Solar Cell Metallization With Laser-Reverse Bias Contact Formation

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Solution Overview

Problem

Conventional solar cell preparation methods result in poor photovoltaic conversion performance due to inadequate metallization processes.

Innovation Solution

A method involving laser processing of grid line electrodes and adjacent regions with reverse current application to reverse bias the PN junction, forming metal micelles that reduce contact impedance and enhance photoelectric conversion efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional sintering process is used to form grid line electrodes, then the metal paste can penetrate the passivation layer to contact the doped layer, but the contact impedance is high and photoelectric conversion performance is poor

Engineering Contradiction:

Improvephotoelectric conversion performanceVSAvoidcontact impedance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies laser processing before final sintering to pre-treat the metal paste and create favorable conditions for low-impedance contact. The laser irradiation activates the metal paste, promotes metal ion diffusion, and prepares the interface between metal paste and doped layer, enabling better electrical contact after subsequent sintering.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the physical and chemical parameters of the metal paste through laser irradiation, including temperature elevation, phase transformation, and chemical activation. These parameter changes enable the metal paste to form conductive contact points with the doped layer, reducing contact impedance and improving photoelectric conversion performance.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If laser processing is applied to improve contact quality, then contact impedance is reduced, but additional process complexity is introduced

Engineering Contradiction:

Improvecontact impedanceVSAvoidprocess complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical or thermal processing methods with laser processing to achieve precise local treatment of the metal paste. The laser provides targeted energy delivery that activates the metal paste and promotes ion diffusion without requiring complex mechanical equipment or multiple processing steps.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes phase transitions of the metal paste induced by laser irradiation to achieve the desired contact quality. The laser heating causes phase changes in the metal paste, enabling metal ion diffusion and formation of conductive contact points, thereby reducing contact impedance through controlled phase transformation.

Inventive Principle:

Principle #36Phase transitions

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Improves the filling factor and photoelectric conversion efficiency of solar cells by creating conductive contact points in the doped and passivation layers.

Implementation Method 1

performing laser processing on multiple first grid line electrodes and multiple adjacent regions of the multiple first grid line electrodes

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

promoting the precipitation of metal ions in the multiple first grid line electrodes to form metal micelles

Methodology Applied

Scientific EffectThermal diffusion: Diffusion

Implementation Method 3

a reverse current is applied between the multiple first grid line electrodes and the multiple second grid line electrodes to reverse bias the PN junction during the laser processing

Methodology Applied

Scientific EffectReverse bias: Diode

Implementation Method 4

enhancing carrier generation and metal ion precipitation to form conductive contact points

Methodology Applied

Scientific EffectCarrier generation: Photoelectric Effect

Implementation Method 5

the metallization process includes a sintering operation to sinter metal paste printed on the surface of the silicon wafer

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 6

so that the metal paste can penetrate a passivation layer to be in electrical contact with a doped conductive layer

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20240178341A1Method for preparing solar cell, and solar cell

Publication Date: 2024.05.30 ZHEJIANG JINKO SOLAR CO LTD

AI summary

The method for preparing a solar cell includes providing a substrate having a first surface and a second surface opposite to the first surface; forming a doped layer and a first passivation layer stacked sequentially in a direction away from the substrate on the first surface; forming a second passivation layer on the second surface; forming multiple first grid line electrodes arranged at intervals on the surface of the first passivation layer away from the substrate, and forming multiple second grid line electrodes arranged at intervals on the surface of the second passivation layer away from the substrate; performing a laser processing on the multiple first grid line electrodes and an adjacent region of the multiple first grid line electrodes, and applying a reverse current between the multiple first grid line electrodes and the multiple second grid line electrodes.