KR20110014676A - Conductors for photovoltaic cells: compositions containing submicron particles - Google Patents

Abstract

Embodiments of the present invention relate to silicon semiconductor devices and conductive thick film compositions for use in solar cell devices.

Description

Photoconductor: Composition containing submicron particles {CONDUCTORS FOR PHOTOVOLTAIC CELLS: COMPOSITIONS CONTAINING SUBMICRON PARTICLES}

Embodiments of the present invention relate to silicon semiconductor devices and conductive thick film compositions for use in solar cell devices.

Conventional solar cell structures having a p-type base may have a negative electrode that may be on the front side of the cell (also called the sun-side or illuminated side) and a positive electrode that may be on the opposite side. Has Appropriate wavelengths of radiation falling into the p-n junction of the semiconductor body serve as an external energy source for generating hole-electron pairs in the body. Due to the potential difference present in the p-n junction, holes and electrons move across the junction in opposite directions, thereby creating a current flow that can deliver power to the external circuit. Most solar cells are in the form of silicon wafers that are metallized, ie, have metal contacts that are electrically conductive.

Demand for compositions, structures (eg, semiconductors, solar cells, or photodiode structures), and semiconductor devices (eg, semiconductors, solar cells, or photodiode devices) with improved electrical performance, and methods of making the same There is.

Embodiments of the invention include: (a) one or more conductive materials; (b) one or more inorganic binders; And (c) an organic vehicle, wherein 1-15% of the inorganic component is submicron particles. In one embodiment, 85-99% of the inorganic component may have a d50 of 1.5-10 micrometers. In one embodiment, the one or more conductive materials can include silver. In one embodiment, the portion of silver contains submicron particles. In one embodiment, the submicron particles have a d50 of 0.1 to 1 micrometer. In one embodiment, the submicron particles have a d50 of 0.1 to 0.6 micrometers. In one embodiment, the particles have a bimodal size distribution.

The composition comprises: (a) a metal selected from Zn, Pb, Bi, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Cu, and Cr; (b) metal oxides of one or more metals selected from Zn, Pb, Bi, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Cu, and Cr; (c) any compound capable of producing the metal oxide of (b) upon firing; And (d) one or more additives selected from the group consisting of mixtures thereof. In one embodiment, the additive may include ZnO, or a compound that forms ZnO upon firing. In one embodiment, the ZnO and / or inorganic binder may comprise submicron particles. ZnO may be 2 to 10 weight percent of the total composition. The glass frit may be 1 to 6 weight percent of the total composition. The conductive material may comprise Ag. Ag may be 90 to 99% by weight of solids in the composition. In one embodiment, the inorganic component may be 70 to 95 weight percent of the total composition.

Further embodiments include: (a) providing a semiconductor substrate, one or more insulating films, and a thick film composition described herein; (b) applying the insulating film to the semiconductor substrate; (c) applying a thick film composition to an insulating film on a semiconductor substrate, and (d) firing the semiconductor, insulating film, and thick film composition. In one aspect, the insulating film may comprise one or more components selected from: titanium oxide, silicon nitride, SiNx: H, silicon oxide and silicon oxide / titanium oxide.

Further embodiments relate to semiconductor devices made by the methods described herein. One aspect relates to a semiconductor device comprising an electrode comprising a composition described herein prior to firing. One embodiment relates to a solar cell comprising a semiconductor device.

One embodiment includes a semiconductor substrate, an insulating film, and a front electrode, wherein the front electrode comprises at least one component selected from the group consisting of zinc-silicate, willemite, and bismuth silicate. It is about.

<Figure 1>
1 is a process flowchart showing the manufacture of a semiconductor device.
Reference numerals shown in FIG. 1 are described below.
10: p-type silicon substrate
20: n-type diffusion layer
30: silicon nitride film, titanium oxide film, or silicon oxide film
40: p + layer (rear field, BSF)
60: aluminum paste formed on the back side
61: aluminum back electrode (obtained by firing rear aluminum paste)
70: silver or silver / aluminum paste formed on the back side
71: silver or silver / aluminum back electrode (obtained by firing back silver paste)
500: silver paste formed on the front surface according to the present invention
501: Silver front electrode according to the present invention (formed by firing front silver paste)

There is a need for improved solar cells with increased efficiency. There is a need for conductive compositions suitable for the formation of narrow conductor lines with increased height. Aspects of the present invention relate to compositions containing submicron particles. The composition may be a thick film composition. Such compositions can be used to form solar cell electrodes. The electrode can be on the front side of the solar cell. In one embodiment, the electrode lines can be narrow and can have increased height.

As used herein, "thick film composition" refers to a composition having a thickness of 1 to 100 microns upon firing on a substrate. The thick film composition may contain a conductive material, a glass composition, and an organic vehicle. The thick film composition may comprise additional components. As used herein, additional ingredients are referred to as "additives".

The compositions described herein comprise one or more electrically functional materials and one or more glass frits dispersed in an organic medium. Such a composition may be a thick film composition. The composition may also include one or more additive (s). Exemplary additives may include metals, metal oxides, or any compound capable of producing such metal oxides during firing.

In one embodiment, the electrically functional powder may be a conductive powder. In one embodiment, composition (s), such as conductive compositions, may be used in the semiconductor device. In an aspect of this embodiment, the semiconductor device may be a solar cell or a photodiode. In a further aspect of this embodiment, the semiconductor device can be one of a wide variety of semiconductor devices. In one embodiment, the semiconductor device can be a solar cell.

In one embodiment, the thick film compositions described herein can be used in solar cells. In aspects of this embodiment, the solar cell efficiency may be greater than 70% of the reference solar cell. In further embodiments, the solar cell efficiency may be greater than 80% of the reference solar cell. Solar cell efficiency may be greater than 90% of a reference solar cell.

In one embodiment, the ratio of the organic medium in the thick film composition to the inorganic component in the dispersion may depend on the type of organic medium used and the method of application of the paste, as determined by one skilled in the art. In one embodiment, the dispersion may comprise from 5 to 30% by weight of organic medium (vehicle) and from 70 to 95% by weight of inorganic components to obtain good wetting.

In one embodiment, the portion of the inorganic component may be submicron particles. In an aspect of this embodiment, the submicron particles can have a d50 of 0.1 to 1 micrometer. In a further aspect, the submicron particles can have a d50 of 0.1 to 0.8 micrometers. In a further aspect, the submicron particles can have a d50 of 0.2 to 0.6 micrometers.

In one embodiment, the submicron particles can be 1-15% by weight of the composition. In further embodiments, the submicron particles can be 2 to 10 weight percent of the composition. In further embodiments, the submicron particles can be 3 to 6 weight percent of the composition.

In one embodiment, the submicron particles can comprise a portion of the conductive material. In one aspect, 1-15% by weight of the conductive material may be submicron particles. In a further aspect, 2 to 10% by weight of the conductive material may be submicron particles. In further aspects, 3 to 6 weight percent of the conductive composition may be submicron particles.

In one embodiment, a portion of the composition may have a d50 of 1.5 to 10 micrometers. In an aspect of this embodiment, 85 to 99% by weight of the inorganic component of the composition may have a d50 of 1.5 to 10 microns. In an aspect of this embodiment, a portion of the composition may have a d50 of 2.0 to 7.0 micrometers. In an aspect of this embodiment, a portion of the composition may have a d50 of 2.5 to 5.0 micrometers.

In further aspects, the conductive material may comprise silver. In one aspect, 50-100% by weight of the conductive material may be silver. In a further aspect, 70-99%, 70-98%, or 80-95% by weight of the conductive material may be silver.

Glass frit

In an aspect of the present invention, the composition comprises a glass frit composition. Glass frit compositions useful in the present invention will be readily appreciated by those skilled in the art. For example, glass frit compositions useful in the compositions used to make the front side solar cell electrodes can be used. Exemplary glass frit compositions include lead borosilicate glass. In one embodiment, glass frit compositions useful in the present invention comprise 20 to 24 weight percent SiO ₂ , 0.2 to 0.8 weight percent Al ₂ O ₃ , 40 to 60 weight percent PbO, and 5 to 8 weight percent B ₂ O ₃ may include. In one embodiment, the glass frit composition may also optionally include 3-7 wt.% TiO ₂ . In one embodiment, the glass frit composition may also optionally include one or more fluorine-containing components, including but not limited to: salts of fluorine, fluorides, metal oxyfluoride compounds, and the like. Such fluorine-containing components include, but are not limited to, PbF ₂ , BiF ₃ , AlF ₃ , NaF, LiF, KF, CsF, ZrF ₄ , TiF ₄ and / or ZnF ₂ . In one embodiment, the glass frit composition may comprise 8 to 13 weight percent PbF ₂ .

In a further aspect of this embodiment, the thick film composition may comprise an electrically functional powder and a glass-ceramic frit dispersed in an organic medium. In one embodiment, such thick film conductor composition (s) can be used in semiconductor devices. In an aspect of this embodiment, the semiconductor device may be a solar cell or a photodiode.

Conductive material

In one embodiment, the thick film composition may comprise a functional phase that imparts appropriate electrical functional properties to the composition. In one embodiment, the electrically functional powder may be a conductive powder. In one embodiment, the electrically functional phase may comprise a conductive material (also referred to herein as conductive particles). The conductive particles can include, for example, conductive powder, conductive flakes, or mixtures thereof.

In one embodiment, the conductive particles may comprise Ag. In further embodiments, the conductive particles may comprise silver (Ag) and aluminum (Al). In further embodiments, the conductive particles can include, for example, one or more of the following: Cu, Au, Ag, Pd, Pt, Al, Ag-Pd, Pt-Au, and the like. In one embodiment, the conductive particles may comprise one or more of the following: (1) Al, Cu, Au, Ag, Pd and Pt; (2) alloys of Al, Cu, Au, Ag, Pd and Pt; And (3) mixtures thereof.

In one embodiment, the functional phase of the composition may include coated or uncoated silver particles that are electrically conductive. In embodiments in which silver particles are coated, the silver particles are at least partially coated with a surfactant. In one embodiment, the surfactant may comprise one or more of the following non-limiting surfactants: stearic acid, palmitic acid, salts of stearate, salts of palmitate, lauric acid, palmitic acid, oleic acid , Stearic acid, capric acid, myristic acid and linoleic acid, and mixtures thereof. Counter ions may be, but are not limited to, hydrogen, ammonium, sodium, potassium and mixtures thereof.

In one embodiment, silver may be 60-90% by weight of the paste composition. In further embodiments, silver may be 70-85% by weight of the paste composition. In further embodiments, silver may be 75 to 85 weight percent of the paste composition. In further embodiments, silver may be 78 to 82 weight percent of the paste composition.

In one embodiment, silver may be 90-99% by weight of solids (ie, excluding organic vehicle) in the composition. In further embodiments, silver may be 92-97 wt% of the solids in the composition. In further embodiments, silver may be 93 to 95 weight percent of solids in the composition.

As used herein, "particle size" is intended to mean "average particle size" and "average particle size" means 50% volume distribution size. The volume distribution size can be determined by a number of methods understood by one of ordinary skill in the art, including but not limited to LASER diffraction and dispersion methods using a Microtrac particle size analyzer.

In one embodiment, the portion of the conductive material may be submicron particles. In an aspect of this embodiment, the submicron particles can have a d50 of 0.1 to 1 micrometer. In a further aspect, the submicron particles can have a d50 of 0.1 to 0.8 micrometers. In a further aspect, the submicron particles can have a d50 of 0.2 to 0.6 micrometers.

In one embodiment, 1-15% by weight of the conductive material may be submicron particles. In a further aspect, 2 to 10% by weight of the conductive material may be submicron particles. In further aspects, 3 to 6 weight percent of the conductive composition may be submicron particles.

In one embodiment, the portion of the conductive material may have a d50 of 1.5 to 10 micrometers. In an aspect of this embodiment, 85 to 99% by weight of the conductive material may have a d50 of 1.5 to 10 microns. In an aspect of this embodiment, the portion of the conductive material may have a d50 of 2.0 to 7.0 micrometers. In an aspect of this embodiment, the portion of the conductive material may have a d50 of 2.5 to 5.0 micrometers.

additive

In one embodiment, the thick film composition may comprise one or more additives. In one embodiment, the additive may be selected from one or more of the following: (a) metals selected from Zn, Pb, Bi, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Cu and Cr ; (b) metal oxides of at least one metal selected from Zn, Pb, Bi, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Cu and Cr; (c) any compound capable of producing the metal oxide of (b) upon firing; And (d) mixtures thereof.

In one embodiment, the additive may include a Zn-containing additive. The Zn-containing additive may comprise one or more of the following: (a) Zn, (b) metal oxide of Zn, (c) any compound capable of producing metal oxide of Zn upon firing, and (d) Its mixture. In one embodiment, the Zn-containing additive may comprise Zn resinate.

In one embodiment, the Zn-containing additive may comprise ZnO. In one embodiment, the portion of ZnO may comprise submicron particles.

In one embodiment, ZnO may be present in the composition in the range of 2-10% by weight of the total composition. In one embodiment, ZnO may be present in the range of 3 to 7 weight percent of the total composition. In further embodiments, ZnO may be present in the range of 4 to 6 weight percent of the total composition.

Organic medium

In one embodiment, the thick film compositions described herein may comprise an organic medium. The inorganic component can be mixed with the organic medium, for example by mechanical mixing, to form a paste. A wide variety of inert viscous materials can be used as the organic medium. In one embodiment, the organic medium can be one that has a sufficient degree of stability and can disperse the inorganic components. In one embodiment, the rheological properties of the medium include certain applications including stable dispersion of solids, adequate viscosity and thixotropy for screen printing, adequate wettability of substrate and paste solids, good drying speed, and good plasticity properties. Properties can be imparted to the composition. In one embodiment, the organic vehicle used in the thick film composition may be a non-aqueous inert liquid. The use of any of a variety of organic vehicles, which may or may not contain thickeners, stabilizers and / or other conventional additives, is contemplated. The organic medium may be a solution of polymer (s) in solvent (s). In one embodiment, the organic medium may also include one or more components such as surfactants. In one embodiment, the polymer may be ethyl cellulose. Other exemplary polymers include ethylhydroxyethyl cellulose, wood rosin, mixtures of ethyl cellulose and phenolic resins, polymethacrylates of lower alcohols, and monobutyl ethers of ethylene glycol monoacetate, or mixtures thereof. In one embodiment, solvents useful in the thick film compositions described herein include ester alcohols and terpenes such as alpha- or beta-terpinol, or other solvents such as kerosene, dibutylphthalate, butyl carbitol , Butyl carbitol acetate, hexylene glycol and mixtures of high boiling alcohols and alcohol esters. In further embodiments, the organic medium may comprise a volatile liquid to promote rapid curing after being applied on the substrate.

In one embodiment, the polymer may be present in the organic medium, for example, in the range of 8% to 11% by weight of the total composition. The thick film silver composition can be adjusted to the desired screen printable viscosity using an organic medium.

Calcined Thick Film Composition

In one embodiment, the organic medium may be removed during drying and firing of the semiconductor device. In one aspect, the glass frit, Ag, and additives may be sintered during firing to form the electrode. The fired electrode may include components, compositions, and the like, resulting from the firing and sintering processes.

In an aspect of this embodiment, the semiconductor device may be a solar cell or a photodiode.

Manufacturing Method of Semiconductor Device

One embodiment relates to a method for manufacturing a semiconductor device. In one embodiment, semiconductor devices can be used in solar cell devices. The semiconductor device may comprise a front electrode, and prior to firing, the front (irradiation surface) electrode may comprise the composition (s) described herein.

In one embodiment, a method of manufacturing a semiconductor device comprises: (a) providing a semiconductor substrate; (b) applying the insulating film to the semiconductor substrate; (c) applying the composition described herein to an insulating film; And (d) firing the device.

Exemplary semiconductor substrates useful in the methods and devices described herein are recognized by those skilled in the art: including but not limited to single crystal silicon, polycrystalline silicon, ribbon silicon, and the like. The semiconductor substrate may have a junction. The semiconductor substrate may be doped with phosphorus and boron to form a p / n junction. Methods of doping a semiconductor substrate are understood by those skilled in the art.

The semiconductor substrate can vary in size (length x width) and thickness as will be appreciated by those skilled in the art. In a non-limiting example, the thickness of the semiconductor substrate can range from 50 to 500 micrometers; 100 to 300 micrometers; Or 140 to 200 micrometers. In a non-limiting example, the length and width of the semiconductor substrate are both equally 100 to 250 mm; 125 to 200 mm; Or 125 to 156 mm.

Exemplary insulating films useful in the methods and devices described herein are recognized by those skilled in the art: silicon nitride, silicon oxide, titanium oxide, SiN _x : H, hydrogenated amorphous silicon nitride, and silicon oxide / titanium oxide films. The insulating film can be formed by PECVD, CVD, and / or other techniques known to those skilled in the art. In the embodiment where the insulating film is silicon nitride, the silicon nitride film may be formed by plasma chemical vapor deposition (PECVD), thermal CVD process, or physical vapor deposition (PVD). In the embodiment where the insulating film is silicon oxide, the silicon oxide film may be formed by thermal oxidation, thermal CVD, plasma CVD, or PVD. The insulating film (or layer) may also be called an antireflective coating (ARC).

The compositions described herein are ARC-coated semiconductors by various methods known to those skilled in the art, including but not limited to screen printing, inkjet, coextrusion, syringe dispense, direct writing, and aerosol inkjet. It can be applied to a substrate. In one embodiment, the composition can be applied to a substrate using the methods and apparatus described in US Patent Publication No. 2003/0100824, which is incorporated herein by reference. The composition can be applied in a pattern. The composition can be applied in any shape and at any location. In one embodiment, the composition can be used to form both conductive fingers and busbars of the front electrode. In one embodiment, the line width of the conductive finger is between 10 and 200 micrometers; 40 to 150 micrometers; Or 60 to 100 micrometers. In one embodiment, the line width of the conductive finger is between 10 and 100 micrometers; 15 to 80 micrometers; Or 20 to 75 micrometers. In one embodiment, the line thickness of the conductive finger is between 5 and 50 micrometers; 10 to 35 micrometers; Or 15 to 30 micrometers. In further embodiments, the composition can be used to form conductive, Si contact fingers.

The composition coated on the ARC-coated semiconductor substrate can be dried, for example, for 0.5 to 10 minutes and then calcined, as will be appreciated by those skilled in the art. In one embodiment, volatile solvents and organics can be removed during the drying process. Firing conditions will be recognized by those skilled in the art. In an exemplary, non-limiting firing condition, the silicon wafer substrate is heated to a maximum temperature of 600-900 ° C. for a duration of 1 second to 2 minutes. In one embodiment, the maximum silicon wafer temperature reached during firing is in the range of 650-800 ° C. for a duration of 1-10 seconds. In a further embodiment, the electrode formed from the conductive thick film composition (s) can be fired in an atmosphere consisting of a mixed gas of oxygen and nitrogen. This firing process removes the organic medium and sinters the Ag powder and the glass frit in the conductive thick film composition. In further embodiments, the electrodes formed from the conductive thick film composition (s) may be fired above the organic medium removal temperature in an inert atmosphere containing no oxygen. This firing process sinters or melts the base metal conductive material, such as copper, in the thick film composition.

In one embodiment, during firing, the electrode (preferably a finger) to be fired can react with and penetrate the insulating film to form an electrical contact with the silicon substrate.

In further embodiments, prior to firing, other conductive materials and device enhancement materials are applied to the opposite type region of the semiconductor device and co-fired or sequentially fired with the compositions described herein. The opposite type region of the device is on the opposite side of the device. The material serves as an electrical contact, a passivating layer, and a solderable tabbing area.

In one embodiment, the opposite type region may be on the non-illuminated side (rear) of the device. In an aspect of this embodiment, the backside conductive material may contain aluminum. Exemplary backside aluminum-containing compositions and methods of application are described, for example, in US Patent Application Publication 2006/0272700, which is incorporated herein by reference.

In a further aspect, the solderable tabbing material may contain aluminum and silver. Exemplary tabbing compositions containing aluminum and silver are described, for example, in US Patent Publication No. 2006/0231803, which is incorporated herein by reference.

In further embodiments, the materials applied to the opposite type regions of the device are adjacent to the materials described herein because the p and n regions are formed side by side. Such devices place all metal contact materials on the non-irradiated surface (back side) of the device to maximize incident light onto the irradiated surface (front side).

The semiconductor element can be manufactured by the following method from a structural element consisting of a semiconductor substrate having a junction and a silicon nitride insulating film formed on its main surface. A method of manufacturing a semiconductor device includes applying (eg, coating and printing) a conductive thick film composition having the ability to penetrate the insulating film on a insulating film, in a predetermined shape and at a predetermined position, and then conducting a conductive thick film. Baking the composition to melt and penetrate the insulating film, and achieving electrical contact with the silicon substrate. The electrically conductive thick film composition, as described herein, comprises a silver powder, a Zn-containing additive, and a glass or glass powder mixture having a softening point of 300 to 600 ° C., optionally as an additional metal / metal oxide, dispersed in an organic vehicle. Thick film paste composition prepared with additive (s).

One embodiment of the present invention relates to a semiconductor device manufactured by the method described herein. Devices containing the compositions described herein may contain zinc-silicates, as described above.

One embodiment of the present invention relates to a semiconductor device manufactured by the method described above.

Additional substrates, devices, manufacturing methods, and the like that can be used with the thick film compositions described herein are described in US Patent Application Publication Nos. 2006/0231801, 2006/0231804, and 2006/0231800, which are described herein. It is incorporated by reference in its entirety.

[Example]

The organic medium was prepared by dissolving the polymer in an organic solvent at about 100 ° C. To the organic medium, other ingredients were added, including silver powder, glass frit, zinc oxide and other additives. The resulting mixture was dispersed by a roll-mill process known in the thick film paste manufacturing industry. Compositions I, II, and III, shown in Table 1, were formed.

Pastes from Compositions I and II were filtered through a Roki 40L-SHP-200XS filter capsule prior to printing. Composition III was used without filtration.

Pastes were evaluated at room temperature using a 3D-450 Smart Pump ™ printer manufactured by nScrypt Inc, using a reusable ceramic pen tip of ID / OD 50/75 μm. The pump pressure was 108.9 to 100 psi (68.9 kPa to 689.5 kPa). The print speed was 200 mm per second to 300 mm per second. The gap between the pen tip and the substrate surface was 150 μm.

Groups of ten 10.2 cm (4 inch) long lines were printed, dried in a box oven at 150 ° C. for 20 minutes, and fired in a belt furnace at 850 ° C. peak temperature for 2 minutes.

TABLE I

A mixture of spherical and flake shapes having silver powder I, sizes D10 = 0.88, D50 = 4.60, D95 = 10.73 micrometers.

Silver powder II, spherical powder with size D10 = 1.0, D50 = 1.71, D95 = 4.41 micrometer and surface area of 0.44 m 2 / g.

Silver powder III, spherical powder with sizes D10 = 0.26, D50 = 0.45, D95 = 1.67 micrometers, and 99.5% solids. Surface area is 1.0 m2 / g.

Glass frit I, SiO ₂ 23.0%, Al ₂ O ₃ 0.4%, PbO 58.8% and B ₂ O ₃ , based on the weight percent of the glass composition, having sizes D10 = 0.36, D50 = 0.61 and D95 = 1.44 micrometers 7.8%.

Glass frit II, SiO ₂ 22.08%, Al ₂ O ₃ 0.38%, PbO 46.68%, B ₂ O ₃ , based on the weight percent of the glass composition, having sizes D10 = 0.42, D50 = 0.77 and D90 = 1.96 micrometers 6.79%, TiO ₂ 5.86% and PbF ₂ 10.72%.

Glass frit III, SiO ₂ 22.08%, Al ₂ O ₃ 0.38%, PbO 46.68%, B ₂ O ₃ , based on the weight percent of the glass composition, having dimensions D10 = 0.34, D50 = 0.50 and D95 = 0.89 micrometers 6.79%, TiO ₂ 5.86% and PbF ₂ 10.72%. Zinc oxide, purchased from Aldrich Chemicals.

Example I. Composition I could pass a 50/75 micron pen tip under a pump pressure of less than 50 psi (344.7 kPa) for a period of less than 5 minutes before the pen tip was clogged. The resulting fired lines were 83 micrometers wide and 13 micrometers high.

Example II. Composition I could pass a 75/125 micrometer pen tip under a pump pressure of less than 60 psi (413.7 kPa) for a period of less than 30 minutes before the pen tip was clogged. The best result fired lines were 100 micrometers wide and 12 micrometers high.

Example III. Composition II could pass through a 50/75 micron pen tip under a pump pressure in the range of 10 psi to 100 psi (68.9 kPa to 689.5 kPa) for a period of at least 30 minutes before printing was stopped. The resulting fired lines were 89 micrometers wide and 19 micrometers high.

Example IV. Blends of composition II and composition III, having a weight percentage ratio of 95.5 to 4.5, are 50/75 micrometers under a pump pressure ranging from 68.9 kPa to 551.6 kPa (10 psi to 80 psi) for a period of at least 3 hours before printing is stopped. I could go through the pen tip. The resulting fired lines were 67 micrometers wide and 25 micrometers high.

Example V. Composition III could not print through a 50/75 micron pen tip under a pump pressure of more than 30 psi. At 30 psi, printing continued for less than 5 seconds before the pen tip was clogged.

Example VI. Composition III could print through a 75/125 micrometer pen tip under a pump pressure greater than 60 psi. Under 60 psi, printing continued for less than 5 minutes before the pen tip was clogged.

Example VII. A series of blends of Composition II and Composition III were prepared and printed, having a ratio in the range of 90 to 10 to 10 to 90 by weight. Once composition III was greater than 30%, the 50/75 micron pen tip was clogged within 1 minute.

Example VIII. Analyze the efficiency of the printed substrate. Exemplary efficiency tests are provided below. The efficiency of the solar cells from Example IV is expected to be greater than the efficiency of the solar cells from other examples.

Test procedure-efficiency

Solar cells constructed according to the methods described herein are tested for conversion efficiency. An exemplary efficiency test method is provided below.

In one embodiment, a solar cell constructed according to the method described herein is placed in a commercial I-V tester (ST-1000) for efficiency measurement. Xen Arc lamps in I-V testers simulate sunlight at a known intensity and irradiate the front of the cell.

The tester uses the multipoint contact method to determine the I-V curve of the cell by measuring the current (I) and voltage (V) at approximately 400 load resistance settings. Both the fill factor (FF) and the efficiency (Eff) are calculated from the I-V curve.

Claims (15)

(a) providing a semiconductor substrate, at least one insulating film and a thick film composition; (b) applying an insulating film to the semiconductor substrate; (c) applying the thick film composition to the insulating film on the semiconductor substrate; And (d) firing the semiconductor, insulating film and thick film composition,
The thick film composition comprises (i) at least one conductive material, (ii) at least one inorganic binder, and (iii) an organic vehicle,
1-15% of the inorganic component is a submicron particle. (a) one or more conductive materials;
(b) one or more inorganic binders; And
(c) comprises an organic vehicle,
A semiconductor device comprising an electrode comprising, before firing, a composition wherein 1 to 15% of the inorganic component is submicron particles. The device of claim 2, wherein 85 to 99% of the inorganic components have a d 50 of 1.5 to 10 microns. The device of claim 2, wherein the at least one conductive material comprises silver. The device of claim 4, wherein the submicron particles comprise silver. The device of claim 2, wherein the submicron particles have a d50 of 0.1 to 1 micron. The device of claim 2, wherein the submicron particles have a d50 of 0.1 to 0.6 micrometers. The device of claim 2, wherein the inorganic component has a bimodal size distribution. The device of claim 2, wherein the thick film composition further comprises one or more additives. The method of claim 9, wherein the one or more additives comprise (a) a metal selected from Zn, Pb, Bi, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Cu and Cr; (b) metal oxides of at least one metal selected from Zn, Pb, Bi, Gd, Ce, Zr, Ti, Mn, Sn, Ru, Co, Fe, Cu and Cr; (c) any compound capable of producing the metal oxide of (b) upon firing; And (d) a component selected from the group consisting of mixtures thereof. The device of claim 10, wherein the one or more inorganic additives comprise ZnO. The device of claim 5, wherein the submicron particles further comprise ZnO and an inorganic binder. The device of claim 2, further comprising an insulating film and a semiconductor substrate. A solar cell comprising the semiconductor device of claim 2. The device of claim 13, wherein the insulating film comprises one or more components selected from titanium oxide, silicon nitride, SiN x: H, silicon oxide, and silicon oxide / titanium oxide.

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