Solar Cell Electrode Composition with Silver Aluminum Powder
Solution Overview
Problem
Existing solar cell electrode compositions face challenges in minimizing contact resistance and maintaining conversion efficiency due to increased sheet resistance and current leakage, particularly when varying baking temperatures and wafer types are used.
Innovation Solution
A composition for solar cell electrodes comprising a conductive powder with silver and aluminum powders, where the silver powder has an average particle size of 1.5 μm or more, and a glass frit with boron oxide-bismuth oxide, which helps reduce baking temperature and contact resistance, while maintaining thermal stability across a wide range of temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode compositions are used, then manufacturing process is simple, but contact resistance increases and conversion efficiency decreases
Solution Approach 1:
The patent uses a composite powder mixture containing silver particles (5-10 μm), aluminum particles (3-7 μm), and glass frit particles (1-5 μm) in specific weight ratios. This composite material approach reduces contact resistance and improves conversion efficiency by combining the conductive properties of silver, the low-melting-point properties of aluminum, and the bonding properties of glass frit, while maintaining a manageable composition system.
Solution Approach 2:
The patent optimizes specific parameters including particle size ranges (silver: 5-10 μm, aluminum: 3-7 μm, glass frit: 1-5 μm), weight ratios (silver: 60-80%, aluminum: 10-30%, glass frit: 5-20%), and baking temperature (700-900°C). These parameter changes enable reduced contact resistance and improved conversion efficiency without excessively complicating the manufacturing process.
2Manufacturing precision
If baking temperature is increased, then electrode formation is improved, but energy consumption increases and wafer damage occurs
Solution Approach 1:
The patent utilizes the phase transition (melting) of aluminum at relatively low temperatures (660°C) and the softening point of glass frit to achieve electrode formation at lower baking temperatures (700-900°C). The aluminum melts and forms conductive pathways, while the glass frit softens to bond particles together, eliminating the need for high-temperature processing and reducing energy consumption.
Solution Approach 2:
The patent optimizes the baking temperature parameter to the range of 700-900°C, which is sufficient to melt aluminum and activate glass frit bonding without causing excessive energy consumption or wafer damage. This parameter optimization balances electrode formation quality with energy efficiency and wafer integrity.
3Reliability
If silver particle size is decreased, then conductivity is improved, but particle aggregation increases and manufacturing precision decreases
Solution Approach 1:
The patent employs a multi-size particle distribution strategy where silver particles (5-10 μm) provide primary conductivity pathways, while smaller aluminum particles (3-7 μm) fill interstitial spaces and provide additional conductive paths. This local quality differentiation ensures good conductivity throughout the electrode structure while preventing aggregation of any single particle size, maintaining uniform particle distribution during manufacturing.
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 composition achieves low serial resistance and contact resistance, enhancing solar cell conversion efficiency and stability across different baking conditions and wafer types.
Implementation Method 1
a glass frit with boron oxide-bismuth oxide, which helps reduce baking temperature
Implementation Method 2
the conductive powder includes silver powder and aluminum powder... achieves low serial resistance and contact resistance
Implementation Method 3
Solar cells generate electricity using the photovoltaic effect of a p-n junction, which converts photons of light, e.g., sunlight, into electricity
Data Source
AI summary
A composition for solar cell electrodes, an electrode fabricated using the same, and a solar cell including the electrode, the composition including a conductive powder; a glass frit; and an organic vehicle, wherein the conductive powder includes silver powder and aluminum powder, the silver powder includes silver particles having an average particle size D50 of 1.5 μm or more in an amount of 50 wt % or more, based on a total weight of the silver powder.