Solar Cell Collecting Electrode Low-Melting-Point Material Annealing
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Solution Overview
Problem
Existing methods for forming collecting electrodes in solar cells face challenges such as high manufacturing costs, non-uniform thickness, and increased resistance due to the use of resist materials and high-temperature processes, which affect the conversion efficiency and cost-effectiveness of solar cells.
Innovation Solution
A solar cell design featuring a collecting electrode with a first electroconductive layer made of low-melting-point material, a second electroconductive layer, and an insulating layer, where the low-melting-point material undergoes thermal fluidization during an annealing step to form openings in the insulating layer, allowing for plating without a resist material and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a silver paste containing resin is used to form the collecting electrode by screen printing, then the process is simple, but the material cost increases and the resistivity of the collecting electrode increases
Solution Approach 1:
The invention changes the material composition parameters by replacing resin-based silver paste with metal powder and organic solvent mixture, and changes the processing parameters by using lower temperature annealing (100-250°C) instead of conventional high-temperature firing, thereby reducing resistivity while maintaining processability
Solution Approach 2:
The invention replaces expensive silver paste with a more cost-effective formulation using metal powder and organic solvent, achieving lower material cost while maintaining or improving electrical conductivity through the new processing approach
2Reliability
If the print thickness of silver paste is increased to decrease resistivity, then the resistivity decreases, but the line width of the electrode increases causing increased shading loss
Solution Approach 1:
The invention changes the physical state parameters of the metal material from paste form to fine powder form, enabling better distribution and thinner effective conductive paths while maintaining low resistivity through improved contact and the annealing process
Solution Approach 2:
The invention segments the metal material into fine powder particles that can be uniformly distributed and sintered during annealing, creating a network of conductive paths that achieve low resistivity without requiring thick continuous layers, thereby reducing shading loss
3Ease of manufacture
If a plating method is used to form the collecting electrode, then material and process costs decrease, but a resist material layer is required which complicates the process and increases manufacturing costs
Solution Approach 1:
The invention extracts and removes the resist material layer from the conventional plating process by using a direct metal powder deposition and annealing method that does not require resist patterning, thereby simplifying the overall manufacturing process while maintaining cost advantages
Solution Approach 2:
The invention replaces the mechanical/chemical resist-based patterning system with a direct deposition and thermal processing system, substituting complex multi-step processes with a simpler sequence of metal powder application and annealing
4Manufacturing precision
If a resist material layer is formed and then removed after plating, then the collecting electrode shape is defined, but the process becomes complicated and manufacturing costs increase
Solution Approach 1:
The invention performs preliminary action by directly depositing metal powder in the desired electrode pattern configuration before annealing, eliminating the need for subsequent resist removal steps while maintaining precise shape definition through controlled deposition
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
This approach improves the conversion efficiency of solar cells by reducing resistance and manufacturing costs, enabling the formation of collecting electrodes with improved uniformity and efficiency without the need for expensive resist materials or high-temperature processes.
Implementation Method 1
the low-melting-point material undergoes thermal fluidization during an annealing step to form openings in the insulating layer
Data Source
AI summary
Disclosed is a solar cell having a collecting electrode on one main surface of a photoelectric conversion section. The collecting electrode includes a first electroconductive layer and a second electroconductive layer in this order from the photoelectric conversion section side, and further includes an insulating layer between the first electroconductive layer and the second electroconductive layer. The first electroconductive layer includes a low-melting-point material, and a part of the second electroconductive layer is conductively connected with the first electroconductive layer through, for example, an opening in the insulating layer. The second electrode layer is preferably formed by a plating method. In addition, it is preferable that before forming the second electroconductive layer, annealing by heating is carried out to generate the opening section in the insulating layer.