Interdigitated Back Contact Solar Cell Dopant Patterning
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Solution Overview
Problem
Current dopant patterning techniques for interdigitated back contact (IBC) solar cells are costly and lack precision, hindering the production of high-efficiency IBC solar cells due to shading losses and shunting issues.
Innovation Solution
A method involving the formation of alternating regions of n-type and p-type amorphous hydrogenated silicon on an intrinsic amorphous hydrogenated silicon layer, followed by annealing to diffuse dopants and crystallize into polysilicon, using either a deposited mask or shadow mask technique to achieve precise doping patterns without shading losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation through a mask or plasma immersion ion implantation (PIII) through a mask is used for dopant patterning, then doping precision may be improved, but manufacturing cost increases
Solution Approach 1:
The patent uses a sacrificial organic mask layer that is deposited, patterned, and then completely removed after serving its purpose. This disposable mask approach avoids the need for expensive reusable masks and complex mask alignment systems, achieving precise dopant patterning through a cost-effective, single-use masking strategy
Solution Approach 2:
The patent replaces mechanical mask-based dopant delivery systems with a chemical approach where dopants are incorporated during the deposition of the organic mask layer itself. The dopants are then released through thermal decomposition, substituting mechanical implantation with a thermal-chemical process that is both precise and cost-effective
2Device complexity
If conventional dopant patterning techniques are used, then process simplicity may be maintained, but doping precision deteriorates leading to shunting issues
Solution Approach 1:
The patent combines multiple functions into a single organic mask layer: it serves as the patterning mask, contains the dopants, provides thermal stability during processing, and acts as a sacrificial layer for gap formation. This merging of functions achieves precise dopant patterning without requiring multiple separate process steps
Solution Approach 2:
The organic mask layer is formulated as a composite material containing carbon, hydrogen, oxygen, and dopant elements (phosphorus, boron, or antimony). This composite structure enables simultaneous achievement of precise patterning, dopant delivery, and thermal stability, resolving the contradiction between process simplicity and doping precision
3Productivity
If heavily doped p-type and n-type regions are placed close together to reduce shading losses, then cell efficiency improves, but shunting risk increases due to insufficient separation
Solution Approach 1:
The patent introduces an intrinsic semiconductor layer as an intermediary between the heavily doped p-type and n-type regions. This intermediate layer acts as a buffer that prevents direct electrical contact between oppositely doped regions, eliminating shunting paths while allowing the doped regions to be positioned close together for maximum light absorption and cell 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 reliable, precise, and cost-effective dopant patterning, enhancing the efficiency of IBC solar cells by preventing shunting and reducing shading losses, thereby improving the overall performance of the solar cells.
Implementation Method 1
annealing the first layer and the second layer such that dopants from the first layer diffuse into the second layer
Implementation Method 2
the first layer and the second layer crystallize into polysilicon
Data Source
AI summary
Methods of forming interdigitated back contact (IBC) layers are provided. According to an aspect of the invention, a first layer having alternating regions of n-type amorphous hydrogenated silicon and p-type amorphous hydrogenated silicon is formed on a second layer of intrinsic amorphous hydrogenated silicon. The first layer and the second layer are then annealed, such that dopants from the first layer diffuse into the second layer, and the first layer and the second layer crystallize into polysilicon.