Local Back Contact Solar Cell Nanoscale Texturing
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Solution Overview
Problem
The existing process for producing passivated emitter rear contact (PERC) solar cells is costly and has low photoelectric conversion efficiency due to multiple steps and compromise of passivation effects during high-temperature sintering, necessitating a more efficient and cost-effective method.
Innovation Solution
A process combining the removal of damaged layers and double-sided polishing into a single step, employing a catalytic metal corrosion approach for nanometer-level texturing, which reduces production costs and improves the smoothness of the PN junction, increasing open circuit voltage and fill factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conventional PERC solar cell preparation process is used with multiple steps including back polishing and separate damaged layer removal, then the photoelectric conversion efficiency can be maintained, but the production cost increases and the process complexity increases
Solution Approach 1:
The patent combines the damaged layer removal step and the back polishing step into a single integrated process step. The chemical solution simultaneously performs both functions: removing damaged layers from the silicon wafer surface and polishing the back surface to create the textured structure. This merging eliminates the need for separate processing steps, reducing process complexity while maintaining the required manufacturing precision for efficient solar cell production.
Solution Approach 2:
The chemical solution used in the integrated step serves multiple functions simultaneously: it acts as a damaged layer remover, a polishing agent, and a texturing agent. This multi-functionality allows a single process step to achieve what previously required multiple separate steps, thereby simplifying the overall manufacturing process while maintaining the quality requirements for photoelectric conversion efficiency.
2Reliability
If the conventional PERC solar cell preparation process is used with multiple steps, then the passivation effect can be maintained, but the production cost increases
Solution Approach 1:
The patent merges damaged layer removal and back polishing into one step, reducing the total number of process steps. This consolidation lowers production costs by reducing equipment usage, chemical consumption, and processing time, while the integrated process is designed to maintain the necessary surface quality for effective passivation in subsequent processing steps.
Solution Approach 2:
The patent employs specific parameter optimization in the integrated step, including controlling solution concentration, temperature, and processing time, to achieve both damaged layer removal and adequate back surface polishing. By optimizing these parameters, the process maintains surface quality suitable for passivation while reducing overall production costs through step consolidation.
3Use of energy by moving object
If the nanometer-level textured structure is created through catalytic metal corrosion, then the surface reflectivity is reduced and optical absorption is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent integrates the texturing function into the same chemical solution process that removes damaged layers and polishes the back surface. The catalytic metal corrosion mechanism is incorporated into this multi-functional step, allowing the creation of nanometer-level textured structures without adding a separate texturing process. This merging reduces overall process complexity while achieving improved optical absorption through reduced surface reflectivity.
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 production process, reduces costs, and enhances the efficiency of polycrystalline silicon PERC solar cells by 0.47%, improving open circuit voltage and fill factor while achieving full band optical absorption.
Implementation Method 1
the texturing step employs a catalytic metal corrosion approach, and the textured structure is a nanometer-level textured structure
Implementation Method 2
Their power generation mechanism is based on the photovoltaic effect of semiconductor PN junction
Implementation Method 3
removing the damaged layer on the surface of a silicon wafer by immersing the silicon wafer in a mixture of 40% HF: 68% HNO3 at 5°C and during 3.5 minutes
Data Source
AI summary
A preparation method for a local back contact solar cell comprises the following steps: removing a damaged layer of a surface of a silicon wafer and carrying out double-sided polishing, texturing, forming a junction P-N, etching and removing impurity glass, depositing a passivation film on the back, depositing a passivation antireflection layer on the front, forming an opening in the local part of the back, coating the front and the back with metal slurry by means of silk-screen printing, and sintering; and in the step of texturing, a metal catalysis corrosion process is adopted, and a textured structure of the solar cell is a nanoscale textured structure. The processes of removing a damaged layer of a surface of a silicon wafer and double-sided polishing are combined into one working procedure, such that a technological process is simplified, and the cost is lowered.