One-Step Non-Contact Printing for Solar Cell Electrodes
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Solution Overview
Problem
Conventional non-contact printing methods for silicon solar cells require a two-step process due to the inability of conventional Ag inks to etch silicon nitride and silicon oxide layers, leading to inefficiency and high manufacturing costs, especially for thin solar cells where contact printing can cause substrate damage.
Innovation Solution
A liquid additive containing metal nitrates or acetates, such as lead nitrate and zinc nitrate, is mixed with a metal ink to etch silicon nitride or silicon oxide layers during a one-step non-contact printing process, allowing for the simultaneous etching and formation of electrodes by firing at temperatures below 800°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional non-contact printing method is used with conventional Ag ink, then substrate damage is prevented, but the process requires two-step printing (etching + electrode formation) leading to manufacturing inefficiency
Solution Approach 1:
The patent combines the etching function and electrode formation function into a single metal ink composition. The ink simultaneously contains glass powder (for etching SiNx/SiO2 layers) and metal particles (for electrode formation), allowing both functions to be performed in one printing and firing step, thus eliminating the need for separate etching and electrode formation processes.
Solution Approach 2:
The metal ink is designed to perform multiple functions: it acts as both an etching agent (through glass powder that removes insulating layers) and an electrode-forming material (through metal particles that create conductive contacts). This multi-functional ink enables a single-step process that maintains substrate integrity while improving manufacturing efficiency.
2Device complexity
If nano-sized glass powder is mixed with Ag ink for one-step non-contact printing, then manufacturing process is simplified, but uniform dispersion is difficult and manufacturing cost increases
Solution Approach 1:
The patent introduces organic solvent as an intermediary medium to achieve uniform dispersion of glass powder and metal particles. The solvent allows both components to be dissolved or suspended homogeneously before printing, and after firing, the solvent evaporates leaving behind uniformly distributed functional materials. This resolves the dispersion issue without requiring complex mixing equipment.
Solution Approach 2:
The patent changes the physical state of the ink components from solid powder mixtures to dissolved/suspended states in organic solvent. This parameter change (from solid to liquid phase) enables uniform mixing and dispersion, and after printing and firing, the solvent evaporates to restore the functional materials in their effective forms, achieving both process simplification and uniform dispersion.
3Reliability
If conventional Ag ink is used for non-contact printing, then substrate damage is avoided, but additional etching material cost is required
Solution Approach 1:
The patent merges the etching material (glass powder) and electrode material (metal particles) into a single ink composition, eliminating the need for separate etching material application. This combined approach reduces the total quantity of materials required and simplifies the material supply chain while maintaining substrate integrity through non-contact printing.
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 simplifies the manufacturing process for thin silicon solar cells by enabling a single-step formation of electrodes without substrate damage, reducing costs and improving efficiency by etching silicon nitride or silicon oxide layers and forming ohmic contacts in a single step.
Implementation Method 1
A liquid additive containing a metal nitrate or a metal acetate... etching silicon nitride or silicon oxide layers
Implementation Method 2
reacts with the silicon substrate to form metal crystallites on the surface of the silicon substrate. The metal crystallites form ohmic contact with the p-type or n-type silicon substrate
Implementation Method 3
a liquid additive containing a metal nitrate or a metal acetate, and an organic solvent
Data Source
AI summary
The present invention relates to a liquid additive for etching silicon nitride and silicon oxide layers, a metal ink including the same for forming silicon solar cell electrodes and a method for manufacturing silicon solar cell electrodes. More particularly, it relates to a liquid additive including metal nitrate, metal acetate, or hydrates thereof and a metal ink for forming silicon solar cell electrodes, mixed with the liquid additive and a metal. Further, it relates to a method for manufacturing silicon solar cell electrodes comprising a one-step non-contact printing for etching of a silicon nitride layer or silicon oxide layer and forming electrodes.