Back-Contact Silicon Heterojunction Layout With Fewer Patterning Steps
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Solution Overview
Problem
The production of interdigitated back-contact silicon heterojunction solar cells is hindered by complex and costly processing techniques that require extensive photolithography and wet-etching, leading to lengthy and cost-ineffective manufacturing processes, with existing alternatives offering reduced efficiency due to the patterning of both electron- and hole-collecting structures.
Innovation Solution
A method involving a silicon-based substrate with a patterned first silicon layer and a microcrystalline second silicon layer, where the second silicon layer is deposited on the first silicon layer and an intrinsic buffer layer, forming a tunnel layer with unique properties that allow for efficient charge collection without impeding the operation, reducing the need for multiple patterning steps and enhancing device efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photovoltaic modules are manufactured with standard encapsulation processes, then manufacturing simplicity is maintained, but encapsulation resin cracks and delamination occur due to module deformation from heat and moisture
Solution Approach 1:
The patent implements a multi-layer encapsulation structure where an under-encapsulant layer is positioned between the photovoltaic cell and the main encapsulation resin. This nested configuration protects the cell surface from direct exposure to environmental stressors while maintaining structural integrity, preventing both cracks and delamination without significantly complicating the overall manufacturing process
Solution Approach 2:
The patent employs different materials with complementary properties for the under-encapsulant layer and the main encapsulation resin. The under-encapsulant layer uses materials with specific adhesion properties and flexibility to accommodate thermal expansion, while the outer resin provides environmental protection. This composite approach resolves the contradiction by combining materials that collectively prevent degradation while maintaining manufacturing feasibility
2Reliability
If photovoltaic cells are directly encapsulated without additional protective layers, then device complexity is reduced, but black spots and performance degradation occur due to direct contact between encapsulation resin and cell surface
Solution Approach 1:
The under-encapsulant layer is nested between the cell and the main encapsulation resin, creating a protective interface that prevents direct harmful contact while allowing the encapsulation structure to function. This layer acts as a buffer that eliminates black spot formation and performance degradation without requiring complete redesign of the encapsulation system
Solution Approach 2:
The under-encapsulant layer serves as an intermediary substance that mediates the interaction between the photovoltaic cell and the encapsulation resin. It provides a protective barrier that prevents direct adverse contact while maintaining the encapsulation's primary functions of protection and structural support, thereby improving reliability without excessive complexity
3Strength
If high-temperature lamination is used for encapsulation, then bonding strength is improved, but module deformation and resin cracking occur due to thermal stress
Solution Approach 1:
The patent modifies the lamination process parameters by implementing a two-stage temperature approach: initial lamination at a lower temperature to establish basic bonding, followed by a controlled second lamination at higher temperature to enhance adhesion. This parameter adjustment achieves strong bonding while preventing thermal stress-induced deformation and cracking that would occur with single-stage high-temperature processing
4Manufacturing precision
If multiple lamination processes are performed to improve encapsulation quality, then encapsulation quality is enhanced, but manufacturing time and complexity increase
Solution Approach 1:
The under-encapsulant layer is applied in advance before the main encapsulation resin is introduced. This preliminary action creates a prepared surface that facilitates subsequent encapsulation processes, ensuring proper adhesion and preventing defects. By performing this preparatory step beforehand, the patent achieves high encapsulation quality without requiring excessive post-processing or repeated lamination cycles, thus maintaining manufacturing 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 approach simplifies the manufacturing process by reducing the number of patterning steps, improves charge collection efficiency, and results in a cost-effective and efficient photovoltaic device with elevated performance compared to prior art, while maintaining similar efficiencies for both charge collecting structures.
Implementation Method 1
a photovoltaic cell for converting solar energy into electrical energy
Data Source
Figure 1~2
Figure 3
Figure 4a~4d
AI summary
A photovoltaic device is proposed comprising a silicon-based substrate (2) having a p-type or n-type doping, with an intrinsic buffer layer (4) situated on said substrate. A first silicon layer (6) of a first doping type is situated on predetermined regions (4a) of the intrinsic buffer layer. The first layer has interstices (5) between said predetermined regions (4a). The first silicon layer comprises at least partially a microcrystalline layer at its side away from the substrate. A microcrystalline silicon layer (8) of a second doping type is situated on said first silicon layer (6). A third silicon layer (10) of the second doping type is situated on said intrinsic buffer layer at the interstices, the third silicon layer being amorphous at its side facing said silicon- based substrate and comprising an at least partially microcrystalline layer portion to the side away from the intrinsic buffer layer.