Electrically conductive paste for front electrode of solar cell and preparation method thereof

Abstract

The present invention provides an electrically conductive paste for a front electrode of a solar cell and a preparation method thereof. The electrically conductive paste is composed of a corrosion binder, a metallic powder and an organic carrier. The corrosion binder is one or more glass-free Pb—Te based crystalline compounds having a fixed melting temperature in a range of 440° C. to 760° C. During a sintering process of the electrically conductive paste for forming an electrode, the corrosion binder is converted into a liquid for easily corroding and penetrating an antireflective insulating layer on a front side of the solar cell, so that a good ohmic contact is formed. At the same time, the electrically conductive metallic powder is wetted, and the combination of the metallic powder is promoted. As a result, a high-conductivity front electrode of a crystalline silicon solar cell is formed.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application claims priority to a PCT Application No. PCT / CN2013 / 073098, filed on Mar. 22, 2013, commonly assigned and incorporated as reference for all purposes.[0002]The subject matter of the present application is related to China Patent Application No. 201210360864.5, filed on Sep. 25, 2012, by Ran Guo, U.S. patent application Ser. No. 13 / 730,939, filed on Dec. 28, 2012, by Ran Guo, and U.S. patent application Ser. No. 13 / 787,997, filed on Mar. 7, 2013, by Xiaoli Liu et al., commonly assigned and incorporated by reference herein to their entireties for all purposes.BACKGROUND OF THE INVENTION[0003]The present invention relates to the technical field of solar cells, and more particularly to an electrically conductive paste for a front electrode of a solar cell and a preparation method thereof.[0004]Solar energy is an inexhaustible source of clean energy. With the increasing depletion of coal, oil and other non-renewable energy, de...

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Benefits of technology

[0015]The electrically conductive paste used for the manufacture of front side electrodes on solar cell light receiving surface comprises full-crystal corrosion binder and free from any glass material as a binding additive in the paste. By controlling proper metal-oxide materials with selective weight ratio among several ingredients and crystal particle sizes during the preparation of the full-crystal corrosion binder, and further by controlling the way of mixing with metallic powder and organic carrier, the conductive paste bearing this full-crystal corrosion binder can be subjected to a broader range of sintering process conditions to form electrodes on solar cells with greatly reduced series resistance and enhanced photovoltaic conversion efficiency.

Problems solved by technology

Solar energy is an inexhaustible source of clean energy.

In the selection of the glass frit, the composition, softening point, thermal expansion coefficient, wetting properties and amount will affect the physical and chemical changes in the sintering process, thereby affecting the performance of the solar cell.

If the content of the glass frit is low, full contact and complete reaction of the glass frit and the antireflective layer cannot be ensured.

The higher the amount of the glass frit is, the lower the relative content of the electrically conductive metallic phase is, and the lower the probability of contact of metallic particles is, resulting in serious deterioration of conductivity.

But excessively-early softening of the glass frit can clog the communicating pores in the metallic powder, thereby hindering the effective discharge of the organic carrier.

However, regardless the use of various glass frit materials, due to restrictions of the physical properties of the glass frit, the above technical problems still exist, resulting in process difficulties with narrow windows in preparation of a suitable glass frit and a subsequent conductive paste.

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