Conductive Paste Sintering Inhibitor for Photovoltaic Cells
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Solution Overview
Problem
Conventional electrically conductive pastes for photovoltaic cells often result in poor contact and cracking issues when forming electrodes on semiconductor substrates, leading to high failure rates and reduced reliability of photovoltaic cell elements.
Innovation Solution
An electrically conductive paste comprising silver powder, glass frit, and a sintering inhibitor such as alumina, silicon oxide, or silicon carbide, which inhibits sintering of the silver powder, thereby reducing stress and improving adhesion and contact resistance between the electrode and the semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass frit is added to improve contact between electrode and semiconductor substrate, then contact quality improves, but cracking occurs in the substrate surface
Solution Approach 1:
A sintering inhibitor is introduced as an intermediary substance between the glass frit and silver powder. This inhibitor prevents direct sintering of silver particles while allowing glass frit to maintain good contact with the semiconductor substrate, thus achieving reliable electrical contact without substrate cracking.
Solution Approach 2:
The patent changes the sintering behavior parameter of the paste by adding a sintering inhibitor. This modifies the thermal processing characteristics during firing, preventing excessive silver particle sintering that would otherwise cause stress concentration and cracking in the substrate, while maintaining adequate glass frit flow for good contact.
2Reliability
If silver powder sinters to improve conductivity, then electrical performance improves, but stress increases causing cracking and peeling
Solution Approach 1:
The sintering inhibitor acts as a physical barrier between silver powder particles during the firing process. It allows sufficient sintering to occur for good electrical conductivity while limiting excessive particle fusion that would generate stress and cause substrate cracking or electrode peeling.
Solution Approach 2:
The patent modifies the sintering kinetics by introducing a sintering inhibitor, which changes the temperature-time profile characteristics. This controlled sintering approach achieves the necessary electrical conductivity while maintaining substrate mechanical integrity by preventing stress concentration.
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 use of the described paste reduces the occurrence of poor contact and cracking, enhancing the reliability and production efficiency of photovoltaic cell elements by maintaining better adhesion and contact resistance, thus improving the overall performance and durability of the cells.
Implementation Method 1
a sintering inhibitor that inhibits sintering of the silver powder
Data Source
AI summary
A conductive paste for a photovoltaic cell and a method for producing the photovoltaic cell are disclosed. The conductive paste includes a silver powder, glass frit and a sintering inhibitor that suppresses sintering of the silver powder. The sintering inhibitor contains at least one substance selected from aluminum oxide, silicon oxide and silicon carbide. The method includes forming a first anti-reflective layer on a first region of a main surface of a semiconductor substrate; forming a second anti-reflection layer on a second region of the main surface which is different from the first region; coating the electrically conductive paste onto the second anti-reflective layer on the second anti-reflection layer; and forming a surface electrode in the second region by reacting the second anti-reflection layer with the electrically conductive paste at an elevated temperature.