Tunnel Back Contact Solar Cell Isolation for Lower Optical Loss
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Solution Overview
Problem
The manufacturing process of tunnel back contact (TBC) solar cells is complex and costly due to the multiple steps required for creating passivated contact structures on silicon substrates, which hinders mass production and increases production costs.
Innovation Solution
A method involving sequential stacking of tunnel oxide layers and intrinsic amorphous silicon layers on a substrate, followed by selective doping and removal processes to form isolation structures, reducing the number of manufacturing steps and improving efficiency by preventing excessive diffusion and enhancing light utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full passivation structure is formed on the entire second surface of the substrate, then surface recombination is effectively reduced, but the isolation between adjacent photovoltaic cells is insufficient, leading to increased optical loss
Solution Approach 1:
The second surface is divided into three distinct regions: first region (112a) with full passivation structure, second region (112b) with selective passivation, and isolation region (112c) with isolation structures. This segmentation allows different areas to serve different functions - the first region provides comprehensive surface passivation, while the isolation region prevents optical interference between adjacent cells, thereby resolving the contradiction between passivation quality and optical loss.
Solution Approach 2:
Different passivation structures are applied to different regions of the second surface. The first region receives a complete multi-layer passivation structure (tunnel oxide layers, intrinsic amorphous silicon layers, and doped layers), while the isolation region receives isolation structures that extend from the first surface through the substrate to the second surface. This local differentiation optimizes both passivation performance and optical isolation.
2Device complexity
If the substrate size is increased to reduce the number of cells per module, then module complexity is reduced, but the total optical loss increases due to more isolation structures
Solution Approach 1:
The isolation structures are localized to specific isolation regions (112c) between adjacent cells rather than covering the entire substrate. This localized approach provides necessary optical isolation between cells while minimizing the total area occupied by isolation structures, thereby reducing total optical loss even as substrate size increases and the number of cells per module changes.
3Reliability
If a multi-layer passivation structure with multiple doping steps is implemented, then surface passivation quality is improved, but the manufacturing process complexity increases
Solution Approach 1:
The manufacturing process is segmented into distinct steps corresponding to different regions: first forming the complete passivation structure on the first region, then selectively removing layers in the second region, and finally forming isolation structures in the isolation region. This segmented approach, while multi-step, provides clear process control and enables high-quality passivation through systematic fabrication sequences.
Solution Approach 2:
The tunnel oxide layers and intrinsic amorphous silicon layers are formed first as a preliminary passivation structure, followed by selective removal in the second region, and then doping steps are performed. This preliminary formation of the base passivation structure allows subsequent selective modifications without requiring complete re-fabrication, thereby managing process complexity while achieving high 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
This approach simplifies the manufacturing process, reduces costs, and enhances the efficiency and reliability of TBC solar cells by minimizing parasitic absorption and improving ohmic contact effects, facilitating mass production while maintaining high efficiency.
Implementation Method 1
doping the first intrinsic amorphous silicon layer (130) and the second intrinsic amorphous silicon layer (150) located in the first region (112a) with a first element, to obtain a first doped layer and a second doped layer respectively
Implementation Method 2
a first tunnel oxide layer (120)... and a second tunnel oxide layer (140)... to isolate the first tunnel oxide layer (120) located in the first region (112a) from the first tunnel oxide layer (120) located in the second region (112b)
Implementation Method 3
Solar cell and manufacturing method thereof, photovoltaic module, and photovoltaic system
Data Source
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AI summary
The present application relates to a solar cell and a manufacturing method thereof, a photovoltaic module, and a photovoltaic system. A manufacturing method for a solar cell includes providing a substrate (110), and dividing the second surface into a first region (112a), a second region (112b), and an isolation region (112c); sequentially stacking a first tunnel oxide layer (120), a first intrinsic amorphous silicon layer (130), a second tunnel oxide layer (140), and a second intrinsic amorphous silicon layer (150) on the second surface (112) of the substrate (110); removing the second intrinsic amorphous silicon layer (150) and the second tunnel oxide layer (140) located in the second region (112b); doping the first intrinsic amorphous silicon layer (130) and the second intrinsic amorphous silicon layer (150) located in the first region (112a) with a first element, to obtain a first doped layer and a second doped layer respectively; and doping the first intrinsic amorphous silicon layer (130) located in the second region (112b) with a second element, to obtain a third doped layer; and forming an isolation structure (190) in the isolation region, to isolate the first tunnel oxide layer (120) located in the first region (112a) from the first tunnel oxide layer (120) located in the second region (112b) and isolate the first doped layer and the second doped layer located in the first region from the third doped layer located in the second region.