POLY-SILOXANE CONTAINING ORGANIC VEHICLE FOR ELECTROCONDUCTIVE PASTES

• US 20170200837A1
• Filed: 03/24/2017
• Published: 07/13/2017
• Est. Priority Date: 09/25/2015
• Status: Active Grant

• Current Assignee: Heraeus Precious Metals North America Conshohocken LLC (Einhorn Verwaltungsgesellschaft mbH)
• Original Assignee: Heraeus Precious Metals North America Conshohocken LLC (Einhorn Verwaltungsgesellschaft mbH)
• Inventors: RASKAR, DEVIDAS, Yang, Yi, Song, Lixin, Zhai, Guang
• Granted Patent: US 10,217,876 B2
• Time in Patent Office: Days
• CPC Class Codes: C03C 8/18 containing free metals
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: H01B 1/16 the conductive material comprising metals or alloys
• CPC Class Codes: H01L 31/00 Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof H10K30/00 takes precedence; devices consisting of a plurality of solid state components formed in, or on, a common substrate, other than combinations of radiation-sensitive components with one or more electric light sources, H01L27/00
• CPC Class Codes: H01L 31/02167 for solar cells
• CPC Class Codes: H01L 31/02168 the coatings being antireflective or having enhancing optical properties for the solar cells
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/022483 composed of zinc oxide [ZnO]
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/068 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
• CPC Class Codes: H01L 31/1864 Annealing
• CPC Class Codes: H01L 31/1884 Manufacture of transparent electrodes, e.g. TCO, ITO
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

The invention relates to a passivated emitter rear solar cell, comprising a silicon substrate having a front and back surface, a rear passivation layer on the back surface of the silicon substrate having a plurality of open holes formed therein, an aluminum back contact layer formed in the open holes of the rear passivation layer, and at least one backside soldering tab on the back surface of the silicon substrate. The backside soldering tab is formed from an electroconductive paste composition comprising conductive metallic particles, at least one lead-free glass frit, and an organic vehicle comprising at least one silicone oil.

Claims

1. A passivated emitter rear solar cell, comprising:

a silicon substrate having a front and back surface;

a rear passivation layer on the back surface of the silicon substrate having a plurality of open holes formed therein;

an aluminum back contact layer formed in the open holes of the rear passivation layer; and

at least one backside soldering tab on the back surface of the silicon substrate,

wherein the backside soldering tab is formed from an electroconductive paste composition comprising conductive metallic particles, at least one lead-free glass frit, and an organic vehicle comprising at least one silicone oil.

2. The passivated emitter rear solar cell of claim 1, wherein the rear passivation layer comprises alumina.

3. The passivated emitter rear solar cell of claim 1, further comprising a rear capping layer formed between the rear passivation layer and the aluminum back contact layer.

4. The passivated emitter rear solar cell of claim 3, wherein the rear capping layer comprises silicon nitride.

5. The passivated emitter rear solar cell of claim 1, wherein the conductive metallic particles are present in the electroconductive paste composition in an amount of less than about 70 wt %, based upon 100% total weight of the paste.

6. The passivated emitter rear solar cell of claim 1, wherein the conductive metallic particles are silver particles.

7. The passivated emitter rear solar cell of claim 6, wherein the silver particles comprise a mixture of spherical silver powder and flake-shaped silver particles.

8. The passivated emitter rear solar cell of claim 1, wherein the electroconductive paste composition further comprises an adhesion promoting additive comprising MnO₂.

9. The passivated emitter rear solar cell of claim 1, wherein the silicone oil is present in the electroconductive paste composition in an amount of about 0.2 to about 3.5 wt %, based upon 100% total weight of the electroconductive paste composition.

10. The passivated emitter rear solar cell of claim 1, wherein the at least one lead-free glass frit comprises:

(i) SiO₂, B₂O₃, and Bi₂O₃, wherein the total content of SiO₂, B₂O₃, and Bi₂O₃ is at least about 70 wt %, based upon 100% total weight of the glass frit;

(ii) at least 5 wt % of at least one alkaline oxide; and

(iii) at least 2 wt % of MoO₃.

11. The passivated emitter rear solar cell of claim 10, wherein the at least one lead-free glass frit further comprises Nb₂O₅ in an amount of less than about 2 wt %, based upon 100% total weight of the glass frit.

12. The passivated emitter rear solar cell of claim 1, further comprising an antireflection layer formed on the front surface of the silicon substrate.

13. The passivated emitter rear solar cell of claim 12, further comprising a front electrode formed on the antireflection layer.

14. The passivated emitter rear solar cell of claim 1, wherein the organic vehicle is present in an amount of at least about 5 wt % and no more than about 60 wt %, based upon 100% total weight of the electroconductive paste composition.

15. The passivated emitter rear solar cell of claim 1, wherein the at least one silicone oil has a viscosity of about 1-40 kcps.

16. A method of preparing a passivated emitter rear solar cell, comprising the steps of:

(i) applying a backside electroconductive paste composition to a rear surface of a silicon substrate having at least one rear passivation layer formed thereon, the rear passivation layer having a plurality of open holes formed therein to expose areas of the silicon substrate;

(ii) applying an aluminum electroconductive paste composition in the open holes of the rear passivation layer to contact the silicon substrate; and

(iii) heating the silicon substrate,

wherein the backside electroconductive paste composition comprises conductive metallic particles, at least one lead-free glass frit, and an organic vehicle comprising at least one silicone oil.

17. The method of claim 16, wherein the silicon substrate further includes a rear capping layer on top of the rear passivation layer.

18. The method of claim 17, wherein the plurality of open holes are formed in the rear passivation layer and rear capping layer.

19. The method of claim 16, wherein step (i) is performed by screen printing.

20. The method of claim 16, wherein step (iii) is performed at temperatures of 700-975°

C.