Selective Doping Structure for Photovoltaic Solar Cells
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Solution Overview
Problem
Existing methods for producing selective doping structures in photovoltaic solar cells are complex and costly, often resulting in significant recombination losses and efficiency reductions due to complex masking steps and inefficient doping profiles.
Innovation Solution
A method involving the application of a doping layer to a semiconductor substrate, followed by local and global heating to create distinct doping profiles, and subsequent removal of surface layers to optimize doping concentrations, eliminating the need for costly masking steps and reducing recombination losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If homogeneous diffusion of emitter area is used, then selective doping structure is formed, but complex masking steps are required increasing device complexity and cost
Solution Approach 1:
The patent extracts and removes the complex masking steps from the diffusion process by using a decoupled approach: first forming a uniform doping layer across the entire surface, then selectively activating doping only in contact areas through localized high-temperature processing. This eliminates the need for physical masks while achieving the same selective doping effect.
Solution Approach 2:
The patent applies preliminary uniform doping to the entire emitter area before selective activation. By pre-diffusing dopant uniformly across the surface and then selectively activating only contact regions through localized heating, the process achieves selective doping without requiring masks during the diffusion step itself.
2Manufacturing precision
If conventional diffusion methods are used, then doping structure is formed, but significant recombination losses occur reducing efficiency
Solution Approach 1:
The patent applies local quality by creating distinct doping profiles in different regions: high doping concentration in contact areas for low contact resistance, and low or zero doping in non-contact areas for reduced recombination. This spatial variation in doping quality optimizes both electrical contact and carrier collection efficiency.
Solution Approach 2:
The patent changes the doping parameter (concentration) selectively across different spatial regions. By controlling dopant diffusion and activation parameters locally - high concentration in contact areas, low concentration elsewhere - the process achieves optimal balance between contact resistance and recombination losses.
3Reliability
If high doping is applied, then low contact resistance is achieved, but recombination of electron-hole pairs increases reducing efficiency
Solution Approach 1:
The patent applies local quality by creating distinct doping profiles in different regions: high doping concentration in contact areas for low contact resistance, and low or zero doping in non-contact areas for reduced recombination. This spatial variation in doping quality optimizes both electrical contact and carrier collection efficiency.
4Loss of energy
If selective emitter structures are formed with transverse conduction, then recombination is reduced, but contact resistance increases
Solution Approach 1:
The patent applies local quality by creating distinct doping profiles in different regions: high doping concentration in contact areas for low contact resistance, and low or zero doping in non-contact areas for reduced recombination. This spatial variation in doping quality optimizes both electrical contact and carrier collection efficiency.
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 enables the cost-effective production of selective doping structures with reduced recombination activity and low contact resistance, enhancing the overall efficiency of photovoltaic solar cells by optimizing doping profiles without the need for complex masking processes.
Implementation Method 1
liquid -liquid diffusion dopant diffuses from the doping layer into the melted semiconductor substrate
Implementation Method 2
local heating of a melting area of the doping layer and a melting area of the semiconductor substrate lying below the doping layer in such a way that a melt mixture is formed
Implementation Method 3
the semiconductor substrate is globally heated, in such a way that dopant diffuses from the doping layer into the semiconductor substrate
Data Source
Figure 1A~1C
Figure 1D~1E1
Figure 2A~2C
AI summary
The invention relates to a method for producing a selective doping structure in a semiconductor substrate in order produce a photovoltaic solar cell. The method comprises the following steps: A) applying a doping layer (2) to the emitter side of the semiconductor substrate, B) locally heating a melting region of the doping layer (2) and a melting region of the semiconductor substrate lying under the doping layer (2) in such a way that dopant diffuses from the doping layer (2) into the melted semiconductor substrate by means of liquid-liquid diffusion, so that a high doping region (3) is produced after the melt mixture solidifies, C) producing the planar low doping region by globally heating the semiconductor substrate, D) removing the doping layer (2) and E) removing or converting a layer of the semiconductor substrate on the doping side in such a way that part of the low doping region and of the high doping region close to the surface is removed or is converted into an electrically non-conducting layer.