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Back point-contact silicon solar cell based on silk-screen printing technology and making method

A technology of point contact on the back and silicon solar cells, which is applied in the field of solar cells, can solve problems such as the influence of battery open circuit voltage and short circuit current, poor surface state, adverse effects of battery efficiency, etc., and achieve the effect of simple and practical manufacturing method and improved performance

Inactive Publication Date: 2009-04-29
WUXI SUNTECH POWER CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] The back of the solar cell produced by the conventional screen printing process is a full-area metal contact, without surface passivation, and the surface state is poor. The open circuit voltage and short circuit current of the cell are greatly affected, and the adverse effect on cell efficiency is obvious.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] Basic requirements for silicon wafers: p-type silicon wafers, resistivity: 0.5~10Ω-CM, thickness: 250~400μm.

[0053] The production process is:

[0054] cleaning;

[0055] Suede production: (1) Alkali corrosion (usually 100 crystal orientation single crystal silicon). Corrosion depth 5 ~ 15μm.

[0056] (2) Acid etching (usually monocrystalline silicon or polycrystalline silicon other than 100 crystal orientation) etching depth of 5-15 μm.

[0057] (3) Cleaning, HF rinse

[0058] Phosphorus diffusion: sheet resistance 50~100Ω-CM

[0059] Silicon nitride deposited on both sides: PECVD, thickness ~ 1000 .

[0060] Or thermally oxidized silica: thickness ~ 1000 .

[0061] Laser engraved point contact area on the back: the point contact area ratio is 0.5-20%, and the point contact depth is 3-5 μm.

[0062] Alkali corrosion, cleaning.

[0063] The positive electrode is screen-printed on the front side and sintered.

[0064] Full area back metal screen printed on...

Embodiment 2

[0066] Basic requirements for wafers: p-type silicon wafers, resistivity: 0.5~10Ω-CM, thickness: 250~400μm.

[0067] to clean

[0068] Suede production: (1) Alkali corrosion (usually 100 crystal orientation single crystal silicon). Corrosion depth 5 ~ 15μm.

[0069] (2) Acid etching (usually monocrystalline silicon or polycrystalline silicon other than 100 crystal orientation) etching depth of 5-15 μm.

[0070] (3) Cleaning, HF rinse

[0071] Phosphorus diffusion: sheet resistance 50~100Ω-CM

[0072] Silicon nitride deposited on both sides: PECVD, thickness ~ 1000 .

[0073] Or thermally oxidized silica: thickness ~ 1000 .

[0074] Laser engraved point contact area on the back: the point contact area ratio is 0.5-20%, and the point contact depth is 3-5 μm.

[0075] Alkali corrosion, cleaning.

[0076] Boron diffusion: sheet resistance 50~200Ω-CM

[0077] The positive electrode is screen-printed on the front side and sintered.

[0078] Full area back metal screen p...

Embodiment 3

[0080] Basic requirements for silicon wafers: p-type silicon wafers, resistivity: 0.5~10Ω-CM, thickness: 250~400μm.

[0081] to clean

[0082] Suede production: (1) Alkali corrosion (usually 100 crystal orientation single crystal silicon). Corrosion depth 5 ~ 15μm.

[0083] (2) Acid etching (usually monocrystalline silicon or polycrystalline silicon other than 100 crystal orientation) etching depth of 5-15 μm.

[0084] (3) Cleaning, HF rinse

[0085] Phosphorus diffusion: sheet resistance 50~100Ω-CM

[0086] Silicon nitride deposited on both sides: PECVD, thickness ~ 1000 ;

[0087] Or thermally oxidized silica: thickness ~ 1000 .

[0088] The positive electrode is screen-printed on the front side and sintered.

[0089] Back metal with back screen printed point contacts, sintered.

[0090] Back screen printing back metal, low temperature sintering.

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Abstract

Phosphorus diffusion formed PN junction is setup on P type silicon chip. There is silicon nitride layer, or surface passivation layer of silica, reflection reducing coating and positive electrode on front face. Characters are that through P type punctual alloy diffusion zone, back metal layer of silicon chip constitutes ohmic contact. Preparing method includes steps: selecting P type chip; preparing knap surface and cleaning; forming PN junction through phosphorus diffusion; etching and corroding edges by using plasma; developing silicon nitride or silica at both sides; preparing point contacted dense P+ zone at back side through screen printing by using solid-solid phase diffusion or selective gaseous phase diffusion; printing and sintering electrode through screen printing; adding metal layer to full back side. The solar cell reaches indexes: open circuit voltage larger than 650mV, current density larger than 38mA / cm2, fill factor as 74úÑ-78úÑ and conversion efficiency 18úÑ-20úÑ.

Description

technical field [0001] The invention relates to a solar cell, in particular to a method for manufacturing a backside point-contact silicon solar cell with high efficiency and low cost based on a screen printing process. Background technique [0002] The silicon solar cell is actually a PN junction device. The photo-generated carriers generated by the light are swept to both sides of the PN junction through the electric field of the PN junction to form a photo-generated current to achieve the effect of photoelectric conversion. In order to increase photogenerated carriers, the surface of the solar cell is made into a textured or pyramid-like structure to increase light absorption, and an anti-reflection film is used to reduce light reflection. In order to reduce the recombination of photogenerated carriers, structures or measures to reduce the recombination mechanism are added in the silicon body and surface. In the body, high-purity, defect-free, low-oxygen silicon single c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L31/042H01L31/18
CPCY02E10/52Y02E10/547H01L31/1804H01L31/068Y02P70/50
Inventor 江菲菲
Owner WUXI SUNTECH POWER CO LTD
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