Solar Cell Aluminum Oxide Passivation With Fire-Through Contacts
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Solution Overview
Problem
Aluminum oxide films used in solar cells have poor fire-through capability during electrode formation, leading to increased electric resistance and complex, costly manufacturing processes, which hinder the production of high-efficiency solar cells with low costs.
Innovation Solution
A solar cell design featuring a passivation layer with an aluminum oxide film of up to 40 nm thickness, allowing for effective fire-through capability during electrode formation without the need for expensive patterning techniques or high-temperature annealing, using a conductive paste that penetrates through the film to establish electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum oxide film is used for passivation layer, then passivation performance is improved, but fire-through capability deteriorates leading to increased electric resistance
Solution Approach 1:
The patent changes the thickness parameter of the aluminum oxide film from conventional thicker layers to a specific thin range of 5-40 nm. This parameter change enables the film to maintain excellent passivation performance while allowing conductive paste to penetrate through during the firing process, thereby resolving the contradiction between passivation quality and fire-through capability.
2Reliability
If conventional aluminum oxide film is used, then passivation is achieved, but additional annealing steps are required increasing manufacturing complexity
Solution Approach 1:
The patent merges the passivation layer formation and electrode formation processes into a single integrated step. The thin aluminum oxide film (5-40 nm) is designed to be penetrable by conductive paste during normal firing temperature, eliminating the need for separate annealing steps. This combines multiple functions into one process, reducing manufacturing complexity while maintaining passivation effectiveness.
3Reliability
If thicker aluminum oxide film is used, then passivation coverage is improved, but electrode contact resistance increases
Solution Approach 1:
The patent optimizes the thickness parameter of the aluminum oxide film to a specific range of 5-40 nm. This precise parameter control ensures sufficient passivation coverage while maintaining adequate fire-through capability for electrode contact. The thin film thickness allows conductive paste to penetrate and establish good electrical contact without compromising the passivation function.
4Manufacturing precision
If expensive patterning techniques are used to form electrodes through aluminum oxide film, then electrode contact is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the thickness parameter of the aluminum oxide film to 5-40 nm, which enables conventional screen printing and firing processes to achieve adequate electrode contact without requiring expensive additional patterning techniques. This parameter optimization allows standard manufacturing equipment and processes to be used, significantly reducing manufacturing costs while maintaining acceptable electrode contact quality.
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 enables satisfactory passivation and tight electrical contact between the substrate and electrodes, reducing manufacturing costs and improving solar cell efficiency by eliminating the need for additional annealing steps and expensive materials.
Implementation Method 1
A layer including an aluminum oxide film having a thickness of up to 40 nm is formed as the passivation layer, which provides for a fire-through capability during electrode formation
Implementation Method 2
Silicon nitride and analogous films are known to have positive charges and thus exert the field effect passivation
Data Source
AI summary
A solar cell is provided with: a semiconductor substrate having a light-receiving surface and a non-light-receiving surface; a PN junction section formed on the semiconductor substrate; a passivation layer formed on the light-receiving surface and/or the non-light-receiving surface; and power extraction electrodes formed on the light-receiving surface and the non-light-receiving surface. The solar cell is characterized in that the passivation layer includes an aluminum oxide film having a thickness of 40 nm or less. As a result of forming a aluminum oxide film having a predetermined thickness on the surface of the substrate, it is possible to achieve excellent passivation performance and excellent electrical contact between silicon and the electrode by merely firing the conductive paste, which is conventional technology. Furthermore, an annealing step, which has been necessary to achieve the passivation effects of the aluminum oxide film in the past, can be eliminated, thus dramatically reducing costs.