, frit preferably includes the silica (SiO of relatively high total content₂), three oxygen Change two boron (B₂O₃) and bismuth oxide (Bi₂O₃).These oxides generally act as glass forming oxide.In one embodiment, with 100% total weight of frit, frit are included in about 40 to about 70wt% and preferably about 40 to about 65wt% model Enclose interior SiO₂.In still another embodiment, with 100% total weight of frit, frit includes about 40 to about 50wt% SiO₂Or alternatively about 55 to about 65wt%SiO₂。

In addition, frit includes about 1 to about 30wt%, preferably about 5 to about with 100% total weight of frit 25wt%B₂O₃.In one embodiment, with 100% total weight of frit, frit may include about 5 to about 20wt%, Preferably about 5 to about 10wt%B₂O₃.Alternatively, frit may include about 15 to about 20wt%B₂O₃。

With 100% total weight of frit, frit further includes about 5 to about 30wt%, preferably about 5 to about 25wt% and more preferably about 10 to about 25wt%Bi₂O₃.In another embodiment, with 100% total weight of frit, Frit may include about 10 to about 15wt%Bi₂O₃Or about 15 to about 25wt%Bi₂O₃。

SiO with 100% total weight of frit, in frit₂、B₂O₃And Bi₂O₃Total content preferably at least 65wt% and no more than about 95wt%.SiO₂、B₂O₃And Bi₂O₃Total content be preferably at least 70wt% and no more than about 90wt%.

In addition, frit preferably includes at least one basic anhydride, such as (e.g.) Na₂O、Li₂O or K₂O.These alkali Property oxide generally act as and reduce chemically reactive glass modifier of the frit under increasing firing temperature.Frit is preferred Ground includes at least two combination in these basic anhydride, such as Na₂O and Li₂O.In one embodiment, with frit 100% total weight, frit include at least about 4wt%, the total alkaline oxide of preferably at least about 5wt%.Meanwhile with glass 100% total weight of material, frit include no more than about 20wt%, preferably no more than about 10wt% and most preferably not More than about 8wt% basic anhydride.In an alternative embodiment, frit includes the total alkaline oxide of about 16-20wt%.

Other than basic anhydride, frit can also include zinc oxide (ZnO).If frit includes ZnO, with 100% total weight of frit, to be no more than 15wt%, preferably no more than 12wt% and most preferably be no more than The amount of 10wt% exists.

In addition, frit of the invention further includes molybdenum oxide (such as MoO₃), niobium oxide (such as Nb₂O₅), alumina At least one of object, oxysulfide, seleno oxide, tellurium oxide, barium oxide and tungsten oxide.In one embodiment, With 100% total weight of frit, frit preferably includes at least about 2wt%, preferably at least about 3wt% and more excellent Selection of land at least about 4wt%MoO₃.In another embodiment, frit includes no more than about 15wt%MoO₃And do not surpass preferably Cross about 10wt%MoO₃.In one embodiment, frit includes no more than about 9wt%MoO₃.If it is present frit packet Include less than about 2wt%Nb₂O₅。

According to one embodiment, with 100% total weight of each of these components, (SiO₂+B₂O₃+Bi₂O₃) Content and (MoO₃+Nb₂O₅) the weight ratio of total content be at least about 8 and no more than about 25.

In still another embodiment, with 100% total weight of each of these components, ((SiO₂+B₂O₃+Bi₂O₃) +(MoO₃+Nb₂O₅)) it with the weight ratio of (basic anhydride+ZnO) is at least about 4 and preferably no more than about 18.

Frit may include the compound and/or its mixture of generation oxide after other elements, oxide, heating. In one embodiment, frit may include other oxides or compound known to those skilled in the art, including But be not limited to magnesium, titanium, zirconium, nickel, gadolinium, antimony, cerium, zirconium, titanium, manganese, tin, ruthenium, cobalt, iron, copper, germanium, indium, alkaline-earth metal, rare earth metal, Phosphorus and chromium or its at least two any combination, compound or aforementioned metal that those metal oxides can be generated after baking In at least two mixture, at least two mixture in aforesaid oxides, can roasting when generate those metals At least two mixture in the aforesaid compound of oxide or two kinds are referred to above any mixed more than two kinds Close object.

Preferred frit of the invention is amorphous or partially crystallizable shape solid the powder for showing glass transfer.Glass turns Move temperature T_gIt is temperature when amorphous material is converted into part flowing subcooling films from rigid solid after the heating.Of the invention Another important feature of frit is glass softening point, is usually less than glass transition temperature and identifies more than a certain arbitrary point Glass start softening when point.Method for measuring glass transition temperature and glass transition temperature is the technology of fields Known to personnel.Specifically, DSC equipment SDT Q600 (being purchased from TA Instruments) can be used to measure glass Transition temperature T_g, while recording Differential Scanning Calorimetry measurement (DSC) and thermogravimetric analysis (TGA) curve.The instrument and equipment have water Average weighing apparatus and the boiler with platinum/platinum-rhodium (R type) thermocouple.Sample used holder is the oxidation that capacity is about 40-90 μ l Aluminium ceramic crucible.In order to measure and data assessment, Survey Software Q Advantage is applied respectively；Thermal Advantage Release 5.4.0 and Universal Analysis 2000, edition 4 .5A Build 4.5.0.5.As for reference disk and sample Product disk, the aluminum pan for the use of volume being about 85 μ l.The sample of the amount of about 10-50mg is weighed into sample disc, and accuracy For 0.01mg.Empty reference disk and sample disc are placed in a device, baking oven is closed and start to measure.From 25 DEG C of starting temperature It spends to 1000 DEG C of end temperature, using the rate of heat addition of 10K/min.Always nitrogen (N is used₂5.0) balance in instrument is purged Device, and with synthesis of air (80%N₂And 20%O₂, come from Linde) and purging baking oven, and flow rate is 50ml/min.Make The first step in DSC signal, is evaluated as glass transfer with software described above, and the initial value measured is regarded For T_gTemperature.

T_gIt is preferably lower than the required maturing temperature of conductive paste., according to the invention it is preferred to the T of frit_gIt is at least about 400 ℃.Likewise it is preferred that the T of frit_gNo more than about 900 DEG C, preferably no more than about 800 DEG C and most preferably no more than about 700℃.In addition, in one embodiment, the glass softening point of glass is about 400-550 DEG C, more preferably about 480-530 DEG C. In another embodiment, the glass softening point of glass is about 650-800 DEG C, preferably about 690-760 DEG C.

Those skilled in the art's known glass frit particle can show various shape, size and surface area and volume Than.As discussed herein, the same or similar shape of shape that glass particle can show and can be showed by conductive metal particles Shape (including length: width: thickness ratio).Advantageously improve the electrical contact of made mfg. electrode has a kind of shape or various shapes Combined frit particles are preferred.Preferably, the median particle diameter d of frit particles₅₀(such as above in relation to conductive metal grain Son is illustrated) it is at least about 0.1 μm.Meanwhile the d of frit₅₀Preferably no more than about 10 μm, no more than about 5 μ M and most preferably no more than about 2.5 μm.In one embodiment, the specific surface area of frit particles is at least about 0.5m²/ G, preferably at least about 1m²/ g and most preferably at least about 2m²/g.Meanwhile specific surface area is preferably no more than about 15m²/g、 Preferably no more than about 10m²/g。

According to another embodiment, frit particles may include surface covering.Known in fields and it is considered as suitable It may be used to frit particles together in any coating of the context of the invention.Preferred coatings of the invention include those rush Improved coating is contacted with conductive paste in organic vehicle into glass dispersible.If this type coating exists, in each case With the total weight of frit particles, coating preferably corresponds to no more than about 10wt%, preferably no more than about 8wt%, most Preferably no more than about 5wt%.

With 100% total weight of cream, conductive paste includes at least about 0.5wt%, preferably at least about 1wt% and optimal Selection of land at least about 2wt% frit.Meanwhile with 100% total weight of conductive paste, cream is preferably included no more than about 10wt%, preferably no more than about 8wt%, no more than about 6wt% and most preferably no more than about 5wt% glass Material.

Conductive metal particles

Electrically conductive composition also includes conductive metal particles.Preferred conductive metal particles are that those show optimal conductivity simultaneously And it is effectively sintered in roasting so that it generates the conductive metal particles with the electrode of high conductivity.Suitable for forming solar energy Known conductive metal particles are preferred in the fields of battery electrode.Preferred metallic includes but is not limited to element Metal, alloy, metal derivative, the mixture of at least two metals, the mixture of at least two alloys or at least one metal With the mixture of at least one alloy.

In one embodiment of the invention, with 100% total weight of cream, conductive paste be may include at least about 30wt%, preferably at least about 35wt%, more preferably at least about 40wt%, more preferably at least about 45wt% and most preferably Ground at least about 50wt% metallic.In a preferred embodiment, with 100% total weight of cream, conductive paste includes extremely Few about 55wt% metallic.Meanwhile with 100% total weight of composite cream, conductive paste is preferably included no more than about 99wt%, preferably no more than about 95wt%, no more than about 90wt%, no more than about 85wt%, more Preferably no more than about 80wt%, no more than about 75wt%, no more than about 70wt% and more preferably Ground no more than about 65wt% metallic.In a preferred embodiment, conductive with 100% total weight of composite cream Cream includes no more than about 60wt%.Conductive paste with this conductive metal particles content suitable for double printing technologies, as with In the thin grid line in formation second layer front side and/or it is used to form front side main gate line and is used to form back side on PERC solar battery The conductive paste of welding piece.

The metal that may be used as metallic includes at least one of silver, copper, gold, aluminium, nickel, platinum, palladium, molybdenum and its mixing Object or alloy.In a preferred embodiment, metallic is silver.Silver can be with elemental silver, silver alloy or silver-colored derivative Form exists.Suitable silver derivative includes such as silver alloy and/or silver salt, such as silver halide (such as silver chlorate), silver oxide, nitre Sour silver, silver acetate, silver trifluoroacetate, silver orthophosphate and a combination thereof.In another embodiment, metallic, which may include, is coated with one Or the metal or alloy of a variety of different metals or alloy, such as be coated with the silver particles of aluminium or be coated with the copper particle of silver.

Metallic can exist together with organic or inorganic surface covering.Known in fields and it is deemed appropriate to It may be used to metallic in any coating of the context of the invention.Preferred organic coating is that those promotions are dispensed into Coating in organic vehicle.Preferred inorganic coating is that those adjust the painting for being sintered and promoting the adhesive performance of gained conductive paste Layer.If this type coating exists, with 100% total weight of metallic, coating is preferably corresponded to no more than about 5wt%, preferably no more than about 2wt% and most preferably no more than about 1wt%.

Conducting particles can show various shape, size and specific surface area.Some examples of shape include but is not limited to ball It is shape, angular, elongated (bar or needle-shaped) and flat (sheet).Conductive metal particles can also be with the group with particle of different shapes Conjunction form exists, the such as (e.g.) combination of spherical metallic particles and piece shape metallic.

Another feature of metallic particles is its average particle size d₅₀。d₅₀It is the median of median diameter or size distribution.It is Particle size values under 50% cumulative distribution.Size distribution can via laser diffraction, dynamic light scattering, imaging, electrophoretic light scattering or Known any other method measures in fields.Specifically, the present invention is measured according to ISO 13317-3:2001 Granularity.As set forth herein, using the Horiba LA-910 laser diffraction for being connected to the computer with LA-910 software program Particle size analyzer measures median particle diameter.The relative index of refraction of metallic is selected from LA-910 handbook and Input Software program In.Test chamber is filled on storage tank with deionized water and is suitably filled with line.Then by using in software program circulation and Agitation function recycles solution.After one minute, solution is drained.This process is additionally repeated once to ensure in chamber without any residual Remaining material.Then third time and recycles it and stirs one minute deionized water filled chamber.Any background in solution Particle is eliminated by using the blank function in software.Then start ultrasonic agitation, and metallic is slowly added Until being in appropriate area in software program until transmissivity item in solution into test chamber.Once transmissivity is in proper Work as degree, carry out laser diffraction analysis and measures the size distribution of metal component and with d₅₀Form provide.

The median particle diameter d of metallic₅₀Preferably at least about 0.1 μm and preferably at least about 0.5 μm.Meanwhile d₅₀ Preferably no more than about 5 μm and no more than about 4 μm.In one embodiment, conductive paste composition includes spherical shape The combination of silver particles and piece shape silver particles, wherein the d of spherical silver particles₅₀Preferably less than or equal to about 3 μm, and piece shape silver granuel The d of son₅₀Preferably less than or equal to about 5 μm.

The another way of the shape and surface that characterize particle is characterized by its specific surface area.Specific surface area is solid Property, equal to the total surface area or sectional area of per unit mass material, solid or total volume.It is (single divided by quality by surface area Position is m²/ g) or surface area divided by volume (unit m^-1) Lai Dingyi.Specific surface area can pass through cloth known in fields E Te (BET, Brunauer-Emmett-Teller) method measures.As set forth herein, according to DIN ISO 9277:1995 into Row BET measurement.Use the Monosorb model according to SMART method (adsorption method with adaptive ingredient rate) operation MS-22 instrument (being manufactured by Quantachrome Instruments) measures.Use aluminium oxide (surface area reference material Catalog number (Cat.No.) 2003 is purchased from Quantachrome Instruments) it is used as reference material.Sample is prepared in in-building type It is analyzed in degasification platform.Flowing gas (30%N₂And 70%He) impurity is swept, generate the clean table that may occur in which absorption thereon Face.Sample can be heated to the optional temperature of user with the heating mantle supplied.Digital temperature control and display installation On instrument front panel.After completing degasification, sample cell is transferred in analysis station.Quick coupling fittings are automatic during transfer Sealed sample pond, and then activation system to start to analyze.Dewar bottle (the dewar for being filled with coolant is increased manually Flask), submerge sample cell and cause to adsorb.Instrument is detected when (2 to 3 minutes) are completed in absorption, reduces Dewar automatically Bottle, and sample cell is slowly heated back to room temperature using in-building type hot air blower.Therefore, desorbed gases signal is shown in On digital table and surface area is directly presented in front panel display.Entire measurement (adsorption and desorption) circulation usually requires Less than six minutes.The technology measured using highly sensitive, thermal conductivity detectors when adsorption and desorption carry out adsorbate/ The concentration of inertia mediator admixture of gas changes.When being integrated by airborne electronic equipment and compared with calibration, detector provides suction The volume of attached or desorption gas.For absorption measure, using at 77K molecular cross sectional area be 0.162nm²N₂5.0 into Row calculates.Carry out a point analysis, and built-in microsever ensure BET surface area that is linear and calculating sample automatically (with m²/ g is unit).

According to one embodiment, the specific surface area of metallic can be at least about 0.1m²/ g, preferably at least about 0.2m²/ g.Meanwhile specific surface area is preferably no more than 10m²/ g and no more than about 5m²/g.In one embodiment, metal The specific surface area of particle is in about 0.7 and 1.7m²Between/g.

Organic vehicle

Conductive paste of the invention also includes organic vehicle.In one embodiment, organic with 100% total weight of cream Mediator is at least about 0.01wt%, preferably at least about 0.5wt%, more preferably at least about 1wt%, more preferably at least about 5wt%, more preferably at least about 10wt%, more preferably at least about 15wt%, more preferably at least about 20wt%, more preferably The amount of at least about 25wt% and more preferably at least about 30wt% are present in conductive paste.In a preferred embodiment, With 100% total weight of cream, conductive paste includes at least about 35wt% organic vehicle.In addition, with 100% total weight of cream, Conductive paste includes no more than about 60wt%, preferably no more than about 55wt%, preferably no more than about 50wt% and preferably No more than about 45wt%.In a preferred embodiment, with 100% total weight of cream, conductive paste includes no more than about 40wt%.

Preferred organic vehicle in the context of the invention is based on one or more solvents, preferably one or more are organic molten Solution, lotion or the dispersion liquid of agent, the form for ensuring the component of conductive paste to dissolve, emulsify or disperse exist.Preferably have Machine mediator is that those provide the optimal stability of conductive paste composition and assign the viscosity that the cream allows effective impressionability Organic vehicle.

In one embodiment, organic vehicle includes that organic solvent and optional adhesive (such as polymer), surface are lived One or more in property agent and thixotropic agent.For example, in one embodiment, organic vehicle include organic solvent in one or A variety of adhesives.

Preferred adhesive in the context of the invention be those contribute to form with favourable stability, impressionability, The adhesive of the conductive paste of viscosity and sintering property.Institute that is known and being deemed suitable for the context of the invention in fields There is adhesive to can be used as the adhesive in organic vehicle.Preferred adhesive (its classification for usually belonging to referred to as " resin ") It is polymer adhesive, monomeric cement and this adhesive combined as polymer with monomer.Polymer adhesive can be with It is the wherein copolymer containing at least two different monomers units in individual molecule.Preferred polymer adhesive is those poly- Close owner's chain in be loaded with functional group polymer adhesive, those be loaded with outside main chain functional group polymer adhesive and those The polymer adhesive of functional group is all loaded in main chain and outside main chain.The polymer of functional group is preferably loaded in main chain It is such as polyester, substituted polyester, polycarbonate, substituted polycarbonate, the polymerization for being loaded in main chain cyclic group Object, glycan, substituted glycan, polyurethanes, substituted polyurethanes, polyamide, substituted polyamide, The copolymerization of phenol resin, substituted phenol resin, the monomer of one or more in aforementioned polymer optionally with other comonomers Object or its at least two combination.According to one embodiment, adhesive can be polyvinyl butyral or polyethylene.It is preferred that The polymer that cyclic group is loaded in main chain be for example polyvinyl butyl compound (polyvinylbutylate, PVB) and Its derivative and or mixtures thereof poly- terpineol and its derivative.Preferred glycan is such as cellulose and its alkyl derivative, Preferably methylcellulose, ethyl cellulose, hydroxyethyl cellulose, propyl cellulose, hydroxypropyl cellulose, butyl cellulose With its derivative and its at least two mixture.Other preferred polymer are cellulose ester resin, such as acetate propionate fibre Dimension element, cellulose acetate-butyrate and any combination thereof.The polymer that functional group is preferably loaded with outside host polymer chain is those Be loaded with amide groups polymer, those be usually referred to as the polymer for being loaded with acid and/or ester group of acrylic resin or before being loaded with State the combined polymer or combinations thereof of functional group.The polymer that amide is preferably loaded with outside main chain is such as polyvinyl pyrrole Pyridine ketone (PVP) and its derivative.Preferably be loaded with outside main chain acid and/or ester group polymer be for example polyacrylic acid and its Derivative, polymethacrylates (PMA) and its derivative or polymethyl methacrylate (PMMA) and its derivative or it is mixed Close object.Preferred monomeric cement is or mixtures thereof monomer, terpin alcohol resin or rosin derivative based on ethylene glycol.It is preferred that The monomeric cement based on ethylene glycol be those with multiple ethers, multiple ester groups monomeric cement or those there is one The monomeric cement of ether and an ester group, preferred ether are methyl, ethyl, propyl, butyl, amyl, hexyl and high-carbon alkane Base ether, preferred ester group are acetic acid esters and its alkyl derivative, preferably or mixtures thereof ethylene glycol monobutyl ether monoacetate. The mixing of alkylcellulose (preferably ethyl cellulose), its derivative and itself and other adhesives in aforementioned adhesion agent list Object or it is other be most preferably adhesive in the context of the invention.With 100% total weight of organic vehicle, adhesive can be with The amount of at least about 0.1wt% and preferably at least about 0.5wt% exist.Meanwhile with 100% total weight of organic vehicle, Adhesive can be deposited with no more than about 10wt%, the preferably no more than amount of about 8wt% and no more than about 7wt% ?.

Preferred solvent is the component removed from cream with significance degree during baking.It is presented exhausted after firing At least about 80% is reduced preferably compared with before firing to weight, is reduced at least about preferably compared with before firing 95%.Preferred solvent is that those facilitate advantageous viscosity, impressionability, stability and the solvent for being sintered feature.Fields In all solvents that are known and being deemed suitable for the context of the invention can be used as the solvent in organic vehicle.Preferably Solvent be those standard ambient temperature and pressure (SATP) (298.15K, 25 DEG C, 77 ℉), 100kPa (14.504psi, Existing solvent, preferably those boiling points are greater than about 90 DEG C and greater than about -20 DEG C of fusing point in liquid form under 0.986atm) Solvent.Preferred solvent is polarity or nonpolar, proton or non-proton, aromatic series or non-aromatic.It is preferred molten Agent is single methanol, glycol, polyalcohol, monoesters, diester, polyester, monoether, diether, polyethers；In functional group comprising these classifications extremely It is few one or more, the solvent of the optionally functional group comprising other classifications, the functional group of other classifications is preferably ring-type Group, aromatic group, unsaturated bond, one or more O atoms are replaced into heteroatomic alcohol groups, the displacement of one or more O atoms Heteroatomic ester group is replaced into for heteroatomic ether group, one or more O atoms；With two kinds in aforementioned solvents or more than two The mixture of kind.Preferred ester in this context is the dialkyl ester of adipic acid, and preferred alkyl component is methyl, second The combination of base, propyl, butyl, amyl, hexyl and high-carbon alkyl or two kinds of difference described alkyl；Preferably adipic acid diformazan Ester；With two kinds or more than two kinds of adipate esters mixture.Preferred ether in this context is diether, preferably second two The dialkyl ether of alcohol, preferred alkyl component be methyl, ethyl, propyl, butyl, amyl, hexyl and high-carbon alkyl or two kinds not With the combination of the alkyl；With the mixture of two kinds of diether.Preferred alcohol in this context is level-one, second level and three-level Alcohol, preferably tertiary alcohol, preferably terpineol and its derivative or two kinds or mixture more than two kinds of alcohol.Preferably Combination is more than that a kind of solvent of different functional groups is the 2,2,4- trimethyl -1,3- pentanediol list isobutyric acid of commonly referred to as texanol Ester and its derivative；Commonly referred to as 2- (2- ethoxy ethoxy) ethyl alcohol of carbitol, alkyl derivative, preferably methyl, second Base, propyl, butyl, amyl and hexyl Carbitol, preferably hexyl Carbitol or butyl carbitol and its acetic ester derivative, Preferably acetate of butyl carbitol；Or aforementioned at least two mixture.It is organic with 100% total weight of organic vehicle Solvent can be deposited at least about 60wt% and the amount of more preferably at least about 70wt% and most preferably at least about 80wt% ?.Meanwhile with 100% total weight of organic vehicle, organic solvent can with no more than about 99wt%, no more than The amount of about 95wt% exists.

Organic vehicle can also include one or more surfactants and/or additive.Preferred surfactant is that The surfactant of the conductive paste with favourable stability, impressionability, viscosity and sintering property is contributed to form a bit.Affiliated neck All surface activating agent that is known and being deemed suitable for the context of the invention can be used as the table in organic vehicle in domain Face activating agent.Preferred surfactant is that those are based on straight chain, branched chain, aromatic series chain, fluorination chain, siloxane chain, polyethers The surfactant of chain and a combination thereof.Preferred surfactant is including but not limited to single-stranded, double-strand or multichain polymer.It is preferred that Surfactant can have nonionic, anion, cation, amphiphilic matchmaker property or amphoteric ion head.Preferred surface-active Agent can be or mixtures thereof polymer and monomer.Preferred surfactant can have pigment affinity groups, preferably Hydroxyl-functional with pigment affinity groups carboxylate (such as- 108, manufactured by BYK USA, Inc.), With pigment affinity groups acrylate copolymer (such as- 116, manufactured by BYK USA, Inc.), With pigment affinity groups modified polyether (such asDISPERS 655, by Evonik Tego Chemie GmbH Manufacture) and it is other with high pigment affinity group surfactant (such asDISPERS 662C, by Evonik Tego Chemie GmbH manufacture).Other preferred polymer not in list above include but is not limited to polyethylene glycol oxide, Or mixtures thereof polyethylene glycol and its derivative and alkyl carboxylic acid and its derivative or salt,.Preferably polyethyleneglycol derivative is Poly(ethylene glycol) acetic acid.Preferred alkyl carboxylic acid is that those alkyl carboxylic acids with fully saturated alkyl chain have list not with those Or mixtures thereof saturation or the alkyl carboxylic acid of how unsaturated alkyl chain.The preferred carboxylic acid with saturated alkyl chain is those alkyl Carboxylic acid of the chain length in about 8 to about 20 carbon atom ranges, preferably C₉H₁₉COOH (capric acid), C₁₁H₂₃COOH (lauric acid), C₁₃H₂₇COOH (myristic acid), C₁₅H₃₁COOH (palmitinic acid), C₁₇H₃₅COOH (stearic acid) or its salt or mixture.Preferred tool The carboxylic acid of unsaturated alkyl chain is C₁₈H₃₄O₂(oleic acid) and C₁₈H₃₂O₂(linolenic acid).Preferably monomcric surfactant is Benzotriazole and its derivative.If it is present with 100% total weight of organic vehicle, surfactant be can be at least About 0.01wt%.Meanwhile with 100% total weight of organic vehicle, surfactant is preferably no more than about 10wt%, excellent Selection of land no more than about 8wt% and no more than about 6wt%.

Preferred additive in organic vehicle is that those are different from aforementioned component and facilitate conductive paste favorable property Material, the favorable property for example advantageous viscosity, impressionability, stability and sintering feature.It can be used in fields Know and be deemed suitable for the additive of the context of the invention.Preferred additive includes but is not limited to thixotropic agent, viscosity tune Save agent, stabilizer, inorganic additive, thickener, emulsifier, dispersing agent and pH adjusting agent.Preferred thixotropic agent includes but unlimited In carboxylic acid derivates, preferably derivative of fatty acid, or combinations thereof.Preferably derivative of fatty acid includes but is not limited to C₉H₁₉COOH (capric acid), C₁₁H₂₃COOH (lauric acid), C₁₃H₂₇COOH (myristic acid), C₁₅H₃₁COOH (palmitinic acid), C₁₇H₃₅COOH (stearic acid), C₁₈H₃₄O₂(oleic acid), C₁₈H₃₂O₂(linolenic acid) and a combination thereof.Preferably include in this context The combination of fatty acid is castor oil.

Additive

Preferred additive is the component being added in cream in addition to other specifically mentioned components, is helped to improve The electric property of cream, the electrode of its manufacture or gained solar battery.In addition to being present in the additive in frit and mediator, Additive can also have an independent existence in conductive paste.Preferred additive includes but is not limited to thixotropic agent, viscosity modifier, emulsification Agent, stabilizer or pH adjusting agent, inorganic additive, thickener and dispersing agent or its at least two combination.It is preferred inorganic Organic metal additive include but is not limited to Mg, Ni, Te, W, Zn, Mg, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Rh, V, Y, Sb, P, Cu and Cr or its at least two combination, preferably Zn, Sb, Mn, Ni, W, Te, Rh, V, Y, Sb, P and Ru or its at least Two kinds of combination；Its oxide；The compound of those metal oxides can be generated after baking；Or in aforementioned metal at least Two kinds of mixture；At least two mixture in aforesaid oxides；Those metal oxides can be generated after baking At least two mixture in aforesaid compound；Or two kinds or more than two kinds any mixtures referred to above.? In one preferred embodiment, conductive paste includes the additive for promoting adhesion strength, such as Mn oxide (such as MnO₂), zinc oxide (such as ZnO), aluminum oxide (such as Al₂O₃) or bismuth oxide (such as Bi₂O₃)。

According to one embodiment, cream may include one or more additives of at least about 0.1wt%.Meanwhile with the 100% of cream Total weight, cream preferably include no more than about 10wt%, preferably no more than about 5wt% and most preferably no more than about One or more additives of 2wt%.In a most preferred embodiment, with 100% total weight of cream, conductive paste includes not surpass Cross one or more additives of about 1wt%.

Form conductive paste composition

In order to form conductive paste, using any method for being used to prepare composite cream known in fields by frit Material is combined with conductive metal particles and organic vehicle.Preparation method is not vital, as long as it generates homogenous disperse Cream.Component can be mixed such as with mixer, and the uniform cream of dispersion is made then across such as three-roll grinder.Except simultaneously will Other than all components mix, for example original glass material material and silver particles can be co-mulled and made into 2-24 hours in the ball mill To obtain the homogeneous mixture of frit and silver particles, then mixed with organic vehicle.

Solar battery

The invention further relates to solar batteries.In one embodiment, solar battery includes semiconductor substrate (such as silicon Chip) and any embodiment described herein conductive paste composition.

On the other hand, the present invention relates to pass through the solar battery including the following method preparation: will be described herein Any embodiment conductive paste composition be applied to semiconductor substrate (such as silicon wafer) and while roasting semiconductor substrate.

Silicon wafer

In other regions of solar battery, preferred chip of the invention have can expeditiously absorb light to produce Raw electron-hole pair and expeditiously crossing the boundary, the area that hole and electronics are preferably separated across p-n junction boundary Domain.Preferred chip of the invention is that those include the chip for the monolithic entity being made of preceding doped layer and back doped layer.

Chip preferably includes quadrivalent element, binary compound, ternary compound or the alloy by suitably adulterating.Herein Preferred quadrivalent element in context includes but is not limited to silicon, germanium or tin, preferably silicon.Preferred binary compound include but It is not limited to two kinds or the combination more than two kinds of quadrivalent elements, the binary compound of iii group element and group V element, group ii The binary compound of the binary compound or Group IV element and group vi element of element and group vi element.Preferred tetravalence member The combination of element includes but is not limited to the combination of two kinds or the element more than two kinds selected from silicon, germanium, tin or carbon, preferably SiC.It is preferred that Iii group element and the binary compound of group V element be GaAs.A preferred embodiment according to the present invention, chip It is silicon.Clearly refer to that the foregoing description of silicon is also applied for other wafer compositions described herein.

P-n junction boundary is located at the preceding doped layer of chip and the joint of back doped layer.In N-shaped solar battery, back Doped layer is doped with the n-type dopant for electron, and preceding doped layer is doped with the p-type doping for receiving electronics or supply hole Agent.In p-type solar battery, doped layer is doped with p-type dopant and preceding doped layer is doped with n-type dopant for back.According to A preferred embodiment of the invention, by providing the silicon substrate through overdoping first and then to one of the substrate Face applies the doped layer of opposite types to prepare the chip with p-n junction boundary.

Doped silicon substrate can by it is known in fields and be considered suitable for any method of the invention come Preparation.Preferred silicon substrate source of the invention includes but is not limited to monocrystalline silicon, polysilicon, amorphous silicon and the metalluragical silicon of upgrading, Most preferably monocrystalline silicon or polysilicon.Doping can be mixed with forming doped silicon substrate by adding during preparing silicon substrate Miscellaneous dose is come while being carried out or it can be carried out in the next steps.Doping after preparing silicon substrate can be for example, by gas Diffuser extension method carries out.Doped silicon substrate can also easily be bought.According to one embodiment, the initial dopant of silicon substrate It can be carried out simultaneously by adding dopant to silicon mixture come formed.According to another embodiment, preceding doped layer and height The application of the backing layer (if present) of doping can be carried out by vapour phase epitaxy method.This vapour phase epitaxy method is preferably at least about It is carried out at a temperature of 500 DEG C, preferably at least about 600 DEG C and most preferably at least about 650 DEG C.Meanwhile temperature is preferably not More than about 900 DEG C, preferably no more than about 800 DEG C and most preferably no more than about 750 DEG C.Vapour phase epitaxy method is preferably extremely It is carried out under the pressure of few about 2kPa, preferably at least about 10kPa and most preferably at least about 40kPa.Meanwhile pressure is preferably No more than about 100kPa, preferably no more than about 80kPa and most preferably no more than about 70kPa.

It is known that silicon substrate can show various shapes, surface texture and size in fields.It names just a few, substrate Shape may include cube, disk, chip and irregular polyhedrons.A preferred embodiment according to the present invention, chip It is that there are two the cubes of size and the third size significantly less than other two sizes similar, be advantageously equal for tool.Third Size can be at least 100 times smaller than the first two size.In addition, the silicon substrate with rough surface is preferred.A kind of evaluation lining The mode of bottom roughness be assess substrate subsurface surface roughness parameter, the subsurface compared to substrate total surface area compared with It is small, preferably less than about 1 the percent of total surface area, and its is substantially planar.Surface roughness parameter value passes through time table The ratio of the area of the area and theoretical surface in face provides, and the theoretical surface is by projecting to the subsurface by making Orientation move minimize and with formed on the flat surfaces of subsurface optimal fitting.The instruction of high surfaces roughness parameter value is thicker Rough, more irregular surface, and lower surface roughness parameter value indicates more smooth, flatter surface.According to the present invention, The surface roughness of silicon substrate is preferably modified so as in including but not limited to light absorption and to the multiple of the adhesion strength on surface Optimal balance is generated between factor.

Two larger sizes of silicon substrate be can change to adapt to needed for the application of gained solar battery.According to this hair Bright, the thickness of silicon wafer is preferably lower than about 0.5mm, more preferably below about 0.3mm and most preferably less than about 0.2mm. Some chips it is minimum with a thickness of 0.01mm or be greater than 0.01mm.

Preceding doped layer is preferably thinner than back doped layer.The thickness of preceding doped layer is further preferably at least about 0.1 μm and excellent No more than about 10 μm of selection of land, preferably no more than about 5 μm and most preferably no more than about 2 μm.

Dopant

Preferred dopant be those when being added in silicon wafer by by electronics or hole be introduced into band structure with Form the dopant on p-n junction boundary.Preferably, the attribute of these dopants and concentration are selected by specific optionally to adjust The band structure profile of humorous p-n junction and set light absorption and conductibility overview.Preferably p-type dopant includes but is not limited to Those add the dopant in hole into silicon wafer band structure.Known in fields and it is deemed suitable in the present invention All dopants hereafter can be used as p-type dopant.Preferred p-type dopant includes but is not limited to triad, especially For those of belonging to group 13 of periodic table triad.Preferred belonging to group 13 of periodic table element in this context includes but is not limited to Boron, aluminium, gallium, indium, thallium or its at least two combination, wherein boron is particularly preferred.

Preferred n-type dopant is the n-type dopant that those add electronics into silicon wafer band structure.Preferred N-shaped Dopant is the 15th race's element of periodic table.The 15th race's element of preferred periodic table in this context include but is not limited to nitrogen, Phosphorus, arsenic, antimony, bismuth or its at least two combination, wherein phosphorus is particularly preferred.

As described above, the various doping levels of p-n junction are variable to the required of tuning gained solar battery Property.Doping level is analyzed to measure using secondary ion mass spectrometry (SIMS).

According to some embodiments, semiconductor substrate (i.e. silicon wafer) shows greater than about 60 Ω/ electrical sheet resistance, is such as higher than About 65 Ω/, 70 Ω/, 90 Ω/ or 100 Ω/.In order to measure the electrical sheet resistance of the silicon wafer surface through overdoping, make With the device " GP4-Test Pro " (being obtained from GP Solar GmbH) equipped with package software " GP-4Test 1.6.6Pro ".For It measures, using 4 measuring principles.Two external probes apply constant current, and two internal probes measure voltage. Derive electrical sheet resistance using Ohm's law (Ohmic law) (as unit of Ω/).In order to measure average sheet resistance, to crystalline substance The point of 25 equal distributions of piece measures.In the air-conditioned room that temperature is 22 ± 1 DEG C, all set is balanced before measuring Standby and material.In order to measure, make " GP-Test.Pro " equipped with 4 measuring head (Part No.s with sharp tip 04.01.0018) to penetrate anti-reflecting layer and/or passivation layer.Apply the electric current of 10mA.Make measuring head and non-metallic chip Material, and start to measure.After the point of 25 equal distributions on measurement chip, calculated as unit of Ω/ flat Equal electrical sheet resistance.

Solar battery structure

At least one of realization above-mentioned purpose can be made by the solar battery obtained by method of the invention Contribution.Preferred solar battery of the invention is that those have in terms of the ratio that the gross energy of incident light is converted to power output There are efficient solar battery and those lightweights and durable solar battery.Under bottom line, solar battery packet It includes: doped layer, (iii) p-n junction boundary, (iv) back doped layer and (v) welding piece before (i) front electrode, (ii).Such as this paper institute It illustrates, solar battery can also include additional layer, special PERC solar battery.

Had and PERC solar-electricity of the invention according to the solar battery of double printing process preparations disclosed above The different structure in pond.

Anti-reflecting layer

It according to the present invention, can be using anti-reflecting layer as outer layer before electrode to be applied to three front of solar battery Apply.In one embodiment, anti-reflecting layer can also be similarly applied to the back surface of solar battery.Affiliated neck can be used All anti-reflecting layers that are known and being deemed suitable for the context of the invention in domain.Preferred anti-reflecting layer be those reduce by The anti-reflecting layer of the ratio of incident light of the ratio and increase for the incident light that front is reflected across front and to be absorbed by chip. Generate favorable for absorption/reflectivity, easily as conductive paste etching, in other ways to roasting conductive paste needed for temperature it is resistant simultaneously And it is preferred for not promoting the increased anti-reflecting layer of recombinant of the electronics and hole of neighbouring electrode interface.Preferred anti-reflecting layer Including but not limited to SiN_x、SiO₂、Al₂O₃、TiO₂Or its at least two mixture and/or its at least two layers combination.Root According to a preferred embodiment, anti-reflecting layer is SiN_x, specifically wherein use silicon wafer.

The thickness of anti-reflecting layer is adapted to the wavelength of appropriate light.A preferred embodiment according to the present invention, antireflection Layer with a thickness of at least 20nm, preferably at least 40nm and most preferably at least 60nm.Meanwhile thickness is preferably no more than about 300nm, no more than about 200nm and most preferably no more than about 90nm.

Passivation layer

One or more passivation layers can be applied on the front side and/or back side of silicon wafer as outer layer.It can be in front Apply one or more preceding passivation layers before electrode is formed or before applying anti-reflecting layer (if there is anti-reflecting layer).PERC is too Positive energy battery has the backside passivation layer that silicon wafer back side is applied to during manufacturing chip, such as via plasma-based vapor deposition skill Art.During manufacturing PERC solar battery, anti-reflecting layer before applying first then applies backside passivation layer, and finally apply Add back side cover cap rock.

Preferred passivation layer is the passivation layer that those reduce the rate of the electrons recombinant of neighbouring electrode interface.It can Using any passivation layer that is known in fields and being deemed suitable for the context of the invention.Of the invention is preferred blunt Changing layer includes but is not limited to aluminum oxide, silicon nitride, silica and titanium dioxide.For PERC solar battery, alumina Compound (such as Al₂O₃) be preferably used for forming backside passivation layer.The thickness of passivation layer is preferably at least 0.1nm, preferably extremely Few 10nm and most preferably at least 30nm.Meanwhile thickness is preferably no more than about 2 μm, preferably no more than about 1 μm and most Preferably no more than about 200nm.

Additional protective layer

In addition to above-mentioned layer, other layers can be added for mechanically and chemically protecting.Battery can be encapsulated to mention For chemoproection.According to a preferred embodiment, if such be encapsulated presence, using being often referred to as transparent thermoplastic resin Transparent polymer as encapsulation materials.Preferred transparent polymer in this context is silicon rubber and polyvinyl acetate second Enester (PVA).It can also be to addition transparent glass sheet before solar battery with to the mechanical protection provided above of battery.It can be with Back protection materials are added to the back side of solar battery to provide mechanical protection.Preferred back protection materials are those with good The back protection materials of good engineering properties and weatherability.Preferred back protection materials of the invention are poly- pairs with polyvinyl fluoride layer Polyethylene terephthalate.Both back protection materials are preferably in the lower section for being encapsulated layer (to be existed carrying on the back protective layer and being encapsulated In the case where).

Frame material can be added to obtain mechanical support to the outside of solar battery.Frame material is ripe in fields Know, and can be using any frame material for being deemed suitable for the context of the invention.Preferred frame material of the invention Material is aluminium.

The method for preparing solar battery

The solar battery of mackle brush

As set forth herein, the solar battery of mackle brush can be prepared by following: will be in such as (e.g.) main gate line First conductive paste of first limiting pattern of pattern is applied in the anti-reflection coating on silicon wafer frontside to form first layer. Then, the second conductive paste, the i.e. cream of invention disclosed herein can be applied at the top of first layer to form different pattern, If one layer thin grid line and/or another layer of main gate line are to reinforce the first pattern.Back side conductive paste is then applied to solar battery Back side is to form welding piece.Then aluminium cream is applied to substrate backside, the edge of the overlapping welding piece formed by back side conductive paste To form back surface field after baking.In this method, the first conductive paste composition is different from the second conductive paste composition.

The various methods of the first and second conductive paste of mackle brush are illustrated in Fig. 3 A-3D.For example, in figure 3 a, first In step, the first conductive paste is only used for printing main gate line, and in the second step, the second conductive paste (cream of the invention) is only used In the thin grid line of printing.In figure 3b, in the first step, the first conductive paste is only used for printing thin grid line, and in second step In, the second conductive paste (cream of the invention) is for printing thin grid line (top of the thin grid line of first layer) and main gate line.In fig. 3 c, The first step in first step is with Fig. 3 B is identical, but in the second step, and the second conductive paste is only used for printing main gate line.Most Afterwards, as illustrated in fig. 3d, the first conductive paste can be used for printing the thin grid line of first layer and main gate line, and the second conductive paste can To be only used for the printing thin grid line of the second layer.

Conductive paste can by it is known in fields and be deemed suitable for the context of the invention it is any in a manner of apply. Example include but is not limited to infiltrate, impregnate, toppling over, dripping, injecting, spraying, blade coating, curtain coating, brushing or printing or Its at least two combination.Preferred printing technology is ink jet printing, screen painting, mobile printing, lithographic printing, letterpress Or mould printing or its at least two combination.According to the present invention, conductive paste preferably passes through printing, preferably by halftone print Brush is to apply.Specifically, network optimization selection of land have diameter be about 40 μm or less than 40 μm (for example, about 35 μm or less than 35 μm, about 30 μm or less than 30 μm) mesh.Meanwhile network optimization selection of land has the mesh that diameter is at least 10 μm.

PERC solar battery

Following preparation PERC solar battery.Firstly, it is as explained above, front side diffusion layer is formed on a silicon substrate.? On on front side of substrate, then apply anti-reflection coating, such as those anti-reflection coating disclosed herein.Then, as passed through plasma-based gas Mutually the backside passivation layer of such as al oxide layer is applied on substrate back surface by deposition.It then can will be such as silicon nitride the cover layer Additional back layer be applied on the top of backside passivation layer.Then, partial rear passivation layer and additional back layer are removed with sudden and violent Reveal the region of underlying substrate.This step can be realized for example, by acid etching or laser drill.Then aluminium conductive paste is applied In on the top of back layer, therefore " hole " generated during being filled in removal process.In that region, when roasting aluminium cream Form local back surface field.Back side welding piece can be applied on back surface before or after applying aluminium cream.According to affiliated Known conventional method in field, front side electrode are also formed simultaneously with back side welding piece.

Exemplary PERC solar battery is illustrated in Fig. 2.In these schemas, term " AR " refers to anti-reflecting layer, art Language " BSF " refers to back surface field, term " AlO_x" refer to aluminum oxide backside passivation layer, term " SiN_x" refer to back side cover cap rock, Term " back side Al " refers to back aluminium cream, and term " back side Ag " refers to back side welding piece.

Heat treatment

Solar battery structure or PERC solar battery for mackle brush are subjected to substrate at one or more heat Manage step, such as (e.g.) conventional experience drying, infrared ray or ultraviolet curing and/or roasting.In one embodiment, substrate It can be roasted according to appropriate overview.Roasting sintering forms solid electrode by the conductive paste printed.Roasting is in fields It is well known, and can by be deemed suitable for the context of the invention it is any in a manner of realize.Roasting is preferably being higher than glass The T of glass material material_gLower progress.

According to the present invention, maximum temperature of the setting for roasting is below about 1,000 DEG C, is preferably lower than about 900 DEG C.It has adopted With temperature setting down to about 800 DEG C of boiler to be used to obtain solar battery.Roasting set temperature should also allow for metal Effective sintering of particle.Maturing temperature overview is normally set up to enable the organic material after-flame from conductive paste composition.Roasting Step is burnt to execute in air or under oxygen-containing atmosphere usually in belt boiler.Roasting preferably with quick method of roasting into Row, and total calcining time is at least 30 seconds and preferably at least 40 seconds.Meanwhile calcining time is preferably no more than about 3 points Clock, no more than about 2 minutes and most preferably no more than about 1 minute.Chip temperature is higher than 600 DEG C of time optimal Selection of land is within the scope of about 3 to 7 seconds.Substrate can achieve the peak temperature within the scope of about 700 to 975 DEG C for about 1 to 5 second Period.Roasting can also be carried out with the high transmission rates of for example, about 100-700cm/min, and the gained residence time is about 0.5 to 3 minute.Such as multiple humidity provinces in 3-12 area can be used for controlling required heat distribution.

The roasting of conductive paste on front and the back side can be executed simultaneously or sequentially.If being applied to the conductive paste in two faces With similar, preferably identical optimal roasting condition, then it is roasted to simultaneously appropriate.If appropriate, then roasting preferably same Shi Jinhang.In the case where sequentially being roasted, preferably applies and roast back conductive paste first, then apply conductive paste And it roasts to substrate.

Measure the property of conductive paste

Solar-electricity is measured using the commercial IV- tester " cetisPV-CTL1 " from Halm Elektronik GmbH The electric property in pond.During electrical measurement, all parts and solar battery to be tested of measuring device are held in 25 At DEG C.During actual measurement, this temperature should be measured on battery surface simultaneously by temperature probe.Xe arc lamp is with 1000W/ m²Known AM1.5 intensity daylight is simulated on battery surface.In order to make simulator reach this intensity, make lamp in a short period of time Quick flashing is by the degree of stability that " PVCTControl 4.313.0 " software of IV- tester is monitored until it reaches several times Only.Halm IV tester measures electric current (I) and voltage (V) using Multi-contact method to determine the IV curve of solar battery. In order to carry out this process, solar battery is placed between Multi-contact probe in a certain way so that needle probes with too Main gate line (i.e. track) contact of positive energy battery.The number of contact probe line is adjusted to the number of the main gate line on battery surface Mesh.All electrical values are directly measured automatically by the package software implemented according to this curve.Test is by same area ruler Very little, same wafer material forms and using the calibration solar battery from ISE Freiburg of identical front side Layout processing As reference standard, and by data compared with acceptance value.At least five chip processed in a manner of identical of measurement and Data are explained by calculating the average value of each value.Software PVCTControl 4.313.0 provides efficiency, fill factor, short circuit The value of electric current, series resistance and open-circuit voltage.For open-circuit voltage, the increase of 1-2mV is considered as significantly in the industry.

Solar cell module

Multiple solar batteries of the invention can be configured with space manner and be electrically connected to be formed and be referred to as mould The set of block configures.Preferred module of the invention can have various configurations, it is therefore preferable to which the rectangle for being referred to as solar panels is matched It sets.The mode and extremely a variety of mechanical arrangements of extremely a variety of electrical connection solar batteries and the fixed battery are to form set configuration Mode it is well-known in the art.Preferred method of the invention is that those generate low quality and power output ratio, low Volume and power output are than the method with high-durability.Aluminium is the preferred material for being mechanically fixed solar battery of the invention Material.

In one embodiment, it the series connection of multiple solar batteries and/or is connected in parallel and initially battery and most end battery Electrode tip be preferably connected to output connection.Battery contact is engaged into it to the region for having formed back side welding piece.Too Positive energy battery is typically encapsulated in as in the transparent thermoplastic resin of silicon rubber or ethylene vinyl acetate.Transparent glass sheet is placed In in the front surface for being encapsulated transparent thermoplastic resin.The back of the polyethylene terephthalate piece of pvf film will be for example coated with Protection materials, which are placed in, to be encapsulated below thermoplastic resin.These layered materials can heat in appropriate vacuum boiler to remove sky Gas, and a main body is then integrated by heating and compacting.Further, since the usually long-term outdoor placement of solar battery, Therefore it needs to cover solar battery periphery with the frame material being made of aluminium or its analog.

The present invention will now be described in conjunction with following non-limiting example.

Example 1- mackle brush solar battery structure

One group of exemplary frit compositions (G1-G4) respectively prepares according to such as the formula that is illustrated in the following table 1.Also make Standby two kinds refer to frit (G-REF1 and G-REF2).All amounts are all by the weight of 100% total weight of glass frit compositions Percents are measured to provide.Glass is formed using melting and process for quenching, to make starting material predetermined amounts in powder form Mixing.Mixture is heated in air or in oxygen-containing atmosphere then to form melt, then makes the melt quenching.It is then right It is quenched that glass is ground, ball milling and wire mark are to obtain the mixture with required granularity.

1. exemplary frit compositions G1-G4 of table and refer to glass

Then by each glass composition of about 4wt% and about 58wt% silver powder, about 37.5wt% organic vehicle peace treaty The combination of 0.5wt% oxide addition refers to cream (P- to form the such as exemplary cream P1-P4 illustrated in the following table 2 and two kinds REF1 and P-REF2).

The exemplary cream composite P1-P4 of table 2. and refer to cream

Subsequent compound is to realize uniform consistency.Mackle brush is applied, the net with 360 mesh stainless steel wiring is used By cream on front side of standard (by the expensive gold of he Li Shi of Pennsylvania cc Kang Shehuoken under about 16 μm of wiring diameters and 15 μm of EOM Belong to North America Kang Shehuoken Co., Ltd (Heraeus Precious Metals North America Conshohocken LLC, West Conshohocken, Pennsylvania) manufacture SOL9621H) screen painting arrives has 90 Ω/ thin slice electric To form thin grid line on front side of the blank polycrystalline silicon wafer of resistance.Then as illustrated in Figure 4, cream and exemplary cream halftone will be referred to It is printed on above thin grid line to form main gate line.Using commercially available back side cream to form the overall length and width that extend across battery The back side welding piece that degree is about 4mm.Then, by commercially available aluminium back side cream be printed on whole remaining areas of battery back side with Form aluminum back surface field.Subsequent dry cell at moderate temperatures.Then roasting under about 700-975 DEG C of peak temperature has The silicon substrate of front and back sides cream by printing.

Then according to parameter measurement cream P1-P4 described in this paper and with reference to cream electric conductivity and be set forth in the following table 3 In.Relative to reference cream P-REF1, by the data of each exemplary cream relative to 100 standardization.As can be seen, exemplary cream P1 Show higher open-circuit voltage compared with reference cream P-REF1 with P2, shows that exemplary cream causes more the bottom surface layer of substrate Thus low damage reduces silicon substrate and shunts.Compared to reference cream P-REF2, (it does not have MoO₃) contain increasingly higher amount MoO₃Exemplary cream P3 mixing paste P4 also show increased open-circuit voltage (Voc) compared to P-REF2.

The electric property of 3. cream P1-P4 of table

Example 2-PERC solar cell application

The same example cream of subsequent example 1 and reference cream (in addition to P3) are used to form PERC solar wafer (by Russia Strangle ridge state Hillsborough u s company, the solar energy world (SolarWorld Americas Inc., Hillsboro, Oregon) manufacture) on back side welding piece.

It in this example, will mark under about 35 μm of wiring diameters and 5 μm of EOM using the net with 280 mesh stainless steel wiring Quasi- front side cream is (by the he Li Shi noble metal North America Kang Shehuoken Co., Ltd of Pennsylvania cc Kang Shehuoken (Heraeus Precious Metals North America Conshohocken LLC,West Conshohocken, Pennsylvania) the SOL9620A manufactured) screen painting to PERC solar cell wafer (is purchased from Oregon Xi Ersi The u s company, the solar energy world (SolarWorld Americas Inc., Hillsboro, Oregon) of Greensboro) front side on Form thin grid line and main gate line.PERC solar cell wafer has had the open passivating back in the part for being applied to its back side Layer.As for the situation, it is printed on back surface by the exemplary cream of example 1 and with reference to cream to be formed and extend across battery overall length And the back side welding piece that width is about 3.5mm and length is 1.53mm.Then, by commercially available aluminium back side cream (by China Guangdong Guangzhou Ruxing Technology Development Co., Ltd (Guangzhou Ruxing Technology Development Co., Ltd., Guangdong, China) manufacture RUX28K30) be printed on above wafer backside it is spacious with the part of overleaf passivation layer Aluminum back surface field is formed in the region opened and slightly overlaps back side welding piece.Subsequent dry cell at moderate temperatures.It connects Under about 700-975 DEG C of peak temperature roasting have by printing front and back sides cream silicon substrate.

It is secondary in two batches that exemplary cream is applied on PERC solar battery back side, and cream P1 and P2 are the one of batch 1 Part and cream P3 and P4 are a part of batch 2.

Then according to the electric conductivity of parameter measurement cream described in this paper and it is set forth in the following table 4 and 5.Relative to ginseng Cream P-REF1 is examined, by the data of P1 and P2 relative to 100 standardization, and relative to reference cream P-REF2, by P3 and P4 Data relative to 100 standardization.As can be seen, each exemplary cream is corresponding compared to its to show higher open circuit electricity with reference to cream Pressure, shows that exemplary cream causes lower damage to the backside passivation layer of PERC solar battery.Contain relatively higher amount MoO₃Relatively lower amount of Bi₂O₃The cream P2 of (compared to other examples glass) shows highest Voc.

The electric property of 4. cream P1 and P2- batch 1 of table

	P-REF	P1	P2
				Voc, V	100	1.002021	1.002642

The electric property of 5. cream P3 and P4- batch 2 of table

	P-REF2	P3	P4
				Voc, V	100	1.0019	1.0002

These advantages of the invention and further advantage will be shown for those skilled in the art by aforementioned specification And it is clear to.It therefore, those skilled in the art will realize that can be without departing substantially from extensive concept of the invention of the invention the case where Under above-described embodiment made be altered or modified.The specific size of any specific embodiment describes for illustration purposes only. It is therefore to be understood that the present invention is not limited to specific examples described herein, but it is intended in the scope of the present invention With all changes and modification in spirit.

Claims

1. a kind of conductive paste composition, it includes:

Metallic；

At least one frit；With

Organic vehicle,

Wherein at least one frit be free from lead and include:

(i)SiO₂、B₂O₃And Bi₂O₃, wherein with 100% total weight of at least one frit, SiO₂、B₂O₃And Bi₂O₃ Total content be at least about 65-95wt%；

(ii) at least one basic anhydride of about 5-20wt%；With

(iii) MoO of about 3-10wt%₃。

2. conductive paste composition according to claim 1, wherein at least one basic anhydride include sodium oxide molybdena (Na₂) and lithia (Li O₂O)。

3. conductive paste composition according to any one of the preceding claims, wherein at least one frit It further includes in niobium oxide, aluminum oxide, oxysulfide, seleno oxide, tellurium oxide, barium oxide and tungsten oxide It is at least one.

4. conductive paste composition according to claim 3, wherein the frit further includes Nb₂O₅。

5. conductive paste composition according to any one of the preceding claims, wherein (SiO₂+B₂O₃+Bi₂O₃) with (MoO₃+Nb₂O₅) weight ratio be 8-25.

6. conductive paste composition according to any one of the preceding claims, wherein at least one frit It further comprise ZnO.

7. conductive paste composition according to any one of the preceding claims, wherein ((SiO₂+B₂O₃+Bi₂O₃)+ (MoO₃+Nb₂O₅)) it with the weight ratio of (basic anhydride+ZnO) is 4-18.

8. conductive paste composition according to any one of the preceding claims, wherein at least one frit Glass softening point be 400-550 DEG C.

9. conductive paste composition according to any one of the preceding claims, wherein at least one frit Glass softening point be 650-800 DEG C.

10. conductive paste composition according to any one of the preceding claims, wherein with conductive paste combination 100% total weight of object, the conductive paste composition include at least about 30wt% and no more than about 99wt% metallic.

11. conductive paste composition according to any one of the preceding claims, wherein the metallic includes Silver.

12. conductive paste composition according to any one of the preceding claims, wherein the conductive paste composition At least one frit comprising at least about 0.5wt% and no more than about 10wt%.

13. conductive paste composition according to any one of the preceding claims, wherein the conductive paste composition It further includes containing MnO₂Adhesion promote additive.

14. a kind of method for preparing passivation emitter-base bandgap grading back side solar battery, it includes following steps:

Back side conductive paste is applied thereto on the back side for being formed with the silicon substrate of at least one backside passivation layer, the back side is blunt Change and is formed with multiple openings in layer with the region of the exposure silicon substrate；

Apply aluminium conductive paste in the opening of the backside passivation layer to contact the silicon substrate；With

The silicon substrate is heated,

Wherein the back side conductive paste includes:

Metallic；

At least one frit；With

Organic vehicle,

Wherein at least one frit be free from lead and include:

(ii) at least one basic anhydride of about 5-20wt%；With

(iii) MoO of about 3-10wt%₃。

15. according to the method for claim 14, it is further contained in front of the step for heating the silicon substrate, Before being formed in the front surface of the silicon substrate the step of gate electrode.

16. a kind of passivation emitter-base bandgap grading back side solar battery, it includes:

Silicon substrate with front surface and back surface；

Backside passivation layer on the back surface of the silicon substrate is formed with multiple openings in the backside passivation layer；

It is formed in the aluminium back contact in the opening of the backside passivation layer；

At least one back side welding piece on the back surface of the silicon substrate, the back side welding piece according to right by wanting Conductive paste composition described in asking 1 is formed；With

The preceding gate electrode being formed in the front surface of the silicon substrate.

17. a kind of method for forming solar battery, it includes following steps:

First conductive paste is printed onto silicon substrate front surface to form first group of electrode；

Second conductive paste is printed on the top of first conductive paste to form second group of electrode；And

The silicon substrate is heated,

Wherein first conductive paste is different from second conductive paste, and second conductive paste includes:

Metallic；

At least one frit；With

Organic vehicle,

Wherein at least one frit be free from lead and include:

(ii) at least one basic anhydride of about 5-20wt%；With

(iii) MoO of about 3-10wt%₃。

18. according to the method for claim 17, wherein first group of electrode is main gate line.

19. according to the method for claim 17, wherein second group of electrode is thin grid line.

20. a kind of solar battery, it includes:

Silicon substrate, surface are applied with anti-reflection coating；

First group of electrode being formed directly into the anti-reflection coating；With

Second group of electrode being formed on the top of first group of electrode, wherein second group of electrode is by according to claim Conductive paste composition described in 1 is formed.