Solar Cell Local TOPCon Contacts Without Electrode Alignment
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Solution Overview
Problem
The application of TOPCon technology on the front surface of solar cells leads to excessive light absorption by the polysilicon film, reducing light absorption in the crystalline silicon substrate, and the preparation of local passivated contact/emitter structures is difficult due to alignment issues in the screen printing process.
Innovation Solution
A method involving the formation of a tunnel silicon oxide layer and an N-type doped polysilicon layer on the front surface of a P-type silicon substrate, followed by electroplating and light irradiation to grow a metal electrode on the polysilicon layer without the need for alignment, using a light-induced electroplating method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If screen printing technology is used to prepare the front metal electrode, then the metal electrode can be formed on the polysilicon layer, but alignment precision with the local tunnel oxide passivated layer and polysilicon layer is difficult to achieve
Solution Approach 1:
The patent replaces the mechanical screen printing process with a chemical electroplating process. Instead of using mechanical screen printing to deposit metal, the invention uses electroplating where metal ions are deposited onto the polysilicon layer through electrochemical reactions, eliminating the alignment requirements inherent in mechanical positioning methods.
Solution Approach 2:
The patent changes the deposition mechanism from mechanical (screen printing) to electrochemical (electroplating). By controlling parameters such as electroplating time, current density, and electrolyte composition, the metal electrode width is precisely controlled to match the polysilicon layer width without requiring mechanical alignment.
2Reliability
If TOPCon is applied to the front surface of the solar cell, then the passivated contact structure can be formed, but light absorption by the polysilicon film increases excessively, reducing light absorption by the crystalline silicon substrate
Solution Approach 1:
The patent applies the tunnel oxide passivated contact structure locally only in the regions where metal electrodes are needed, rather than across the entire front surface. This localized application minimizes the total polysilicon area that could cause parasitic absorption while maintaining the necessary passivation and electrical contact functions.
Solution Approach 2:
The patent uses a thin polysilicon layer (100-200 nm) that provides sufficient passivation and electrical contact properties without excessive thickness that would cause parasitic absorption. The partial coverage approach ensures adequate functionality while minimizing light absorption losses in the crystalline silicon substrate.
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 simplifies the preparation process, reduces alignment difficulties, and enhances the efficiency of the solar cell by maintaining the width of the metal electrode consistent with the polysilicon layer, thereby increasing open circuit voltage, short-circuit current, and fill factor.
Implementation Method 1
irradiating the front surface of the P-type silicon substrate with light for a set duration so as to grow a front metal electrode on the N-type doped polysilicon layer
Data Source
AI summary
The present disclosure discloses a preparation method for a solar cell and a solar cell. The preparation method for a solar cell comprises: locally forming a tunnel silicon oxide layer and an N-type doped polysilicon layer on a front surface of a P-type silicon substrate, wherein the N-type doped polysilicon layer is stacked on the tunnel silicon oxide layer; immersing the P-type silicon substrate having the tunnel silicon oxide layer and the N-type doped polysilicon layer locally formed on the front surface into an electroplating solution, irradiating the front surface of the P-type silicon substrate with light for a set duration so as to grow a front metal electrode on the N-type doped polysilicon layer, and removing a metal remaining on the front surface of the P-type silicon substrate by etching, wherein the width of the front metal electrode is the same as the width of the N-type doped polysilicon layer. The preparation method may omit an alignment operation in a metal electrode preparation process, thereby effectively reducing a difficulty in a preparation process of a local passivated contact emitter.