Solar Cell Metallization Using Laser-Assisted Reverse Bias
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Solution Overview
Problem
The photoelectric conversion performance of conventional solar cells is poor due to inadequate metallization processes that fail to effectively form conductive contact points between grid line electrodes and the doped conductive layer.
Innovation Solution
A method involving laser processing on grid line electrodes and applying a reverse current to reverse bias the PN junction, promoting the precipitation of metal ions to form metal micelles that reduce contact impedance and improve photoelectric conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sintering process is used to form grid line electrodes, then the metallization process can be completed, but the contact impedance between grid line electrodes and doped conductive layer remains high, resulting in poor photoelectric conversion performance
Solution Approach 1:
The patent applies reverse bias to the PN junction before and during the laser processing step, which preliminarily prepares the junction by generating carriers and promoting metal ion precipitation. This preliminary action enhances the formation of conductive contact points between the grid line electrodes and the doped conductive layer, thereby reducing contact impedance and improving photoelectric conversion performance without complicating the overall manufacturing process
Solution Approach 2:
The patent changes the electrical parameter of the PN junction by applying reverse bias voltage during laser processing. This parameter change modifies the electrical state of the junction, promoting carrier generation and metal ion precipitation, which leads to better conductive contact formation and reduced contact impedance while maintaining the existing sintering process
2Manufacturing precision
If laser processing is applied to grid line electrodes without reverse bias, then processing can be completed, but metal ion precipitation is insufficient, resulting in inadequate conductive contact points and high contact impedance
Solution Approach 1:
The patent introduces a feedback mechanism where the reverse bias applied to the PN junction during laser processing dynamically promotes carrier generation and metal ion precipitation. This feedback loop enhances the laser processing effectiveness by continuously supplying carriers that facilitate conductive contact point formation, improving manufacturing precision while optimizing energy utilization through controlled electrical stimulation
3Reliability
If reverse current is applied during laser processing, then metal ion precipitation is promoted and conductive contact points are improved, but the process complexity increases
Solution Approach 1:
The patent makes the power supply device perform multiple functions: it not only provides the reverse bias voltage for the PN junction but also controls the laser processing parameters. This multi-functionality approach improves carrier transmission and conductive contact formation without significantly increasing overall system complexity, as the same power supply unit handles both electrical and optical process control
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
The method enhances the filling factor and photoelectric conversion efficiency of solar cells by reducing contact impedance and improving carrier transmission through the formation of conductive contact points.
Implementation Method 1
performing laser processing on the at least one of a first region and a second region
Implementation Method 2
promoting the precipitation of metal ions to form metal micelles
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
Implementation Method 4
the metallization process includes a sintering operation to sinter metal paste printed on the surface of the silicon wafer
Implementation Method 5
so that the metal paste can penetrate a passivation layer to be in electrical contact with a doped conductive layer
Data Source
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.