Bifacial TOPCON Solar Cell Texturing for Mask-Free Localized Emitters
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Solution Overview
Problem
Existing TOPCON cells face challenges in improving their bifaciality factor and efficiency while also facing high production costs and the need for precise process control.
Innovation Solution
A method involving multiple stages of double-sided texturing and diffusion processes, including boron and phosphorus diffusion, laser grooving, and selective emitter formation, which omits costly mask and alkali polishing steps, enhances passivation, and improves light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional mask and alkali polishing steps are used in TOPCON cell manufacturing, then manufacturing precision can be maintained, but production costs increase and process complexity increases
Solution Approach 1:
The patent removes the mask and alkali polishing steps from the traditional manufacturing process. By using laser grooving to directly form localized emitters on the textured surface, the process eliminates costly and complex mask alignment and polishing operations while maintaining precise emitter formation through laser-controlled material removal and in-situ doping
Solution Approach 2:
The patent replaces mechanical mask alignment and polishing systems with a laser-based system. The laser grooving process uses optical fields to precisely define emitter locations and shapes, substituting mechanical positioning and material removal methods with optical processing that achieves higher precision at lower cost
2Productivity
If multiple diffusion layers and texturing steps are added to improve bifaciality factor, then cell efficiency improves, but process complexity increases
Solution Approach 1:
The patent combines multiple functions into integrated steps. The laser grooving process simultaneously creates the emitter structure, defines the doping region, and forms the contact pattern in a single operation. The texturing and diffusion processes are integrated to create passivated contacts that provide both surface passivation and selective carrier contact, reducing the number of separate process steps
Solution Approach 2:
The patent employs materials and processes that perform multiple functions. The phosphorus diffused layer serves as both the emitter contact and the passivation layer. The textured surface structure simultaneously enhances light absorption, facilitates diffusion, and provides mechanical support. This multi-functionality reduces process complexity while maintaining high cell efficiency
3Ease of manufacture
If laser grooving is used to form localized emitter, then mask process can be eliminated saving costs, but precise control of laser parameters is required
Solution Approach 1:
The patent optimizes laser parameters to achieve effective grooving with standard equipment. By controlling pulse duration, energy density, and scanning speed within specific ranges, the process achieves precise emitter formation without requiring exotic laser systems. The parameters are tuned to match the absorption characteristics of the textured silicon surface, enabling controlled material removal and in-situ doping
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
The method significantly improves the bifaciality factor, open-circuit voltage, and reduces production costs by optimizing the textured surface structure and eliminating the need for masks, thereby enhancing the overall efficiency of TOPCON cells.
Implementation Method 1
first double-sided texturing the silicon wafer to form first textured surfaces on the front side and the back side
Implementation Method 2
performing boron diffusion on the back side to form a boron diffused layer
Implementation Method 3
performing phosphorus diffusion to form a doped polysilicon layer and a phosphorosilicate glass, or directly performing phosphorus diffusion on the front side to form a phosphorus diffused layer
Implementation Method 4
laser grooving to form a localized emitter
Implementation Method 5
depositing polysilicon on the front side
Data Source
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AI summary
The present application provides a method for preparing a bifacial TOPCON cell and a bifacial TOPCON cell. The preparation method includes steps of double-sided texturing the silicon wafer multiple times (S1, S3, S7 or S1, S3, S9). Polysilicon (5) is deposited on the front side, and then phosphorus diffusion is performed to form a doped polysilicon layer (7) and a phosphosilicate glass (6); alternatively, the phosphorus diffusion is performed to form the phosphorus diffused layer (13) and the phosphosilicate glass (6'). Laser grooving is performed to form localized emitters (S6). After third double-sided texturing on the silicon wafer (S7, S9), the double-sided rounding is performed.