Passivated Solar Cell Contact Etching for Uniform Silicon Roughness
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Solution Overview
Problem
Existing surface treatment methods for forming passivated contacts in solar cells face challenges with high etch rates and non-uniformity due to high concentrations of chemicals, which are difficult to control and result in suboptimal surface morphology, affecting solar cell efficiency.
Innovation Solution
A two-step etching process using a first etchant to smooth the silicon layer and a second etchant with a slower etching rate to achieve desired roughness, where the second etchant is a single component solution like sodium hypochlorite, allowing for controlled surface treatment and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high concentration chemical mixtures are used for etching, then etch rate is improved, but manufacturing precision deteriorates due to non-uniformity and difficulty in control
Solution Approach 1:
The patent divides the single etching process into two sequential etching steps using different etchants. The first etching step uses a first etchant to perform aggressive material removal, while the second etching step uses a second etchant to perform controlled, uniform etching. This segmentation allows the system to achieve both high productivity in the first step and high manufacturing precision in the second step, resolving the contradiction between etch rate and surface morphology uniformity.
2Productivity
If high concentration chemical mixtures are used for etching, then etch rate is improved, but manufacturing precision deteriorates due to difficulty in control
Solution Approach 1:
The patent segments the etching process into two distinct steps with different etchants having different etch rates. The first etching step with the first etchant achieves rapid material removal, while the second etching step with the second etchant provides precise control over final etch depth and surface morphology. This segmentation enables the system to achieve both high productivity and precise manufacturing control.
3Productivity
If high concentration chemical mixtures are used for etching, then etch rate is improved, but device complexity increases due to mixing requirements
Solution Approach 1:
The patent segments the etching process into two separate steps using different etchants, where the second etchant can be a single component solution. This segmentation eliminates the need for complex mixing systems required for multi-component high-concentration etchants, while still achieving high etch rates in the first step and controlled etching in the second step, thus resolving the contradiction between productivity and device complexity.
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 method improves the surface roughness and morphology of the silicon layer, leading to higher fill factors and solar cell efficiency by providing a controlled and uniform etching process, reducing costs and environmental impact.
Implementation Method 1
etching a portion of the silicon layer using a first etchant to reduce surface protrusions of the textured surface
Implementation Method 2
etching the intermediate surface of the silicon layer using a second etchant to form a treated surface of the silicon layer having a desired roughness
Data Source
AI summary
Surface treatment method for forming a passivated contact of a solar cell A surface treatment method for forming a passivated contact of a solar cell 100 is described. In an embodiment, the solar cell 100 comprises a silicon layer 102 having a textured surface, and the method comprises: (i) etching a portion of the silicon layer 102 using a first etchant to reduce surface protrusions of the textured surface and to provide an intermediate surface of the silicon layer 102; and (ii) etching the intermediate surface of the silicon layer 102 using a second etchant to form a treated surface of the silicon layer 102 having a desired roughness for forming the passivated contact of the solar cell, the second etchant having a slower etching rate on silicon than that of the first etchant.