CN103515459A

CN103515459A - Paste composition for solar battery electrode

Info

Publication number: CN103515459A
Application number: CN201310259487.0A
Authority: CN
Inventors: 吉野泰; 角田航介
Original assignee: Noritake Co Ltd
Current assignee: Noritake Co Ltd
Priority date: 2012-06-26
Filing date: 2013-06-26
Publication date: 2014-01-15
Also published as: TW201403627A; JP2014007347A; JP5937904B2

Abstract

Provided is a paste composition for a solar battery electrode, and the paste composition is suitable for a solar battery of a shallow junction emitting electrode structure, and can enable an FF value and a current value to be increased and improve the conversion efficiency by reducing contact resistance and inhibiting recombination of generated electrons. Since a light receiving surface electrode is made of thick film silver, in a firing-through process, the dissolution amount of Ag in glass becomes sufficient and a Ag crystal nucleus is moderately generated, thus the series resistance is low and recombination of generated electrons is difficult to occur, thus, the FF value and the current value become large, high conversion efficiency can be obtained, the thick film silver contains lead glass in a range of 1 to 10 parts by weight relative to 100 parts of silver by weight, the lead glass contains SnO with a proportion in a range of 0.5 to 20 mol% while containing Li or contains SnO with a proportion in a range of 0.5 to 12 mol% without containing Li.

Description

Electrode of solar battery paste composite

Technical field

The present invention relates to utilize the conductive paste composition that electrode of solar battery is used that is suitable for that burns till the formation of perforation (fire through) method.

Background technology

For example, general silicon is that solar cell has following structure: at the upper surface of the silicon substrate as p-type poly semiconductor across n ⁺layer there is antireflection film and sensitive surface electrode, and at lower surface across p ⁺layer have backplate (following, when not distinguishing them referred to as " electrode ".), by electrode, take out the electric power producing at semi-conductive pn knot by being subject to light.Above-mentioned antireflection film is for keeping sufficient visible light transmissivity and reducing surface reflectivity and improve the film that is subject to optical efficiency, the film of silicon nitride, titanium dioxide, silicon dioxide etc., consists of.

Because the resistance value of above-mentioned antireflection film is high, so hinder the efficient electric power producing at semi-conductive pn knot that takes out.Therefore, the sensitive surface electrode of solar cell for example utilizes and is called as the method formation of burning till perforation.In this electrode forming method, for example, above-mentioned antireflection film is being arranged on to n ⁺after on whole on layer, utilize for example silk screen print method with suitable shape coating electrically conductive, to stick with paste on this antireflection film, and implement to burn till processing.Above-mentioned conductive paste is for example to take the paste that silver powder, frit (pulverizing as required the laminar or pulverous glass fragment forming in molten raw and after carrying out chilling), organic vehicle, organic solvent be principal component, in sintering process, glass ingredient in this conductive paste can destroy antireflection film, so by conductor composition and n in conductive paste ⁺layer forms ohmic contact (for example,, with reference to patent documentation 1.）。By coordinating the various micro constitutents that formed by the metals such as phosphorus, vanadium, bismuth, tungsten or compound etc. to obtain conduction in this conductive paste.According to above-mentioned electrode forming method, and partially to remove antireflection film and compare in the situation that this remove portion forms electrode, operation becomes simply, also can not produce remove portion and electrode and form the problem that the position of position is offset.

In the sensitive surface electrode of such solar cell forms, in order improving, to burn till connectivity, to improve ohmic contact, and then improve Fill factor (FF value), effciency of energy transfer etc., various schemes have just been proposed from the past.For example, by add phosphorus, Fan,Bi Deng 5 family's elements in conductive paste, promote the redox to glass and silver-colored antireflection film, improved and burnt till connectivity (for example,, with reference to above-mentioned patent documentation 1.）。In addition, by add chloride, bromide or fluoride in conductive paste, these additive auxiliary glasses and silver destroy antireflection film be used for improve ohmic contact (for example,, with reference to patent documentation 2.）。As above-mentioned fluoride, show lithium fluoride, nickel fluoride, aluminum fluoride.In addition, also show and except above-mentioned each additive, also add 5 family's elements.In addition, above-mentioned glass is for example pyrex.

In addition, the paste that patent documentation 3 is recorded, is when mixing organic bond, solvent, electroconductive particle, frit are modulated paste, by adding tin compound, to seek to improve the paste of FF value.According to this, stick with paste, the contact resistance step-down of the electrode of formation, has obtained excellent FF value.

In addition, once proposed in the paste of the argentiferous of the glass of the silver that contains 85～99 % by weight and 1～15 % by weight, making this glass is the PbO that contains 15～75 % by mole and the SiO of 5～50 % by mole ₂, and containing B ₂o ₃composition (for example,, with reference to patent documentation 4.）。The paste of this argentiferous is for the paste of the electrode formation of solar cell, by using the glass of above-mentioned composition, can improve ohmic contact.In above-mentioned glass, can contain the P of 0.1～8.0 % by mole ₂o ₅, or the Sb of 0.1～10.0 % by mole ₂o ₅, and then, can contain the alkali metal oxide (Na of 0.1～15.0 % by mole ₂o, K ₂o, Li ₂o).

In addition, the application's applicant had previously proposed frit by the PbO that contains 46～57 % by mole, the B of 1～7 % by mole ₂o ₃, the SiO in the scope of 38～53 % by mole ₂the paste composite for electrode of solar battery that forms of glass (for example, with reference to patent documentation 5.）。This paste composite is by expanding optimum burning temperature-forming scope in the firing process of solar cell, improves the average output power of every manufacture batch.

In addition, the application's applicant had once proposed frit by containing Li ₂o is that 0.6～18 % by mole, PbO are 20～65 % by mole, B ₂o ₃be 1～18 % by mole, SiO ₂be that the paste composite for electrode of solar battery that forms of the glass in the scope of 20～65 % by mole is (for example, with reference to patent documentation 6.）。Due to according to this paste composite, can obtain the excellent connectivity of burning till, so can not make ohmic contact, line resistance worsen by sensitive surface electrode graph thinning, therefore, the solar battery cell battery that light-to-current inversion efficiency is high can be accessed, and the shallow emitter of high film resistor can be performed well in.The above-mentioned glass more amount that contains compared with the past is as alms giver's Li, although Li is avoided conventionally in semiconductor applications, in solar cell purposes, appropriateness is containing sometimes obtaining good connectivity and the aggressivity of burning till.

Technical literature formerly

Patent documentation 1: Japanese kokai publication sho 62-049676 communique

Patent documentation 2: Japanese kokai publication hei 11-213754 communique

Patent documentation 3: TOHKEMY 2008-010527 communique

Patent documentation 4: Japanese Unexamined Patent Application Publication 2008-520094 communique

Patent documentation 5: TOHKEMY 2010-199334 communique

Patent documentation 6: TOHKEMY 2011-066354 communique

Summary of the invention

Yet, in above-mentioned solar cell, once proposed n layer attenuation by making to be positioned at sensitive surface side reduce surperficial recombination velocity, to take out the shallow emitter of more electric current.When carrying out shallow emitter, particularly near short wavelength side 400nm also contributes to generating, so think to be desirable answer aspect the efficiency of raising solar cell.But on the contrary, there is following inconvenience: need to make element cell is high film resistor; For example, due to the donor element (phosphorus) of near surface, so the potential barrier that concentration declines between Ag-Si increases, be difficult to guarantee the ohmic contact of sensitive surface electrode; So fully destroy antireflection film and electrode do not invade pn and tie such depth of invasion and control very difficult in burning till perforation because pn knot shoals; Etc..

In addition, the n layer thickness of silicon solar cell element cell is in the past 100～200nm, and the n layer thickness of shallow emitter is 70～100nm.By attenuation in this wise, can reduce by being subject among electricity that light produces, arrive the part that becomes heat before pn knot and cannot effectively utilize, therefore, short circuit current increases, and then has improved generating efficiency.

The paste composite that above-mentioned patent documentation 1,2,4,5 is recorded, is to improve the paste composite of the characteristic of the solar cell of structure in the past, but still not talkative abundant.And, the problem that existence cannot be corresponding with the high film resistor element cell using in shallow emitter, cannot obtain good ohmic contact.

To this, the paste composite according to recording in above-mentioned patent documentation 6, can further improve ohmic contact, also can be applicable to as described above shallow emitter.Yet, in this paste composite, be difficult to suitably control together and burn till connectivity and intrusion amount, be difficult to especially not invade the so shallow pn knot of shallow emitter.In addition, in the high film resistor element cell of using at shallow emitter, although donor concentration is also not enough, also there is the problem of deficiency on alms giver's compensation effect of Li only.That is, be difficult to fully improve FF value and conversion efficiency.

In addition, in above-mentioned patent documentation 3, although show by being made as the paste that contains Sn compound, form, contact resistance is declined, and then raising FF value, but the inventor etc. carry out the result of supplementary test, although can confirm that by adding Sn compound some improve effect is to be limited to the still result of inadequate characteristic.The results presumption that the inventor etc. further study repeatedly goes out, and the effect that the interpolation of above-mentioned Sn compound brings is that Sn enters in the structure of glass, thus, improved the solubility of Ag to glass, it is large that the Ag nucleus producing by recrystallization becomes, and then contact resistance is reduced.Think when in glass, contain cationic outer-shell electron number be 18 or have 18+2 such play element that polarizability is strong, such as Sn, Zn, In, Pb, Sb, Bi, Fe, Cd, Te ion etc., alkali metal ion time, produce powerful residue adhesion, strengthened the molecular separating force between other metals and glass, the Ag meltage in glass increases.

Fig. 1 (a) and (b) are for thereby the schematic diagram because of the effect of above-mentioned Ag nucleus characteristic variations is described.By above-mentioned burning till, connecting during the sensitive surface electrode carrying out forms, interface formation at silicon substrate 50 and sensitive surface electrode 52 in sintering process has glassy layer 54, at this glassy layer 54 and silicon substrate 50 interface, the Ag being at high temperature added in glass separates out and carries out recrystallization when cooling.Because recrystallization Ag has high conductivity, thus the conductive path from silicon substrate 50 to sensitive surface electrode 52 become, but this conductive path changes according to the generation state of this recrystallization Ag.

Fig. 1 (a) is the situation that generates larger recrystallization Ag56.When using glass that the solubility of Ag is large when (containing the glass that has added Te etc.), it is large that recrystallization Ag56 becomes, and quantity reduces, and the number that is present in glass-Si near interface tails off.In this structure, as shown in the figure, the electronics of generation is by silicon substrate 50(n ⁺layer), in and in recrystallization Ag56, via the silver particles 58 contacting with it, move to sensitive surface electrode 52.Therefore, although so due to by declining as low-resistance recrystallization Ag56 inside series resistance Rs, so because the quantity of recrystallization Ag56 is few by the fast n of recombination velocity ⁺distance in layer is elongated, and therefore, electric current reduces, conversion efficiency step-down.Although think that the interpolation of Sn compound of above-mentioned patent documentation 3 declines contact resistance Rc by such effect, improve FF value, realized thus improved efficiency, cannot obtain as described above playing the supplementary test result of abundant effect.

On the other hand, Fig. 1 (b) generates a plurality of smaller, situations of nano level recrystallization Ag60 for example.For example, by using the little glass (glass that does not contain or contain less Li) of solubility of Ag, recrystallization Ag60 diminishes and quantity increases, so be present in the number of silicon substrate 50-glassy layer 54 near interfaces, becomes many.In this structure, as shown in the figure, when the electronics producing reaches the recrystallization Ag60 at interface, although a part is directly conducted to silver particles 58, but plurality is with Ag-glass-Ag-... such jump conduction is main by arriving sensitive surface electrode 52 in the high glass of resistance value, so series resistance Rs uprises.Therefore, although a part of electronics becomes heat and loses in the high glass of resistance, because recombination velocity is slow, thus current value uprise, but because resistance is high, so FF value step-down.In addition, the glass that Ag solubility is little, when having suitable composition, separates out Ag nucleus in glassy layer 54 integral body, then due to crystalline growth more reposefully, so can obtain the structure shown in above-mentioned Fig. 1 (b).Yet at many compositions of, Si few such as alkali and/or Pb etc., reduces by temperature during glass that the solubility of Ag sharply declines forms, because of the variation that Si amount and/or Ag measure, Ag solubility, erosive velocity easily change.When solubility significantly reduces, at glassy layer 54 and the near interface of silicon substrate 50 and sensitive surface electrode 52, generate nucleus, crystalline growth also becomes sharply, it is very big that recrystallization Ag also becomes, therefore, there is leakage current in the damage of the pn of silicon substrate near surface knot, and then output characteristic reduces.That is the tendency that the glass that, Ag solubility is little is narrowed down by the optimum range forming.In addition, even if also there is fine recrystallization Ag60 above-mentioned Fig. 1 (a) in the situation that, but compare seldom with the situation of Fig. 1 (b), useless in the explanation of the bang path of electronics, so omission.

The invention that above-mentioned situation completes as background is take in the present invention, its object is, a kind of electrode of solar battery paste composite is provided, it is suitable for forming, being particularly suitable for by burning till the sensitive surface electrode of the solar cell that perforation method carries out the solar cell of the shallow emitter structure that n layer is thin, by making the combination again of the electronics of contact resistance decline and inhibition generation, can make FF value and the current value of solar battery cell battery increase, and then improve conversion efficiency.

In order to realize such object, as purport of the present invention, be a kind of electrode of solar battery paste composite, it contains electroconductive powder, frit and vehicle, and above-mentioned frit contains lead glass, and above-mentioned lead glass contains the Sn that is scaled the scope of 0.5～20.0 % by mole by oxide.

If so, owing to using in paste composite at electrode of solar battery, frit contains lead glass, above-mentioned lead glass contains Sn with the scope of 0.5～20.0 % by mole, so when using above-mentioned electrode of solar battery to form sensitive surface electrode with paste composite by burning till perforation method on silicon substrate, Ag meltage in glass increases, and appropriateness produces Ag nucleus.That is, can become the suitable state between the state shown in above-mentioned Fig. 1 (a) and (b).Therefore, because electronics moves with the conduction of jumping in the glassy layer being formed between silicon substrate and sensitive surface electrode, and the movement of electronics from glassy layer to sensitive surface electrode, directly the ratio of conduction becomes many, so the abundant step-down of series resistance and again combination are also difficult to occur, therefore FF value and current value are large, and then obtain the solar battery cell battery that conversion efficiency is high.The amount of above-mentioned Sn need to be more than 0.5 % by mole, and when lower than 0.5 % by mole, Ag meltage is very few, and then the size of recrystallization Ag becomes too small, and therefore, series resistance uprises, and Fill factor diminishes.In addition, when surpassing 20.0 % by mole, Ag meltage becomes excessive, and then the size of recrystallization Ag becomes excessive, therefore, combination more easily occurs, thereby conversion efficiency is reduced.

And, according to the present invention, owing to containing the frit of Sn by use, Ag meltage is increased, so also there is the advantage of easy control erosion amount.By the way, though make Pb, Sb, Bi, Te amount fully many, make alkali number fully many etc., also can make Ag meltage increase, but exist the change, the particularly change of Pb/Si ratio that form to have influence on the problem of erosion amount control.In addition, owing to increasing alkali number and reduce viscosity, erosive velocity is accelerated, so the problem that exists suitable firing range to narrow down.

In addition, although lysed Ag ₂o and Na ₂o etc. similarly exist as netted modification oxide (Si-O-Ag) in glass structure, but when implementing to process for burning till of electrode formation, by polyad valency ion, Ag ion is by thermal reduction, cause the generation of Ag nucleus and the growth of Ag crystallization, thereby recrystallization Ag is separated out.The behavior of separating out of recrystallization Ag, same with general karyogenesis and growth theory, be subject to the impact of Ag meltage, firing temperature, time, cooling rate.

By the way, the paste of recording in above-mentioned patent documentation 3 is used not containing the glass of Sn, adds Sn compound, but be estimated as described above when modulation is stuck with paste, by Sn contained in this paste, enter into glass structure, thereby Ag ion is separated out recrystallization Ag by thermal reduction as described above.Therefore, owing to entering into the Sn of glass structure in such structure, be limited to amount seldom, so cannot obtain sufficient additive effect, by the glass being made as containing Sn, form as the present invention, can suitably control separating out of recrystallization Ag.

In addition, above-mentioned frit can be a kind of lead glass, but can be to be also mixed with the softening point frit of different glass of more than two kinds mutually.The glass mixing can be all lead glass, except above-mentioned, containing the lead glass of Sn, also can be made as crown glass.

In addition, paste composite of the present invention, has stable Ohmic resistance, even if also have advantages of not only with respect to the substrate of low film resistor, with respect to the high film resistor substrate of 80～120 Ω/ left and right, also can access fully low contact resistance.Therefore, by control, be that electrode does not invade pn and ties, thereby obtain leakage current low, be the solar battery cell battery that parallel resistance is high, Fill factor is large, current value is large and light-to-current inversion rate is high.

At this, preferably: above-mentioned lead glass is that the scope with 0.5～20.0 % by mole contains Sn, contains Li with the scope of 0.6～18 % by mole by oxide conversion ₂o, with the scopes of 24～64 % by mole, contain PbO, with the scope of 1～18 % by mole, contain B ₂o ₃, with the scope of 11～40 % by mole, contain SiO ₂, with the scope of 0～6.0 % by mole, contain P ₂o ₅lead glass.Thus, in containing the composition of Li, because becoming component, each is defined in more suitable scope, so can obtain FF value more greatly and the higher solar battery cell battery of conversion efficiency Eff.

In addition, preferred: above-mentioned lead glass is that the scope with 0.5～12.0 % by mole contains Sn, with the scopes of 55～65 % by mole, contains PbO, with the scope of 1～8 % by mole, contains B by oxide conversion ₂o ₃, with the scope of 21～36 % by mole, contain SiO ₂, with the scope of 0～4.0 % by mole, contain P ₂o ₅, and containing Li ₂the lead glass of O.Thus, not containing in the composition of Li, because each becomes, component is standby to be determined in more suitable scope, so can obtain the larger and higher solar battery cell battery of conversion efficiency Eff of Fill factor FF.

In addition, in the composition of above-mentioned each lead glass, PbO is the composition that makes the softening point decline of glass, it is the composition that can realize easy fired, in order to obtain the good connectivity of burning till, respectively preferably: in containing the composition of Li, PbO is more than 24 % by mole and below 64 % by mole, containing PbO in the composition of Li, be not more than 55 % by mole and below 65 % by mole.In any composition system, all there is the tendency that softening point becomes too high when PbO measures lower than lower limit, become and be difficult to vitrifying and be difficult to antireflection film erosion, and then become and be difficult to obtain good ohmic contact.On the other hand, exist when surpassing higher limit, the tendency that softening point becomes too low, aggressivity is excessively strong, destroys pn and ties, and then easily produce the problem that FF value diminishes etc.The PbO amount scope of 30～61 % by mole more preferably in containing the composition of Li, is particularly preferably the scope of 35～60 % by mole.In addition,, containing the scope of 55～62 % by mole more preferably in the composition of Li, be not particularly preferably the scope of 58～62 % by mole.

In addition, B ₂o ₃being the oxide (forming the composition of the skeleton of glass) that forms glass, is the composition for reducing the softening point of glass, in order to obtain the good connectivity of burning till, respectively preferably: B in containing the composition of Li ₂o ₃more than being 1 % by mole and below 18 % by mole, B in not containing the composition of Li ₂o ₃more than being 1 % by mole and below 8 % by mole.In any composition system, exist and work as B ₂o ₃amount is during lower than lower limit, and the tendency that the viscosity of glass uprises, becomes and be difficult to corrode to antireflection film, and then becomes and be difficult to obtain good ohmic contact and moisture-proof also easily declines.In addition, work as B ₂o ₃measure when very few, easily produce the tendency that Voc declines and leakage current increases.On the other hand, even if surpass higher limit, easily produce on the contrary that Voc declines and leakage current increases, and then the too low tendency of the viscosity of glass, so easily produce that aggressivity is excessively strong, pn ties destroyed etc. problem.B ₂o ₃amount, the scope of 2.8～12 % by mole more preferably in containing the composition of Li, is more preferably the scope of 4～8 % by mole.

In addition, SiO ₂being the oxide that forms glass, is for improving the chemical-resistant composition of glass, in order to obtain the good connectivity of burning till, respectively preferably: SiO in containing the composition of Li ₂more than being 11 % by mole and below 40 % by mole, SiO in not containing the composition of Li ₂more than being 21 % by mole and below 36 % by mole.In any composition system, work as SiO ₂amount is during lower than lower limit, and chemical resistance is not enough, and easily becomes and be difficult to form glass.On the other hand, while surpassing higher limit, softening point is too high and be difficult to vitrifying, thereby is difficult to antireflection film corrode, and then easily becomes and can not obtain good ohmic contact.SiO ₂amount, containing the scope of 20～36 % by mole more preferably in Li system, is particularly preferably the scope of 24～32 % by mole.In addition, not containing the scope of 25～29 % by mole more preferably in Li system, be particularly preferably the scope of 27～29 % by mole.

In addition, not only preferably PbO and SiO ₂respectively in above-mentioned scope, and then respectively preferably: Pb/Si(mol ratio) in containing Li system be more than 0.6 and 5.0 below, be more than 1.5 and below 2.9 not containing Li in being.In any composition system, when Pb/Si mol ratio is during lower than lower limit, burn till connectivity and reduce, the contact resistance of sensitive surface electrode and n layer easily uprises.On the other hand, when Pb/Si mol ratio surpasses higher limit, it is large that leakage current easily significantly becomes, so FF value all declines in any case, easily becomes and can not obtain sufficient output characteristic.Pb/Si(mol ratio) containing more preferably 1～2.5 scope, more preferably 1.19～2.13 scope in Li system.In addition, not containing more preferably 2.14～2.44 scope, more preferably 2.14～2.30 scope in Li system.

In addition, Li ₂o is the composition that makes the softening point reduction of glass, is containing Li ₂in the composition system of O, in order to obtain the good connectivity of burning till, preferred Li ₂more than O is 0.6 % by mole and below 18 % by mole.Work as Li ₂o is during lower than 0.6 % by mole, and softening point is too high and then become insufficient to the aggressivity of antireflection film.On the other hand, when surpassing 18 % by mole, because alkali stripping and aggressivity became strong, electrical characteristics reduce on the contrary.By the way, so Li is owing to promoting that diffusion is impurity conventionally concerning semiconductor, because existence makes the tendency of characteristic reduction, so wish to avoid in semiconductor applications.Especially, while conventionally containing Li in the situation that Pb amount is many, there is the aggressivity strong and unmanageable tendency that became.Yet, in solar cell purposes as described above, even if use containing the glass of Li, do not confirm that characteristic reduces, and confirms on the contrary: by containing in right amount, can improve and burn till connectivity, thereby characteristic improves yet.In addition, Li is donor element, also has the effect that reduces contact resistance.And, by being made as the composition that contains Li, also having the compositing range that can access the good glass that burns till connectivity, become large advantage.Li ₂o amount is the scope of 1～15 % by mole more preferably.

In addition, due to P ₂o ₅be with respect to the alms giver of n layer and to the impurity solubility of Si up to 2 * 10 ^-21atm/cm ³, so there is the ohmic contact that more easily obtains substrate and sensitive surface electrode, the advantage that can further reduce contact resistance in left and right.Owing to working as P ₂o ₅the tendency that exists softening point to uprise while becoming many, so preferably: P ₂o ₅amount containing being to be 4.0 % by mole below 6.0 % by mole below, in not being containing Li in Li system.In addition, containing in Li system more preferably below 2.0 % by mole, in not containing Li system more preferably in the scope of 1.0～4.0 % by mole, be particularly preferably in the scope of 1.0～2.0 % by mole.

By the way, in the element cell of high film resistor that forms shallow emitter, preferably: for example, by Si ₃n ₄the gauge of the antireflection film forming is made as 80nm left and right, the erosion amount of electrode is controlled to the scope of 90～110nm, with the precision of 20nm, controls.Yet such control is extremely difficult, in order to ensure conducting, have to control to become corrode a little excessive state.When containing donor element as described above in glass, the output causing because this erosion is excessive reduces suppressed because of alms giver's effect, so become, easily obtains ohmic contact.

In addition, as described above in the situation that frit is to be mixed with the softening point frit of different glass of more than two kinds mutually, preferred: the glass of low softening point to be relatively made as to the lead glass (hereinafter referred to as " erosion glass ") containing Sn, the glass of high softening-point to be relatively made as to alms giver and to measure many glass (hereinafter referred to as " alms giver's glass ").As alms giver, preferred P, but due to when erosion glass is the composition that contains more P, softening point easily uprises, so be difficult to obtain best composition.If mix as mentioned above glass of more than two kinds, can fully obtain the additive effect of aforesaid Sn, and also can obtain sufficient alms giver's compensation effect.Preferred: alms giver's glass is 10～30 % by weight left and right of total glass amount.In addition, alms giver's glass is preferred: softening point, than corroding high 50～200 ℃ of left and right of glass, can obtain alms giver's glass of the FF value of 50～73 left and right in paste for use in electrode in the situation that of use separately.If the sintering that the softening point of alms giver's glass is set in to Ag powder starts near temperature,, supplying with alms giver's glass to the part that can not be corroded by the lead glass of low softening point antireflection film, make it corrode this antireflection film, can obtain more stable ohmic contact.Containing Li system, in the arbitrary system containing Li system, the softening point that corrodes glass is all preferably in the scope of 350～500 ℃, be particularly preferably in the scope of 400～450 ℃.In addition, the softening point of alms giver's glass is preferably in the scope of 450～650 ℃, is particularly preferably the scope of 500～600 ℃.In addition, preferably alms giver's glass is the glass that leakage current is low.In addition, when making alms giver's glass be the composition that contains sulphur, because the surface tension of glass reduces, thus to electrode-substrate interface, supply with rapidly aspect glass effective.

In addition, above-mentioned each composition and each composition described later in glass with what kind of form contain may not be difficult to specific, but their ratio is all defined as the value converting after (being converted into oxide) by oxide.

In addition, preferred: above-mentioned glass is with Al in containing Li system ₂o ₃be 9 % by mole of following, TiO ₂be that 6 % by mole of following, ZnO are 15 % by mole of following scopes, in not containing Li system with Al ₂o ₃be 6 % by mole of following, TiO ₂be that 3 % by mole of following, ZnO are that 4.5 % by mole of following scopes contain Al ₂o ₃, TiO ₂, at least one the glass in ZnO.The composition that contains them if be made as, has advantages of and can reduce PbO amount.In addition, also have advantages of and can improve parallel resistance, reduce leakage current and can increase open circuit voltage and short circuit current.On the other hand, due to the tendency that also has their leakage current just more increases more at most, so preferably they using above-mentioned amount as the upper limit.

In addition Al, ₂o ₃for obtaining the effective composition of stability of glass, when containing Al ₂o ₃time there is the viscosity of glass, the tendency that softening point uprises, and existence makes series resistance reduce, increase Fill factor, and firing range becomes large tendency, but as mentioned above, also have and leakage current is increased and when becoming the effect that makes on the contrary open circuit voltage decline when excessive, so containing in Li system more preferably below 7 % by mole, more preferably below 6 % by mole.In addition, not containing in Li system more preferably below 6 % by mole, more preferably below 1 % by mole.

In addition, although TiO ₂be improved the tendency of FF value, but when excessive interpolation, softening point rises, and then the tendency that exists contact resistance to uprise, and as mentioned above, also have the effect that leakage current is increased, so TiO ₂amount is containing in Li system more preferably below 3 % by mole, in not containing Li system more preferably containing TiO ₂composition.

In addition, because the amount as ZnO is when excessive, open circuit voltage reduces, so ZnO amount is further preferably limited to below 12 % by mole in containing Li system, is more preferably limited to below 8.5 % by mole.In addition, in not containing Li system, be further preferably limited to below 2 % by mole.

In addition, preferred: above-mentioned glass is all with the scope below 0.5 % by mole, to contain ZrO containing Li system with in not containing the arbitrary system in Li system ₂glass.Although ZrO ₂be the composition that improves the chemical durability of glass and improve FF value, but be not essential composition in the present invention, also can not contain.

In addition, preferred: above-mentioned glass is with the scope below 15 % by mole, to contain Bi in containing Li system ₂o ₃, in not containing Li system, with the scope below 2 % by mole, contain Bi ₂o ₃glass.Due to Bi ₂o ₃be the composition that reduces the softening point of glass, can realize easy fired, therefore preferably contain.Bi ₂o ₃amount is containing in Li system more preferably below 12 % by mole, more preferably below 3 % by mole.In addition, in not containing Li system, more preferably do not contain the composition of Bi.

In addition, preferred: above-mentioned glass is with the scope below 1 % by mole, to contain Na in containing Li system ₂the glass of O.Na ₂o and Li ₂o is the composition that makes the softening point reduction of glass equally, but when surpassing 1 % by mole, softening point becomes too low value, corrodes and becomes excessive, so leakage current increases, the electrical characteristics of solar cell become insufficient.

In addition, preferred: above-mentioned glass is with the scope below 2 % by mole, to contain SO in containing Li system ₂, containing in Li system, with the scope below 0.5 % by mole, do not containing SO ₂glass.Due to SO ₂viscosity when glass has been softened reduces and then surface tension is reduced, so glass ingredient is supplied to electrode-substrate interface rapidly, so Gai interface can form thin glassy layer uniformly, can obtain good electrical characteristics.Therefore, the control of the intrusion amount of electrode material becomes easily, thereby can more easily obtain ohmic contact.

In addition, preferred: above-mentioned glass is with the scope below 2 % by mole, to contain Ag in containing Li system ₂o, containing in Li system, with the scope below 0.5 % by mole, do not containing Ag ₂the glass of O.Together with the Ag that enters into glass structure with sintering process at electrode due to the Ag initially containing in glass structure, be reduced and recrystallization, so can further reduce series resistance.In addition, when short high speed of the time by high temperature keeping, burn till and carry out electrode while forming, exist Ag to the inadequate situation that becomes of the dissolving in glass, but by initially there being Ag in glass structure, having the process margin (process margin) of burning till to become large effect.

In addition, the average grain diameter of above-mentioned frit (D50) is in the scope of 0.3～3.0 μ m.When the average grain diameter of frit is too small, when the burning till of electrode melting too early, so electrical characteristics decline, if but 0.3 μ m can obtain appropriate meltbility above, so further improved electrical characteristics.And, owing to being difficult to produce cohesion, so can obtain further good dispersiveness when sticking with paste modulation.In addition, in the situation that the average grain diameter of frit is remarkable larger than the average grain diameter of electroconductive powder, the overall dispersiveness of powder also reduces, if but below 3.0 μ m, can access better dispersiveness.And, can access the further meltbility of glass.Therefore, for obtaining better ohmic contact, preferred above-mentioned average grain diameter.

In addition, the average grain diameter of above-mentioned frit is the value of utilizing air permeability method to obtain.Air permeability method refers to, for example, according to fluid (air), with respect to the permeability of powder layer, measures the method for the specific area of powder.Become the basic infiltration surface area that means all particles that forms powder layer of this assay method and pass through the flow velocity of fluid there and Kang Caini-Kaman (Kozeny-Carmann) formula of the relation of Pressure Drop, mensuration, for flow velocity and the Pressure Drop of the powder layer of filling under the condition definite by device, is obtained the specific area of sample.The method is that the gap of filled powder particle is judged to be to pore, obtains the method for the infiltration surface area of the population that becomes resistance in air stream, conventionally shows the little value of specific area that Billy obtains with gas adsorption method.Can calculate the average grain diameter of having supposed powder particle according to the above-mentioned specific area of obtaining and particle density.

In addition, preferred: above-mentioned electroconductive powder is the silver powder of average grain diameter (D50) in the scope of 0.3～3.0 μ m.As electroconductive powder, also can use copper powders, nickel by powder etc., but because silver powder obtains high conductivity, therefore most preferably.In addition, if the average grain diameter of silver powder obtains better dispersiveness at 3.0 μ m with next, so can obtain higher conductivity.In addition, if more than 0.3 μ m, thereby suppress cohesion, obtain better dispersiveness.In addition, due to significantly high lower than the silver powder price of 0.3 μ m, so from manufacturing cost aspect, more than being also preferably 0.3 μ m.In addition, if the average grain diameter of electroconductive powder, frit all below 3.0 μ m, is stopped up even if have advantages of to be also difficult to produce in the situation that utilizing thread pattern to print to form electrode.

In addition, above-mentioned silver powder without particular limitation of, in the situation that use the powder of any shapes such as spherical, flakey can both obtain and can realize the such basic effect of the present invention of graph thinning under the state that keeps conductivity.But, in the situation that having used spherical powder, printing is excellent, and the filling rate of the silver powder in coated film uprises, so the silver high with having used conductivity complements each other, compare with having used the situation of the silver powder of other shapes such as flakey, the conductance of the electrode being generated by this coated film uprises.Therefore, owing to can make more refinement of line width under the state of guaranteeing required conductivity, so particularly preferably.

In addition, preferred: above-mentioned electrode of solar battery paste composite, in the scope that the viscosity under 25 ℃-20rpm is 150～250Pas, ratio of viscosities (that is, ［ viscosity during 10rpm ］/［ viscosity during 100rpm ］) is 3～8.The paste by use with such viscosity characteristics, when extruding, be well suited for ground lowering viscousity and see through screen cloth, thereby after seeing through, it reverts to the expansion that high viscosity suppresses printing width, so easily see through silk screen, do not produce obstruction etc., under the state that guarantees printing, easily obtain thread pattern.The viscosity of paste composite is the scope of 180～220Pas more preferably, and ratio of viscosities is 3.2～6.5 scope more preferably.In addition, in design live width, be that in the graph thinning below 100 μ m, preferred viscosities ratio is 4～6.

In addition, even if thicken thickness, so that reduce live width, also can guarantee sectional area, for example, also can thicken plate making emulsion thickness, improve tension force, reduce wire diameter and extend bore etc.Yet, when thickening emulsion thickness, due to misplacing of stencil variation, so cannot obtain the stability of printed patterns shape.In addition, when improving tension force or reducing wire diameter, screen cloth easily stretches, so exist, is difficult to guarantee size and dimension precision, and the problem of the durability of plate making decline.And, so make also thickening of useless busbar because the width setting with thick thickens thickness, therefore also exist waste of material to become many problems.

In addition, preferred: above-mentioned electrode of solar battery paste composite is the paste composite that contains above-mentioned electroconductive powder, contains above-mentioned vehicle with the ratio in the scope of 3～20 weight portions with the ratio in the scope of 64～90 weight portions.Thus, obtain can printing good, can easily to form the electrode that line width is thin, conductivity is high paste composite.

In addition, preferred: above-mentioned conductive paste composition is the paste composite that contains above-mentioned frit with the scope of 1～10 weight portion with respect to above-mentioned electroconductive powder 100 weight portions.If contain 1 weight portion, can obtain above sufficient aggressivity (burning till connectivity), therefore can obtain good ohmic contact.In addition, if be limited to below 10 weight portions, be difficult to form insulating barrier, so can obtain sufficient conductivity.With respect to the amount of glass of 100 weight portion electroconductive powders more preferably 1～8 weight portion, more preferably 1～7 weight portion.

In addition, form the lead glass of above-mentioned frit, can synthesize by can carry out vitrified various raw material in above-mentioned compositing range, such as listing oxide, carbonate, nitrate etc., for example, as Sn source, can use tin monoxide (SnO), as Li source, can use lithium carbonate (Li ₂cO ₃), as P source, can use ammonium dihydrogen phosphate (NH ₄h ₂pO ₄), as Si source, can use silicon dioxide (SiO ₂), as B source, can use boric acid (B ₂o ₃), as Pb source, can use red lead (Pb ₃o ₄).

In addition, in the situation that be made as the composition that also contains other compositions such as Al, Ti, Zn, Zr except mentioned component, as long as use oxide such as them, hydroxide, carbonate, nitrate etc.

In addition, form the above-mentioned glass of conductive paste of the present invention, can contain other various glass constituents and/or additives in the scope of not damaging its characteristic.For example, also can contain Ca, Mg, K, Ba, Sr etc.They can be for example to add up to 30 % by mole of following scopes to contain.

Accompanying drawing explanation

Fig. 1 (a) and (b) are for the schematic diagram of separating out the conductive path to sensitive surface electrode in pattern and each situation of recrystallization Ag is described.

Fig. 2 means to possess the schematic diagram of cross-section structure that the paste for use in electrode composition of one embodiment of the present of invention is applied to the solar module of the solar cell that sensitive surface electrode forms.

Fig. 3 means the figure of an example of sensitive surface electrode pattern of the solar cell of Fig. 2.

Fig. 4 is for illustrating to the figure corresponding with Fig. 1 of the conductive path of the sensitive surface electrode of the solar cell of Fig. 2.

Description of reference numerals

10: solar cell, 12: solar module, 14: encapsulant, 16: watch crystal, 18: diaphragm, 20: silicon substrate, 22:n layer, 24:p ⁺layer, 26: antireflection film, 28: sensitive surface electrode, 30: backplate, 32: sensitive surface, 34: whole electrode, 36: band electrode, 40: glassy layer, 42: recrystallization Ag, 44: recrystallization Ag, 46: silver particles, 50: silicon substrate, 52: sensitive surface electrode, 54: glassy layer, 56: recrystallization Ag, 58: silver particles, 60: recrystallization Ag.

Embodiment

Below, with reference to accompanying drawing, describe one embodiment of the present of invention in detail.In addition, in following embodiment, figure is suitably simplified or is out of shape, the size ratio of each several part and shape etc. may not be described exactly.

Fig. 2 schematically illustrates the figure of cross-section structure that the silicon of conductive composition that possesses application one embodiment of the present of invention is the solar module 12 of solar cell 10.In Fig. 2, solar module 12 possesses: above-mentioned solar cell 10, by the encapsulant of its sealing 14, be located at watch crystal 16 on encapsulant 14, diaphragm (being backboard) 18 for arranging from rear side protection solar cell 10 and encapsulant 14 in sensitive surface side.Above-mentioned encapsulant 14 consists of for example EVA, is suitably mixed with crosslinking agent, ultra-violet absorber, bonding protective agent etc., so that have sufficient weatherability.In addition, said protection film 18 is by such as fluororesin, PETG (PET) resin or be fitted with the diaphragm that the film etc. of the resin molding consisting of PET, EVA etc. of many pieces forms, and has high weather resistance, water-vapor barrier etc.

In addition, above-mentioned solar cell 10 for example possesses as the silicon substrate 20 of p-type poly semiconductor, lower surface forms respectively thereon n layer 22 and p ⁺layer 24, the antireflection film 26 forming on this n layer 22 and sensitive surface electrode 28 and at this p ⁺the backplate 30 forming on layer 24.The gauge of above-mentioned silicon substrate 20 is for example 100～200 μ m left and right.

Above-mentioned n layer 22 and p ⁺layer 24 is by the upper and lower surface at silicon substrate 20, to form the layer that impurity concentration is high to arrange, and the gauge of this high concentration layer is that n layer 22 is for example 70～100nm left and right, p ⁺layer 24 is for example 500nm left and right.Although n layer 22 is to be 100～200nm left and right in solar cell at general silicon, becomes in the present embodiment thinner than it, forms the structure that is called as shallow emitter.In addition the alloy that in n layer 22, contained impurity is N-shaped, for example phosphorus (P), p, ⁺alloy, for example aluminium (Al), boron (B) that in layer 24, contained impurity is p-type.

In addition, above-mentioned antireflection film 26 is for example by silicon nitride (Si ₃n ₄) etc. the film that forms, for example optical thickness, for example 80nm left and right by 1/4 left and right with visible wavelength arranges, and is configured to below 10%, the extremely low reflectivity of 2% left and right for example.

In addition, above-mentioned sensitive surface electrode 28, for example, be that the thick film conductor by the same gauge forms, as shown in Figure 3, sensitive surface 32 roughly on whole to form the flat shape setting of the comb shape with many thin thread parts.

Above-mentioned thick film conductor, is by with respect to 100 weight portion Ag, and for example, in the scope that contains 1～10 weight portion, the thick film silver of the glass of 4.5 weight portions left and right forms, this glass is containing the lead glass of Li or not containing the lead glass of Li.

Containing the composition in the situation of the lead glass of Li, by the value of carrying out after oxide conversion, be that the lead glass that contains following material: PbO is, 51.0 % by mole of left and right for example in the scope of 24～64 % by mole, B ₂o ₃be in the scope of 1～18 % by mole, 6.0 % by mole of left and right for example, SiO ₂be in the scope of 11～40 % by mole, 24.0 % by mole of left and right for example, Al ₂o ₃be in the scope of 0～9 % by mole, 3.0 % by mole of left and right for example, Li ₂o is in the scope of 0.6～18 % by mole, 3.0 % by mole of left and right for example, TiO ₂be in the scope of 0～6 % by mole, 3.0 % by mole of left and right for example, ZnO is in the scope of 0～15 % by mole, 5.5 % by mole of left and right for example, ZrO ₂be in the scope of 0～0.5 % by mole, for example 0 % by mole, P ₂o ₅be in the scope of 0～6 % by mole, 2.0 % by mole of left and right for example, Bi ₂o ₃be in the scope of 0～15 % by mole, for example 0 % by mole, Na ₂o is in the scope of 0～1 % by mole, for example 0 % by mole, SnO is in the scope of 0.5～20 % by mole, 2.0 % by mole of left and right for example, SO ₂be in the scope of 0～2 % by mole, for example 0.5 % by mole of left and right, Ag ₂o is in the scope of 0～2 % by mole, for example 0 % by mole.In addition, in this lead glass, contain PbO and SiO ₂make that Pb/Si mol ratio becomes in 0.6～5.0 scope, the ratio of 2.13 left and right for example.

In addition, not containing the composition in the situation of the lead glass of Li, by the value of carrying out after oxide conversion, be that the lead glass that contains following material: PbO is, 62.0 % by mole of left and right for example in the scope of 55～65 % by mole, B ₂o ₃be in the scope of 1～8 % by mole, 4.0 % by mole of left and right for example, SiO ₂be in the scope of 21～36 % by mole, 27.0 % by mole of left and right for example, Al ₂o ₃be in the scope of 0～6 % by mole, 1.0 % by mole of left and right for example, TiO ₂be in the scope of 0～3 % by mole, for example 0 % by mole, ZnO is in the scope of 0～4.5 % by mole, 2.0 % by mole of left and right for example, ZrO ₂be in the scope of 0～0.5 % by mole, for example 0 % by mole, P ₂o ₅be in the scope of 0～4 % by mole, 2.0 % by mole of left and right for example, Bi ₂o ₃be in the scope of 0～2 % by mole, for example 0 % by mole, SnO is in the scope of 0.5～12 % by mole, 2.0 % by mole of left and right for example, SO ₂be in the scope of 0～0.5 % by mole, for example 0 % by mole, Ag ₂o is in the scope of 0～0.5 % by mole, for example 0 % by mole.In addition, in this lead glass, contain PbO and SiO ₂for example, so that Pb/Si mol ratio becomes in 1.5～2.9 scope, the ratio of 2.30 left and right.

In addition, the gauge of above-mentioned conductor layer is for example in the scope of 20～30 μ m, 25 μ m left and right for example, and the width dimensions separately of thin thread part is for example in the scope of 60～130 μ m, for example have fully high conductivity during 80 μ m left and right.

In addition, above-mentioned backplate 30, consists of whole electrode 34 and band electrode 36, and described whole electrode 34 is at p ⁺on layer 24, roughly whole ground coating take that thick-film material that aluminium is conductor composition forms, and described band electrode 36 is on this whole electrode 34, to be the electrode consisting of thick film silver that applies bandedly and form.This band electrode 36 is the electrodes that arrange for brazing solder band 38 on electrode 30 overleaf and wire etc.On above-mentioned sensitive surface electrode 28, be also similarly deposited with scolder band 38 with rear side.

The solar cell 10 of the present embodiment, sensitive surface electrode 28 consists of thick film silver, described thick film silver has aforesaid composition, and with the scope of 1～10 weight portion, contain lead glass with respect to 100 weight portion silver, described lead glass be with the ratio in the scope of 0.5～20 % by mole contain SnO containing the lead glass of Li or with the ratio in the scope of 0.5～12 % by mole contain SnO not containing the lead glass of Li, so connecting while forming sensitive surface electrode 28 by burning till, Ag meltage in glass becomes fully many, and Ag nucleus has occurred appropriateness.Therefore, producing in conjunction with being also difficult to again of the low and electronics that produces of series resistance, so FF value and current value are larger, and then has the performance that conversion efficiency is high.In addition, because erosion amount is controlled as about 90～110nm, be controlled as than the gauge maximum of antireflection film 18 degree of depth of large 30nm left and right only, so although line width is reduced to 80 μ m left and right, and n layer 22 between also can obtain good ohmic contact, contact resistance step-down.

Fig. 4 is for the schematic diagram from silicon substrate 20 near surfaces of above-mentioned solar cell 10 to the conductive path of sensitive surface electrode 28 is described.Between silicon substrate 20 and sensitive surface electrode 28, when burning till perforation, formed glassy layer 40.When the glass that contains Sn by selection as in this embodiment forms, while having realized appropriate Ag meltage, at appropriate nano level recrystallization Ag42 and the recrystallization Ag44 larger than recrystallization Ag42 of generating of the interior difference of above-mentioned glassy layer 40.Such recrystallization Ag42,44 generation state are the states of the centre of situation that the Ag solubility shown in above-mentioned Fig. 1 (a) and (b) is large and little situation, and conductive path also becomes the sample state that is mixed with them.

; electronics in silicon substrate 20 interior generations; arrive recrystallization Ag42 in glassy layer 40, at 44 o'clock; in the direction along aspect (Fig. 4's is horizontal); show greatly glass-Ag-by Ag-... the jump conduction in path be main; but the mobile route from glassy layer 40 to sensitive surface electrode 20 (Fig. 4 longitudinally) in addition from recrystallization Ag42, the 44 direct conduction to the silver particles 46 in sensitive surface electrode 20, and be take the latter as main except the conduction of jumping.Therefore, because horizontal electrical conductivity is not by silicon substrate 20, so be difficult to produce combination again, and, because electrical conductivity longitudinally becomes low resistance because of direct conduction, so as described above, can obtain series resistance low and be also difficult to generate the solar cell 10 of combination again.

And, the sensitive surface electrode 42 of the present embodiment, as described above amount of glass is made as to a small amount of of 4.5 weight portion left and right, therefore there is high conductivity, therefore,, although thickness and live width all reduce, line resistance is also low, so complement each other with contact resistance is low, the light-to-current inversion efficiency of solar cell 10 is improved.

Sensitive surface electrode 20 as described above, is to use the paste for use in electrode for example consisting of conductor powder, frit, vehicle, solvent, by the perforation method of burning till of knowing, forms.Below, illustrate and comprise that this sensitive surface electrode is formed on an example of the manufacture method of interior solar cell 10.

First, make above-mentioned frit.Prepare respectively tin monoxide (SnO) as Sn source, lithium carbonate (Li ₂cO ₃) as Li source, ammonium dihydrogen phosphate (NH ₄h ₂pO ₄) as P source, silicon dioxide (SiO ₂) as Si source, boric acid (B ₂o ₃) as B Yuan, red lead (Pb ₃o ₄) as Pb source, aluminium oxide (Al ₂o ₃) as Al source, titanium oxide (TiO ₂) as Ti source, zinc oxide (ZnO) as Zn source; Etc., weigh and allocate the suitable composition that makes to become in aforesaid scope.They are dropped in crucible, and the temperature in the scope with corresponding 900～1200 ℃ of composition is carried out the melting about 30 minutes～1 hour, by chilling, makes its vitrifying.Use the suitable reducing mechanism such as planetary mill, ball mill to pulverize in this glass.Average grain diameter after pulverizing (D50) is for example 0.3～3.0 μ m left and right.In addition, the average grain diameter at above-mentioned frit end is used air permeability method to calculate.

On the other hand, as conductor powder, for example, prepare the commercially available spherical silver powder in scope that average grain diameter (D50) is 0.3～3.0 μ m.By using fully little silver powder of such average grain diameter, can improve the conductance of filling rate and then the raising conductor of the silver powder in coated film.In addition, above-mentioned vehicle is to make organic bond be dissolved in the vehicle that organic solvent modulates, and as organic solvent, can use for example acetate of butyl carbitol, as organic bond, can use for example ethyl cellulose.The ratio of the ethyl cellulose in vehicle is for example 15 % by weight left and right.In addition, with the solvent that vehicle is turned up the soil respectively and added, for example, be acetate of butyl carbitol.That is, although be not limited thereto, can be, the solvent same with the solvent phase using in vehicle.This solvent adds to adjust the object of the viscosity of sticking with paste.

Prepare respectively above paste raw material, the ratio that the conductor powder of for example take is 3～5 % by weight as 1～6 % by weight, vehicle as 5～14 % by weight, solvent as 77～90 % by weight, frit weighs, use after the mixing such as mixer, for example, utilize three-roll mill to carry out dispersion treatment.Thus, obtain above-mentioned paste for use in electrode.

Modulator electrode, with sticking with paste, on the other hand, by suitable silicon substrate, adopts the method for knowing such as thermal diffusion method, Implantation etc. to spread or implanted dopant as described above, forms said n layer 22 and p ⁺layer 24, makes above-mentioned silicon substrate 20.Then, on above-mentioned silicon substrate 20, utilize the plasma CVD such as PE-CVD() etc. suitable method form silicon nitride film, above-mentioned antireflection film 26 is set.

Then,, on above-mentioned antireflection film 26, utilize the pattern shown in above-mentioned Fig. 3 by above-mentioned paste for use in electrode silk screen printing.By its for example 150 ℃ be dried, and then temperature in near-infrared stove in the scope of 700～900 ℃ implements to burn till processing.Thus, glass ingredient in this sintering process in paste for use in electrode makes antireflection film 26 meltings, this paste for use in electrode destroys antireflection film 26, so obtain being i.e. electrically connected to of silver and n layer 22 of conductor composition in paste for use in electrode, obtain like that as shown in Figure 2 above the ohmic contact of silicon substrate 20 and sensitive surface electrode 28.Sensitive surface electrode 28 forms in this wise.

In addition, above-mentioned backplate 30 can form after above-mentioned operation, but also can side by side burn till and form with sensitive surface electrode 28.When forming backplate 30, at the whole back side of above-mentioned silicon substrate 20, utilization such as silk screen print method etc. comes aluminium coat to stick with paste, and implements to burn till processing, forms thus above-mentioned whole the electrode 34 consisting of aluminium thick film.And then by the surface at this whole electrode 34, use silk screen print method etc. is to apply above-mentioned paste for use in electrode and implement burns till processing, thereby forms above-mentioned band electrode 36 bandedly.Thus, formed by covering whole electrode 34 at the whole back side and being in its surperficial part the backplate 30 that banded the band electrode 36 arranging forms, thereby obtained above-mentioned solar cell 10.In above-mentioned operation, by burn till to manufacture in the situation that simultaneously, before the burning till of sensitive surface electrode 20, implement printing treatment.

Glass is formed and carries out various changes, according to above-mentioned manufacturing process, manufacture solar cell 10, with commercially available solar simulator, measure its output, together with the result of appraisal curve factor FF value, conversion efficiency Eff and leakage current Iv is formed with glass, be illustrated in table 1～table 4.Table 1(No.1～12) used and do not contained the lead glass of Li, table 2,3(No.13～82) used the lead glass containing Li, table 4 utilization is discussed best composition containing Bi system.FF value determines whether and obtains good ohmic contact, and usually, if solar cell FF value is more than 70 just can use, but that yes is more high better, in the present embodiment, by FF value be greater than 75 be judged to qualified.In addition, conversion efficiency is high for well, and conversion efficiency is there is no the decline of current value etc., synthetically judge the project whether conversion efficiency good, conversion efficiency more than 17% be judged to qualified.In addition, leakage current is low for well, and leakage current becomes whether cause that electrode invades the determinating reference of pn knot.The numerical value of leakage current when 10V be below 0.1A, be judged to ◎, below 0.2A, be judged to zero, below 0.5A, be judged to △, surpass 0.5A and be judged to *.

Table 1 forms (mol%)

Table 2 forms (mol%)

Table 3 forms (mol%)

Table 4 forms (mol%)

In addition, each sample is to use the frit of the equal particle diameter 1.5 μ m of spherical Ag powder peace of average grain diameter 1.6 μ m to make.Allotment ratio is usingd Ag powder 86 % by weight, frit 4 % by weight, vehicle 6 % by weight, solvent 4 % by weight as substantially, in order to make printing identical, suitably adjusts vehicle amount and quantity of solvent, so that the viscosity under 25 ℃-20rpm is 200～220Pas.In addition, the plate making while forming sensitive surface electrode 28, is on the SUS325 of wire diameter 23 μ m screen cloth processed, to be provided with the thick emulsion of 20 μ m to form.In addition, set printing condition so that the width dimensions of grid line is 80 μ m.In addition, use 5 inches of monocrystal substrates, the film resistor of substrate adopts 90 ± 10 Ω/ to evaluate.

State in the use in the evaluation of the lead glass that does not contain Li shown in table 1, No.2～4,6～11st, embodiment, other (No.1,5,12) are comparative examples.In this table 1, as embodiment, show at the PbO-B that forms basic framework ₂o ₃-SiO ₂middlely added the 4 compositions systems of SnO and also added therein Al ₂o ₃, TiO ₂, ZnO, ZrO ₂, P ₂o ₅, Bi ₂o ₃, SO ₂, Ag ₂the glass of 5 several～9 composition systems of composition system in O.

Comparative examples No.1 and embodiment No.2～4 etc. are 61.0～68.0 % by mole in Pb amount, B amount is 4.0～8.0 % by mole, Si amount is 22.0～26.0 % by mole, Al amount is 0 % by mole, Ti amount is 0～3.0 % by mole, Zn amount is 0～1.5 % by mole, Zr amount is 0～0.5 % by mole, P amount is 0～4.0 % by mole, Bi amount is 0 % by mole, Sn amount is 0.5～12.0 % by mole, S amount is 0～0.5 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 2.35～2.96 scope, if Pb amount is 61.0～65.0 % by mole, B amount is 4.0～8.0 % by mole, Si amount is 22.0～26.0 % by mole, Ti amount is 0～3.0 % by mole, Zn amount is 0 % by mole, Zr amount is 0～0.5 % by mole, P amount is 0～4.0 % by mole, Sn amount is 0.5～12.0 % by mole, S amount is 0～0.5 % by mole, Pb/Si is than the scope that is 2.35～2.82, about Pb amount, be below 65.0 % by mole, obtained FF value fully up to more than 75, Eff is fully up to more than 17.0%, Iv is little characteristic to 0.2A fully.Also large to 2.96 comparative example No.1 at nearly 68.0 % by mole of Pb amounts, result Pb/Si, become FF value and be 74, Eff is 16.7%, Iv is also the result below 0.5A.

In addition, as shown in embodiment No.3, even if B amount increases to 8.0 % by mole, P amount, increase to 4.0 % by mole, Sn amount is reduced to 0.5 % by mole, has also obtained FF value and be 76, Eff is 17.1%, Iv is the good result below 0.2A.

In addition, comparative example No.4, 6 and comparative example No.5, in Pb amount, be 59.5～62.0 % by mole, B amount is 4.0～6.0 % by mole, Si amount is 20.0～22.0 % by mole, Al amount is 0～3.0 % by mole, Ti amount is 0～3.0 % by mole, Zn amount is 0～3.0 % by mole, Zr amount is 0 % by mole, P amount is 0～2.0 % by mole, Bi amount is 0 % by mole, Sn amount is 2.0～15.0 % by mole, S amount is 0～0.5 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 2.82～3.00 scope, even if Pb amount is 59.5～62.0 % by mole, B amount is 4.0～6.0 % by mole, Si amount is 21.0～22.0 % by mole, Al amount is 0～3.0 % by mole, Ti amount is 0～3.0 % by mole, Zn amount is 0～3.0 % by mole, P amount is 0～2.0 % by mole, Sn amount is 2.0～12.0 % by mole, S amount is 0～0.5 % by mole, Pb/Si is than being in 2.82～2.83 scope, and Si amount reduces to 21.0 % by mole, and Sn amount increases to 12.0 % by mole, and result Pb/Si increases to 2.83, and it is more than 75 also having obtained FF value, Eff is more than 17.0%, Iv is the good result below 0.2A, but reduces to 20.0 % by mole when Si measures, when Sn amount increases to 15.0 % by mole, becoming FF value is 72, Eff is that 16.4%, Iv also increases to result more than 0.5A.In addition,, as shown in No.4, even only there are the 4 compositions systems of essential composition Pb in the present invention, B, Si, Sn, also can access sufficient result.

In addition, as shown in embodiment No.7～10, for Pb amount being that 58.0～62.0 % by mole, B amount are that 4.0 % by mole, Si amount are that 25.0～29.0 % by mole, Al amount are that 1.0～6.0 % by mole, Ti amount are 3.0 % by mole below, Zn amount is 2.0 % by mole below, Zr amount is that 0 % by mole, P amount are that 1.0～2.0 % by mole, Bi amount are 2.0 % by mole below, Sn measure be 1.0～2.0 % by mole, S measure be below 0.5 % by mole, Ag is when measuring and being the composition below 0.5 % by mole, obtained FF value and be 77～78, Eff is 17.4～17.6%, Iv is the excellent characteristic below 0.2A.Special Pb amount is that 62.0 % by mole, Si amount are that 27.0～29.0 % by mole, Al amount are that 1.0 % by mole, Ti amount are that 0 % by mole, Zn amount are that 1.0～2.0 % by mole, P amount are that 1.0～2.0 % by mole, Bi amount are the No.8,9 of 0 % by mole, has obtained FF value and be 78, Eff is 17.6%, Iv is the high characteristic below 0.1A.In addition, No.8, firing range is also the result of the wide region of 720～770 ℃, when the paste that does not contain the lead glass of Li for having used forms, becomes the most excellent result.

In addition, comparative example No.11 and comparative example No.12, be 53.0～55.0 % by mole in Pb amount, B amount is 1.0～4.0 % by mole, Si amount is 36.0～37.0 % by mole, Al amount is 1.0 % by mole, Ti amount is 0 % by mole, Zn amount is 2.0～4.5 % by mole, Zr amount is 0～0.5 % by mole, P amount is 1.0 % by mole, Bi amount is 0 % by mole, Sn amount is 1.0 % by mole, S amount is 0.5 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 1.43～1.53 scope, even Pb amount is 55.0 % by mole, B amount is 1.0 % by mole, Si amount is 36.0 % by mole, Zn amount is 4.5 % by mole, Zr amount is 0 % by mole, Pb/Si is than the composition that is 1.53, that is, Pb amount reaches 55.0 % by mole, B amount reduces to 1.0 % by mole, Si amount reaches 36.0 % by mole, Zn amount increases to 4.5 % by mole, and result Pb/Si reduces to 1.53, and also can access FF value is 76, Eff is 17.2%, Iv is the high characteristic below 0.2A, still, and when Pb amount reduces to 53.0 % by mole, Si amount increases to 37.0 % by mole, result Pb/Si reduces at 1.43 o'clock, becomes FF value and is reduced to 74, Eff is reduced to 16.7% result.

According to these evaluation results, in having used the electrode paste of the lead glass that does not contain Li, also have with the balanced of other elements and take into account, but be estimated as preferably: Pb amount is 55.0～65.0 % by mole, B amount is 1.0～8.0 % by mole, Si amount is 21.0～36.0 % by mole, Al amount is below 6.0 % by mole, Ti amount is below 3.0 % by mole, Zn amount is below 4.5 % by mole, Zr amount is 0.5 % by mole, P amount is below 4.0 % by mole, Bi amount is below 2.0 % by mole, Sn amount is 0.5～12.0 % by mole, S amount is below 0.5 % by mole, Ag amount is below 0.5 % by mole, Pb/Si is 1.5～2.9 scope.

In addition, according to the embodiment that has obtained good especially result, more preferably: Pb amount is that 55.0～62.0 % by mole, Si amount are that 25.0～29.0 % by mole, Al amount are that 1.0 % by mole of following, Ti amounts are that 0 % by mole, Zn amount are that 2.0 % by mole of following, Zr amounts are that 0 % by mole, P amount are that 1.0～4.0 % by mole, Bi amount are that 0 % by mole, Sn amount are the scope that 1.0～2.0 % by mole, Pb/Si are 2.1～2.5.In addition, can say particularly preferably: Pb amount is that 58.0～62.0 % by mole, Si amount are that 27.0～29.0 % by mole, P amount are the scope that 1.0～2.0 % by mole, Pb/Si are 2.1～2.3.

In addition, in having used the evaluation of the lead glass containing Li shown in above-mentioned table 2,3, No.14～20,22～28,31～42,44,45,48～63,65,66,69～81st, embodiment, other (No.13,21,29,30,43,46,47,64,67,68,82) are comparative examples.In these tables 2,3, as embodiment, show at the PbO-B that forms basic framework ₂o ₃-SiO ₂in added Li ₂the 5 compositions systems of O and SnO and also added therein Al ₂o ₃, TiO ₂, ZnO, ZrO ₂, P ₂o ₅, Bi ₂o ₃, Na ₂o, SO ₂, Ag ₂the glass of 6 several～12 composition systems of composition system in O.

Comparative examples No.13 and embodiment No.14 etc., in Pb amount, it is 64.0～65.0 % by mole, B amount is 4.0 % by mole, Si amount is 24.0～28.0 % by mole, Al amount is 0 % by mole, Li amount is 1.0 % by mole, Ti amount is 0～3.0 % by mole, Zn amount is 0～1.0 % by mole, Zr amount is 0～0.5 % by mole, P amount is 0～1.0 % by mole, Bi amount is 0 % by mole, Na amount is 0～0.5 % by mole, Sn amount is 0.5～2.0 % by mole, S amount is 0～0.5 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 2.29～2.71 scope, Pb amount is 64.0 % by mole if, Si amount is 28.0 % by mole, Ti amount is 0 % by mole, Zn amount is 1.0 % by mole, Zr amount is 0 % by mole, P amount is 1.0 % by mole, Na amount is 0 % by mole, Sn amount is 0.5 % by mole, S amount is 0.5 % by mole, Pb/Si is than the composition that is 2.29, , Pb amount is below 64.0 % by mole, obtained FF value fully high to more than 75, Eff is fully high to more than 17.0%, Iv is little characteristic to 0.2A fully.In Pb amount nearly in the comparative example No.13 of 65.0 % by mole, become FF value and be 74, Eff is 16.8%, Iv is also the result below 0.5A.

In addition, comparative example No.66 etc. and comparative example No.67, in Pb amount, it is 20.0～24.0 % by mole, B amount is 4.0～8.0 % by mole, Si amount is 32.0～34.0 % by mole, Al amount is 3.0 % by mole, Li amount is 12.0 % by mole, Ti amount is 3.0 % by mole, Zn amount is 15.0 % by mole, Zr amount is 0 % by mole, P amount is 0～2.0 % by mole, Bi amount is 0～5.0 % by mole, Na amount is 0～0.5 % by mole, Sn amount is 2.0 % by mole, S amount is 0～0.5 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 0.59～0.75 scope, Pb amount is 24.0 % by mole if, B amount is 4.0 % by mole, Si amount is 32.0 % by mole, P amount is 0 % by mole, Bi amount is 5.0 % by mole, Na amount is 0 % by mole, S amount is 0 % by mole, Pb/Si is than the composition that is 0.75, , Pb amount is more than 24.0 % by mole, obtained FF value fully high to more than 75, Eff is fully high to more than 17.0%, Iv is little characteristic to 0.5A fully.Few to the comparative example No.67 of 20.0 % by mole in Pb amount, become FF value and be 73, Eff to be 16.5% result.

In addition, comparative example No.44, 45 grades and comparative example No.43, 46, in Pb amount, it is 45.0～52.0 % by mole, B amount is 0～21.0 % by mole, Si amount is 19.0～28.0 % by mole, Al amount is 0～3.0 % by mole, Li amount is 6.0 % by mole, Ti amount is 0 % by mole, Zn amount is 0～13.0 % by mole, Zr amount is 0 % by mole, P amount is 0 % by mole, Bi amount is 0 % by mole, Na amount is 0 % by mole, Sn amount is 2.0～5.0 % by mole, S amount is 0 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 1.61～2.74 scope, in B amount, it is 1.0～18.0 % by mole, Si amount is 22.0～27.0 % by mole, Pb/Si than be 1.67～2.36 scope time obtained good result.; when B amount is the scope of 1.0～18.0 % by mole, obtained FF value and be more than 75, Eff is more than 17.0%, Iv is the good result below 0.5A; but the inadequate result that when B amount is 21.0 % by mole, 0 % by mole, become FF value and be 73～74, Eff is 16.5～16.6%.

In addition, comparative example No.31～42, 44, 45, 48, 49 and comparative example No.30, 47, in Pb amount, it is 40.0～55.0 % by mole, B amount is 1.0～18.0 % by mole, Si amount is 9.0～42.0 % by mole, Al amount is 0～6.0 % by mole, Li amount is 3.0～6.0 % by mole, Ti amount is 0～3.0 % by mole, Zn amount is 0～13.0 % by mole, Zr amount is 0 % by mole, P amount is 0～2.0 % by mole, Bi amount is 0～17.0 % by mole, Na amount is 0～0.5 % by mole, Sn amount is 1.0～10.0 % by mole, S amount is 0～0.5 % by mole, Ag amount is 0～2.0 % by mole, Pb/Si is than being in composition in 1.14～5.56 scope, in Si amount, it is 11.0～40.0 % by mole, Bi amount is 0～15.0 % by mole, Pb/Si than be 1.23～4.55 scope time obtained good result.That is,, when Si amount is the scope of 11.0～40.0 % by mole, obtained FF value and be 75～78, Eff is 17.0～17.9%, Iv is the good result below 0.5A.When Si amount is 9.0 % by mole, 42.0 % by mole, it is the inadequate result that FF value is 71～73, Eff is 15.8～16.5%.In addition, No.36, firing range is also extended to 720～780 ℃ together with No.18 described later, becomes the most excellent result in the paste that has used the lead glass that contains Li forms.Their Li amount is 1.0～3.0 % by mole, and the composition that contains a small amount of Li, and such with above-mentioned No.8 does not compare containing the composition of Li, and firing range is larger, thereby preferably.

In addition, comparative example No.14～20 grade and comparative example No.68, in Pb amount, it is 36.8～64.0 % by mole, B amount is 4.0～5.8 % by mole, Si amount is 25.5～31.0 % by mole, Al amount is 0～12.0 % by mole, Li amount is 1.0～12.0 % by mole, Ti amount is 0～2.0 % by mole, Zn amount is 0～2.5 % by mole, Zr amount is 0～0.5 % by mole, P amount is 0～2.0 % by mole, Bi amount is 0～2.0 % by mole, Na amount is 0～0.5 % by mole, Sn amount is 0.5～5.0 % by mole, S amount is 0～0.5 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 1.21～2.31 scope, in Pb amount, it is 55.0～64.0 % by mole, B amount is 4.0 % by mole, Al amount is 0～9.0 % by mole, Li amount is 1.0 % by mole, Ti amount is 0 % by mole, when Pb/Si is interior than the scope that is 1.97～2.31, obtained good result.That is the good result that, when Al amount is the scope of 0～9.0 % by mole, obtained FF value and be 75～78, Eff is 17.0～17.8%.Particularly Pb amount is that 59.5 % by mole, B amount are that 4.0 % by mole, Si amount are that 30.0 % by mole, Al amount are that 3.0 % by mole, Li amount are that 1.0 % by mole, P amount are that 1.0 % by mole, Sn amount are that 1.0 % by mole, S amount are the No.18 of 0.5 % by mole, the extremely result of excellence that obtained FF value and be 78, Eff is 17.8%.On the other hand, when being 12.0 % by mole, Al amount is the inadequate result that FF value is 74, Eff is 16.6%.

In addition, comparative example No.22～28, 50, 65 and comparative example No.21, 29, 64, in Pb amount, it is 38.0～53.5 % by mole, B amount is 6.0 % by mole, Si amount is 18.0～32.0 % by mole, Al amount is 0～3.0 % by mole, Li amount is 3.0～12.0 % by mole, Ti amount is 0～5.0 % by mole, Zn amount is 0～12.9 % by mole, Zr amount is 0～0.5 % by mole, P amount is 0～2.0 % by mole, Bi amount is 0 % by mole, Na amount is 0～0.5 % by mole, Sn amount is 0.1～25.0 % by mole, S amount is 0～1.0 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 1.19～2.78 scope, in Pb amount, it is 39.0～53.5 % by mole, Si amount is 18.0～31.5 % by mole, Al amount is 0.5～3.0 % by mole, Ti amount is 0～3.0 % by mole, Zn amount is 0～12.5 % by mole, Zr amount is 0 % by mole, Sn amount is 0.5～20.0 % by mole, Pb/Si than be 1.24～2.78 scope time obtained good result.That is the good result that, when Sn amount is the scope of 0.5～20.0 % by mole, obtained FF value and be 75～78, Eff is 17.0～17.8%.Particularly Pb amount is that 50.0 % by mole, B amount are that 6.0 % by mole, Si amount are that 25.0 % by mole, Al amount are that 3.0 % by mole, Li amount are that 3.0 % by mole, Zn amount are that 5.5～8.5 % by mole, P amount are that 2.0 % by mole, Sn amount are that 2.0～5.0 % by mole, S amount are the No.24,25 of 0.5 % by mole, the extremely result of excellence that obtained FF value and be 78, Eff is 17.7～17.8%.On the other hand, when Sn amount is 0.1 % by mole, FF value is 74～75, Eff is 16.7～16.9%, at Sn, measure while being 25.0 % by mole that FF value is 72, Eff is 16.3%, is all inadequate results.

In addition, comparative example No.28, 31～33 and comparative example No.30, in Pb amount, it is 50.0 % by mole, B amount is 6.0 % by mole, Si amount is 9.0～21.0 % by mole, Al amount is 3.0 % by mole, Li amount is 3.0 % by mole, Ti amount is 0 % by mole, Zn amount is 0～4.0 % by mole, Zr amount is 0 % by mole, P amount is 0～2.0 % by mole, Bi amount is 0～17.0 % by mole, Na amount is 0 % by mole, Sn amount is 5.0～20.0 % by mole, S amount is 0 % by mole, Ag amount is 0 % by mole, Pb/Si is than being in composition in 2.38～5.56 scope, in Si amount, it is 11.0～21.0 % by mole, Bi amount is 0～15.0 % by mole, Pb/Si than be 2.38～4.55 scope time obtained good result.That is the good result that, when Bi amount is the scope of 0～15.0 % by mole, obtained FF value and be 75～77, Eff is 17.0～17.4%.On the other hand, when being 17.0 % by mole, Bi amount is the inadequate result that FF value is 71, Eff is 15.8%.

In addition, embodiment No.34～42, being the example utilizing containing the investigation optimal conditions such as composition of Ti, is that 49.0～55.0 % by mole, B amount are that 6.0 % by mole, Si amount are that 20.0～30.0 % by mole, Al amount are that 3.0～6.0 % by mole, Li amount are that 3.0 % by mole, Ti amount are that 0～3.0 % by mole, Zn amount are that 0～6.5 % by mole, P amount are that 1.0～2.0 % by mole, Bi amount are 0～12.0 % by mole, Na in Pb amount ₂o amount is that 0～0.5 % by mole, Sn amount are that 1.0～5.0 % by mole, S amount are 0～0.5 % by mole, Ag amount while being the scope of 0～2.0 % by mole, the good result that obtained FF value and be 75～79, Eff is 17.0～17.9%.Particularly at Pb, measuring is 49.0～51.0 % by mole, Si measures is 24.0～26.0 % by mole, Al measures is 3.0 % by mole, Ti measures is 3.0 % by mole, Zn measures is 5.5～6.5 % by mole, P measures is 2.0 % by mole, Bi measures is 0 % by mole, Na ₂o amount is that 0 % by mole, Sn amount are that 2.0 % by mole, S amount are 0～0.5 % by mole, Ag amount while being the scope of 0 % by mole, the excellent result that obtained FF value and be 78～79, Eff is 17.7～17.9%.

In addition, the good result that as shown in embodiment No.51～52, even if P amount is the scope of 4.0～6.0 % by mole, also obtained FF value and be 75, Eff is 17.0%.

In addition, embodiment No.53～63, being that composition is carried out to the example that the upper limit etc. of Ti amount, Na amount, S amount is discussed in various changes, is that 35.6～54.8 % by mole, B amount are that 2.8～12.0 % by mole, Si amount are that 23.5～35.4 % by mole, Al amount are that 0～6.0 % by mole, Li amount are that 6.0～9.0 % by mole, Ti amount are that 0～6.0 % by mole, Zn amount are that 0～12.0 % by mole, Zr amount are that 0～0.5 % by mole, P amount are that 0～2.0 % by mole, Bi amount are 0～3.0 % by mole, Na in Pb amount ₂o amount is that 0～1.0 % by mole, Sn amount are 1.0～7.5 % by mole, S amount while being the scope of 0～2.0 % by mole, the good result that obtained FF value and be 75～79, Eff is 17.0～17.9%.Particularly at Pb, measuring is 44.0～53.0 % by mole, Si measures is 5.0～6.0 % by mole, Al measures is 0～3.0 % by mole, Li measures is 6.0 % by mole, Ti measures is 0 % by mole, Zn measures is 0～3.0 % by mole, Zr measures is 0 % by mole, P measures is 1.0～2.0 % by mole, Bi measures is 0～3.0 % by mole, Na ₂o amount is that 0～0.5 % by mole, Sn amount are 2.0 % by mole, S amount while being the scope of 0～0.5 % by mole, the excellent result that obtained FF value and be 78～79, Eff is 17.7～17.9%.

In addition, embodiment No.70～79, be that composition is carried out to the example that optimum condition is discussed in various changes, at Pb, measuring is 30.0～44.0 % by mole, B measures is 3.5～8.0 % by mole, Si measures is 25.0～36.0 % by mole, Al measures is 0～7.0 % by mole, Li measures is 12.0 % by mole, Ti measures is 0～3.0 % by mole, Zn measures is 0～11.0 % by mole, P measures is 0～2.0 % by mole, Bi measures is 0～2.0 % by mole, Na ₂o amount is that 0～1.0 % by mole, Sn amount are that 1.0～10.0 % by mole, S amount are 0～0.5 % by mole, Ag amount while being the scope of 0～0.5 % by mole, the extremely good result that obtained FF value and be 76～79, Eff is 17.3～17.9%.Particularly at Pb, measuring is 35.0～41.0 % by mole, B measures is 6.0～8.0 % by mole, Si measures is 27.0～32.0 % by mole, Al measures is 3.0～6.0 % by mole, Li measures is 12.0 % by mole, Ti measures is 3.0 % by mole, Zn measures is 3.0～4.0 % by mole, P measures is 0～2.0 % by mole, Bi measures is 0～1.0 % by mole, Na ₂o amount is that 0 % by mole, Sn amount are that 1.0～5.0 % by mole, S amount are 0 % by mole, Ag amount while being the scope of 0 % by mole, the excellent result that obtained FF value and be 78～79, Eff is 17.5～17.9%.

In addition, embodiment No.80,81, comparative example No.82, it is the upper limit example of investigation Li amount, in Pb amount, be that 38.0 % by mole, B amount are that 4.0 % by mole, Si amount are that 32.0～35.0 % by mole, Al amount are that 3.0 % by mole, Li amount are that 15.0～18.0 % by mole, P amount are that 0～2.0 % by mole, Sn amount are that 2.0～5.0 % by mole, S amount are that 0～0.5 % by mole, Ag amount are in the composition of 0～0.5 % by mole, the good result that obtained FF value and be 75～78, Eff is 17.0～17.7%.On the other hand, the inadequate result that when being that 36.0 % by mole, B amount are that 4.0 % by mole, Si amount are that 29.0 % by mole, Al amount are that 7.0 % by mole, Li amount are 21.0 % by mole, Sn amount while being the composition of 2.0 % by mole for Pb amount, become FF value and be 72, Eff is 16.1%.

In addition, embodiment No.83～92nd, in containing Bi system, the main Pb of change amount and Li measure to discuss the best example forming, in Pb amount, it is 36.0～58.0 % by mole, B amount is 3.0～7.0 % by mole, Si amount is 26.1～32.0 % by mole, Al amount is 3.0～6.0 % by mole, Li amount is 1.0～12.0 % by mole, Ti amount is 0～3.0 % by mole, Zn amount is 0～9.0 % by mole, Zr amount is 0 % by mole, P amount is 0～2.0 % by mole, Bi amount is 1.0～6.0 % by mole, Na amount is 0～0.5 % by mole, Sn amount is 0.5～5.0 % by mole, S amount is 0～0.5 % by mole, when Ag amount is the scope of 0 % by mole, having obtained FF value is 76～79, Eff is 17.1～17.9% good result.For Pb amount, be particularly more than 37.0 % by mole, B amount is below 6.0 % by mole, when Sn amount is the composition below 2.0 % by mole, it is more than 77 having obtained FF value, Eff is more than 17.4% better result, in addition, for Pb amount, be more than 37.0 % by mole, B amount is below 6.0 % by mole, Bi amount is below 3.0 % by mole, when Sn amount is the composition below 2.0 % by mole, it is more than 78 having obtained FF value, Eff is more than 17.6% more excellent characteristic, for Pb amount, be more than 37.0 % by mole, B amount is below 6.0 % by mole, Li amount is more than 3.0 % by mole, Bi amount is below 3.0 % by mole, when Sn amount is the composition below 2.0 % by mole, having obtained FF value is 79, Eff is more than 17.8% extremely excellent characteristic.

According to these evaluation results, in having used the electrode paste of the lead glass that contains Li, also have with the balanced of other elements and take into account, but be estimated as preferably: Pb amount is 24.0～64.0 % by mole, B amount is 1.0～18.0 % by mole, Si amount is 11.0～40.0 % by mole, Al amount is below 9.0 % by mole, Li amount is 1.0～18.0 % by mole, Ti amount is below 6.0 % by mole, Zn amount is below 15.0 % by mole, Zr amount is below 0.5 % by mole, P amount is below 6.0 % by mole, Bi amount is below 15.0 % by mole, Na amount is below 1.0 % by mole, Sn amount is 0.5～20.0 % by mole, S amount is below 2.0 % by mole, Ag amount is below 2.0 % by mole, Pb/Si is 0.6～4.6 scope.

In addition, according to the embodiment that has obtained good especially result, more preferably Pb amount is 30.0～61.0 % by mole, B amount is 2.8～12.0 % by mole, Si amount is 20.0～36.0 % by mole, Al amount is below 7.0 % by mole, Li amount is 1.0～15.0 % by mole, Ti amount is below 3.0 % by mole, Zn amount is below 12.0 % by mole, Zr amount is 0 % by mole, P amount is below 2.0 % by mole, Bi amount is below 12.0 % by mole, Na amount is below 0.5 % by mole, Sn amount is 0.5～10.0 % by mole, S amount is below 0.5 % by mole, Ag amount is below 0.5 % by mole, Pb/Si is 1.0～2.5 scope.In addition, can say that the amount of Pb is particularly preferably that 35.0～59.5 % by mole, B amount are that 4.0～8.0 % by mole, Si amount are that 24.0～32.0 % by mole, Al amount are that 6.0 % by mole of following, Zn amounts are that 8.5 % by mole of following, Bi amounts are that 3.0 % by mole of following, Sn amounts are the scope that 1.0～5.0 % by mole, Pb/Si are 1.1～2.1.

In addition, in above-mentioned experimental data, when for not containing Li be, when all containing the composition of Al in the arbitrary system that is of Li, have electric leakage rheology many, but the tendency that FF value uprises, it is large that firing range also becomes.Yet when Al is too much, open circuit voltage significantly reduces.

In addition, although the tendency that has FF value to uprise when the composition for containing Ti, when Ti is too much, the tendency that exists contact resistance to uprise.

In addition, no matter can confirm the tendency that B is excessive or very few open circuit voltage all reduces.Therefore the tendency that, all has in any case FF value to reduce.

, in each above-mentioned embodiment, although used respectively a kind of glass when modulator electrode is stuck with paste, also can mix 2 kinds of glass, be that erosion glass and the high alms giver's glass of donor concentration of low softening point is used.No.93～102nd shown in following table 5, the composition example of alms giver's glass, in the present embodiment, by Pb amount, it is 28.0～44.0 % by mole, B amount is 3.0～9.0 % by mole, Si amount is 24.1～32.0 % by mole, Al amount is 0.5～6.0 % by mole, Li amount is 10.0～18.0 % by mole, Ti amount is 0～6.0 % by mole, Zn amount is 0～10.0 % by mole, Zr amount is 0～0.5 % by mole, P amount is 4.0～9.0 % by mole, Bi amount is 0～1.0 % by mole, Na amount is 0～0.5 % by mole, Sn amount is 0～1.0 % by mole, S amount is 0～1.5 % by mole, Pb/Si is used as alms giver's glass than the glass that is 0.88～1.56 scope.Above-mentioned P ₂o ₅as the alms giver's supply source for silicon substrate 20, many amounts have been added.Use separately that FF value in the situation of this alms giver's glass is 50～73, Iv is for below 0.1A.

Table 5 forms (mol%)

Alms giver's glass shown in above-mentioned table 5, mixes use to reach the mode of ratio and the glass (corroding glass) of each embodiment shown in above-mentioned table 1～4 of 10～30 % by weight of total glass amount.For example, in above-mentioned paste allotment standard, among frit 4 % by weight, erosion glass is made as 3.6 % by weight, alms giver's glass is made as 0.4 % by weight.Now, select alms giver's glass and than softening point, exceed the combination of the scope of 50～200 ℃ so that become it with erosion glassy phase.For example, the erosion glass slow with respect to erosive velocity, the alms giver's glass that be preferably used as alms giver's phosphorus more, softening point is high.

In above-mentioned hybrid glass is, corrode the glass that glass can be used the embodiment arbitrarily in table 1～4, alms giver's glass can be used the glass arbitrarily of table 5, but specifically, for example can enumerate alms giver's glass No.94, with any combination of corroding among glass No.18,83,84,37.When utilization has used the electrode paste of these hybrid glass to form above-mentioned sensitive surface electrode 20, even if any combination can both obtain FF value and be more than 79, Eff is more than 17.9% extremely excellent result.Particularly the preferably combination of alms giver's glass No.94 and erosion glass No.83, because electric current increases, is more than 18% result so obtain Eff.

In addition, even use glass a little less than aggressivity, be that the glass that FF value is little also can access good result as alms giver's glass.For example can enumerate alms giver's glass No.100 and any combination of corroding in glass No.24,36.Even these combinations, also similarly obtain with the situation of having used alms giver's glass No.94 that FF value is more than 79, Eff is more than 17.9% excellent result.

With reference to accompanying drawing, the present invention is had been described in detail above, but the present invention can also implement in other mode various changes in addition in the scope that does not depart from its purport.

Claims

1. an electrode of solar battery paste composite, it comprises electroconductive powder, frit and vehicle, it is characterized in that,

Described frit contains lead glass, and described lead glass converts and to contain Sn with the scope of 0.5～20.0 % by mole by oxide.

2. electrode of solar battery paste composite according to claim 1, described lead glass is to convert and contain Sn, with the scope of 0.6～18 % by mole, contain Li with the scope of 0.5～20.0 % by mole by oxide ₂o, with the scopes of 24～64 % by mole, contain PbO, with the scope of 1～18 % by mole, contain B ₂o ₃, with the scope of 11～40 % by mole, contain SiO ₂, with the scope of 0～6.0 % by mole, contain P ₂o ₅lead glass.

3. electrode of solar battery paste composite according to claim 1, described lead glass is to convert and contain Sn, with the scopes of 55～65 % by mole, contain PbO, with the scope of 1～8 % by mole, contain B with the scope of 0.5～12.0 % by mole by oxide ₂o ₃, with the scope of 21～36 % by mole, contain SiO ₂, with the scope of 0～4.0 % by mole, contain P ₂o ₅, and containing Li ₂the lead glass of O.