Solar Battery Element With Variable Thickness Passivation
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Solution Overview
Problem
Crystalline solar battery devices face challenges in improving photoelectric conversion efficiency due to the promotion of minority carrier recombination on the light-receiving surface side, despite effective passivation on the back surface, which reduces efficiency.
Innovation Solution
A solar battery device configuration with a passivation layer on the back surface and an antireflection layer on the light-receiving surface, featuring a variable thickness passivation layer on the light-receiving surface to reduce recombination and enhance absorption, combined with a protective layer to prevent damage and improve adhesion, and the use of aluminum oxide and silicon nitride materials for effective passivation and antireflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is made present on the back-surface side of the semiconductor substrate, then minority carrier recombination is reduced, but photoelectric conversion efficiency is deteriorated due to promotion of recombination on the light-receiving surface side
Solution Approach 1:
The passivation layer is applied selectively to different surfaces of the semiconductor substrate with different thicknesses and properties. The first passivation layer is formed on the back surface with a thickness that reduces minority carrier recombination, while the second passivation layer is formed on the light-receiving surface with optimized thickness to prevent excessive recombination. This local differentiation allows each surface to be optimized for its specific function, resolving the contradiction between reducing recombination and maintaining photoelectric conversion efficiency.
Solution Approach 2:
The passivation function is segmented into two separate passivation layers located on opposite surfaces of the semiconductor substrate. The first passivation layer on the back surface handles minority carrier recombination reduction, while the second passivation layer on the light-receiving surface handles light absorption enhancement and surface recombination control. This segmentation allows independent optimization of each layer's properties to achieve overall system performance improvement.
2Reliability
If a passivation layer is made present on the back-surface side of the semiconductor substrate, then passivation is improved, but structural complexity increases
Solution Approach 1:
The passivation layers serve multiple functions simultaneously: they provide electrical passivation to reduce minority carrier recombination, optical passivation to enhance light absorption by reducing surface reflection, and mechanical protection for the semiconductor substrate. By making the passivation layers multi-functional, the need for separate components is eliminated, maintaining structural simplicity while achieving improved passivation 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
The configuration significantly improves photoelectric conversion efficiency by reducing minority carrier recombination and enhancing light absorption, while maintaining the structural integrity and productivity of the solar battery device manufacturing process.
Implementation Method 1
making a passivation layer present on the back-surface side of the semiconductor substrate
Implementation Method 2
making an antireflection film present on the light-receiving surface side of the semiconductor substrate
Implementation Method 3
crystalline solar battery device using a semiconductor substrate made of monocrystalline or polycrystalline silicon
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A solar battery device includes a semiconductor substrate (1) and a covering part (Pc1). The semiconductor substrate (1) includes a first semiconductor region (3) and a second semiconductor region (2). The first semiconductor region (3) is a first-conductivity-type semiconductor region present on a side of a first surface of the semiconductor substrate (1). The second semiconductor region (2) is a second-conductivity-type semiconductor region different from the first-conductivity-type and located on a side of a second surface that is an opposite side of the semiconductor substrate (1) from the first surface. The covering part (Pc1) is located on the side of the first surface of the semiconductor substrate (1). The covering part (Pc1) includes a laminated portion (Ps1) in which a plurality of layers including a passivation layer (9) and an antireflection layer (5) are present in a laminated state. In the laminated portion (Ps1), the passivation layer (9) includes a region in which a thickness decreases from a side of an outer peripheral portion (1op) toward a side of a central part (1cp) of the first surface.