Conductive Paste for Photovoltaic Cells via Anti-Reflective Layer Etching
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Solution Overview
Problem
Conventional photovoltaic cell manufacturing methods face challenges in achieving high performance due to the need for strong adhesive bonds between conductive metal pastes and substrates, particularly with insulating layers, which affects electrical efficiency and contact resistance.
Innovation Solution
A conductive paste composition comprising electrically conductive metal, alkaline-earth-metal boron bismuth oxide, and an organic vehicle is used, which allows for the formation of robust, low-resistance contacts by etching through anti-reflective layers during firing, enhancing electrical connectivity and adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional conductive metal pastes are used with insulating anti-reflective layers, then the insulating layer provides anti-reflective property, but the paste must penetrate through the insulating layer which increases contact resistance and reduces electrical efficiency
Solution Approach 1:
The patent introduces an intermediary chemical etching mechanism where the conductive paste contains components specifically designed to chemically react with and penetrate the insulating anti-reflective layer. This intermediary action allows the paste to create conductive pathways through the insulating barrier without relying solely on mechanical penetration, thereby reducing contact resistance while maintaining the anti-reflective properties of the layer.
Solution Approach 2:
The patent modifies the chemical composition parameters of the conductive paste to include etching agents and reactive components that can chemically interact with the anti-reflective layer. By changing the chemical parameters of the paste formulation, the paste gains the ability to penetrate through the insulating layer more effectively, creating better electrical contact while preserving the optical properties of the anti-reflective coating.
2Reliability
If strong adhesive bonds are achieved between paste and substrate, then electrical efficiency improves, but the manufacturing process becomes more complex and sensitive to firing conditions
Solution Approach 1:
The conductive paste is formulated with self-adjusting properties where the chemical composition automatically adapts to the firing conditions and substrate type. The paste contains components that self-regulate the bonding process, creating strong adhesive bonds without requiring precise control of external parameters. This self-service mechanism simplifies the manufacturing process while ensuring reliable electrical contact.
Solution Approach 2:
The patent uses composite paste materials combining multiple functional components: conductive metal particles, glass frit for adhesion, organic vehicle for printability, and chemical etching agents. This composite formulation provides multiple functions simultaneously - electrical conductivity, mechanical adhesion, chemical penetration, and process stability - reducing sensitivity to firing conditions while achieving strong bonds and high electrical efficiency.
3Ease of manufacture
If conventional glass frit and conductive species are used, then the paste can be printed and fired, but the electrical contact quality and overall device performance are limited
Solution Approach 1:
The patent changes the chemical composition parameters of the paste by incorporating reactive metal powders, specific glass frit compositions, and organic vehicles with controlled volatility. These parameter changes enhance the paste's ability to penetrate the anti-reflective layer and form low-resistance contacts while maintaining printability and firing characteristics.
Solution Approach 2:
The patent employs composite paste formulations that integrate conductive metal particles, reactive metal powders, glass frit, and organic vehicles in specific ratios. This composite structure provides both ease of printing (through the organic vehicle) and high electrical contact quality (through the reactive components that penetrate and bond with the substrate), overcoming the limitations of conventional single-function paste materials.
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 proposed paste composition improves photovoltaic cell performance by achieving high conversion efficiency, fill factor, and low series resistance, while eliminating the need for lead and cadmium, thereby providing a more environmentally friendly and efficient manufacturing process.
Implementation Method 1
the insulating layer normally must be removed to allow an overlaid front-side electrode to make contact with the underlying semiconductor surface
Implementation Method 2
firing the paste composition and substrate to dissolve or otherwise penetrate the insulating anti-reflective layer
Implementation Method 3
sinter the metal powder, such that an electrical connection with the semiconductor structure is formed
Implementation Method 4
form a strong adhesive bond with the substrate upon firing
Implementation Method 5
a source of electrically conductive metal and the oxide are dispersed
Implementation Method 6
an organic vehicle, in which the source of electrically conductive metal and the oxide are dispersed; functions as a vehicle for printing
Data Source
AI summary
A conductive paste composition contains a source of an electrically conductive metal, an alkaline-earth-metal boron bismuth oxide, and an organic vehicle. An article such as a high-efficiency photovoltaic cell is formed by a process of deposition of the paste composition on a semiconductor substrate (e.g., by screen printing) and firing the paste to remove the organic vehicle and sinter the metal and alkaline-earth-metal boron bismuth oxide.