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Aluminum paste for back electrodes of solar cells

A solar cell and back electrode technology, which is applied in the field of aluminum paste, can solve problems such as poor resistance and uniformity of aluminum paste, and affect the efficiency of solar cells, so as to prevent warping and improve efficiency

Active Publication Date: 2015-11-11
DONGWOO FINE CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these additives are problematic because they exist as residues during the aluminum paste calcination process, or form pores, which reduce the resistance and uniformity of the aluminum paste, thereby adversely affecting the efficiency of the solar cell
In addition, the above aluminum paste is problematic because the aluminum powder has a maximum particle size of 10-20 μm, making it difficult for the aluminum paste to evenly contact the textured back surface of the solar cell, and as a result aluminum bumps may be formed due to the holes formed therein. piece

Method used

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  • Aluminum paste for back electrodes of solar cells
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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Example 1: Preparation of aluminum paste

[0038] 63wt% of D 50 =4~6μm aluminum powder and 7wt% D 50 =2~4μm aluminum powder (4~6μm:2~4μm=9:1 (weight ratio), total amount of aluminum powder=70wt%), 0.5wt% glass frit with the composition ratio shown in Table 1, and A 29.5 wt% organic vehicle solution (prepared by dissolving ethyl cellulose in glycol ether) was sequentially mixed with each other to form a mixture, and then the mixture was stirred at 1000 rpm for 3 minutes using a simultaneous rotating and revolving mixer And prepare aluminum paste.

[0039] [Table 1]

[0040] Component

Embodiment 2

[0041] Example 2: Preparation of aluminum paste

[0042] Prepare aluminum paste in the same manner as in Example 1, except that 42wt% of D is added 50 =4~6μm aluminum powder and 28wt% D 50 = 2~4μm aluminum powder (4~6μm: 2~4μm=6:4 (weight ratio), total amount of aluminum powder=70wt%).

Embodiment 3

[0043] Example 3: Preparation of aluminum paste

[0044] Prepare aluminum paste in the same manner as in Example 1, except that 66.5wt% of D is added 50 =4~6μm aluminum powder and 3.5wt% D 50 = 2~4μm aluminum powder (4~6μm: 2~4μm=9.5:0.5 (weight ratio), total amount of aluminum powder=70wt%).

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Abstract

Disclosed herein is an aluminum paste for a back electrode of a solar cell, comprising: aluminum powder in which aluminum powder having an average particle size (D50) of 4 ~ 6 µm and aluminum powder having an average particle size (D50) of 2 ~ 4 µm are mixed in a ratio of 6:4 ~ 9.5:0.5 by weight. The aluminum paste is advantageous in that since the contact between aluminum paste and a silicon wafer textured using two or more kinds of aluminum powder having a different average particle size is improved, the warpage of a solar cell can be prevented or the formation of aluminum bubbles or bumps and the occurrence of yellow discoloration can be minimized during a calcination process, the values of short circuit current (Isc) and open circuit voltage (Voc) can be greatly increased, and the efficiency of a solar cell can be remarkably improved.

Description

Technical field [0001] The invention relates to an aluminum paste used for the back electrode of a solar cell. Background technique [0002] Generally, crystalline silicon solar cells use a P-type silicon substrate with a thickness of 180-220 μm. On the front surface of the P-type silicon substrate, an N-type impurity layer with a thickness of 0.2 to 0.6 μm is formed, and an anti-reflection SiN is sequentially formed on the N-type impurity layer x Layer and front electrode. In addition, an aluminum electrode is formed on the back surface of the P-type silicon substrate. The aluminum electrode is formed by coating aluminum paste using screen printing or the like, drying the coated aluminum paste, and then calcining the dried aluminum paste at two stages of low temperature (about 600°C) and high temperature (800-950°C). In this firing process, aluminum diffuses into the P-type silicon substrate to form an Al-Si alloy layer. This Al-Si alloy layer forms a back surface field (BSF)...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01B1/22H01L31/0224H01L31/056
CPCH01L31/022425H01B1/22H01L31/056Y02E10/52H01B1/04H01L31/04
Inventor 李昶模李承傭林大成崔亨燮洪胜权
Owner DONGWOO FINE CHEM CO LTD