Back Contact Solar Cell Manufacturing via Localized Phosphorus Diffusion
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Solution Overview
Problem
Conventional solar cell manufacturing processes are complex and inefficient, particularly in forming high-efficiency back contact solar cells, as they require precise patterning and multiple steps for diffused regions and metallization, leading to shading and resistive losses.
Innovation Solution
A simplified method for manufacturing high-efficiency back contact solar cells using localized phosphorus diffused areas on the rear side, achieved through boron diffusion and a phosphorus-containing doping paste, allowing for blanket doping and interdigitated patterns, which simplifies the process and reduces losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional front-contacted solar cell architecture is used, then manufacturing process is simpler, but shading losses increase and efficiency decreases
Solution Approach 1:
The patent inverts the conventional solar cell architecture by moving all metal contacts from the front surface to the rear surface. This inversion eliminates front surface shading losses while maintaining manufacturing feasibility through the described process steps for forming n+ and p+ diffused regions on the rear surface.
2Loss of energy
If metal contacts are moved to rear side, then shading losses are eliminated, but manufacturing complexity increases due to precise patterning requirements
Solution Approach 1:
The patent segments the rear surface into distinct n+ diffused regions and p+ diffused regions that are interleaved. This segmentation allows for simplified blanket patterning approaches where the entire rear surface is doped uniformly, and subsequent processing naturally creates the interdigitated contact pattern without requiring complex step-by-step patterning.
Solution Approach 2:
The patent merges the formation of n+ and p+ regions into a single blanket doping step followed by selective removal. Instead of separately patterning and doping different regions, the entire rear surface is doped in one step, then unneeded areas are removed, simplifying the manufacturing process while achieving the required interdigitated pattern.
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 enhances solar cell efficiency by enabling wider metal contacts, reducing resistive losses, and simplifying integration, while maintaining high performance and efficiency.
Implementation Method 1
heating the silicon substrate in a drive-in ambient to a drive-in temperature and for a drive-in time period in order to locally diffuse phosphorus into the rear surface of the silicon substrate
Implementation Method 2
locally diffuse phosphorus into the rear surface of the silicon substrate, thereby forming a rear side n+ region
Data Source
AI summary
A method for manufacturing back contact solar cells, comprising steps of: (a) providing a silicon substrate doped with phosphorus; (b) doping the front surface and the rear surface of the substrate homogeneously with boron in a blanket pattern, thereby forming a front side p+ region on the front surface and a rear side p+ region on the rear surface; (c) forming a silicon dioxide layer on the front surface and the rear surface; (d) depositing a phosphorus-containing doping paste on the silicon dioxide layer of the rear surface in a second pattern; (e) heating the silicon substrate in order to locally diffuse phosphorus into the rear surface of the silicon substrate, thereby forming a rear side n+ region on the rear surface of the silicon substrate beneath the phosphorus-containing doping paste; and (f) removing the silicon dioxide layer from the silicon substrate.