Solar Cell Paste Etching Mask for Selective Emitter Formation
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Solution Overview
Problem
Conventional methods for forming a selective emitter layer in solar cells face issues with process reproducibility and stability, leading to decreased conversion efficiency due to excessive doping and complex manufacturing processes.
Innovation Solution
A method involving the use of a paste with inorganic powder, organic solvent, and binder for forming an etching mask pattern, followed by selective wet etching with a HNO3, HF, CH3COOH, and H2O mixture, which allows for stable and reproducible etching back of the emitter layer, reducing the need for photolithography and high-temperature furnaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography and high-temperature furnace processes are used to form a selective emitter layer, then the emitter layer can be formed with controlled doping, but the manufacturing process becomes complex and costly
Solution Approach 1:
The patent extracts and eliminates the photolithography step from the conventional manufacturing process. Instead of using photoresist patterns and high-temperature furnace doping, the invention uses a paste-based etching mask that can be directly applied and patterned at lower temperatures, thereby simplifying the overall manufacturing process while maintaining emitter layer formation capability
Solution Approach 2:
The patent changes the temperature parameter from high-temperature furnace processing (typically >900°C) to low-temperature paste processing (<400°C). This parameter change enables the use of simpler equipment and processes while achieving the same functional result of forming a selective emitter layer with controlled doping characteristics
2Reliability
If emitter etch-back process is used to remove dead layer, then carrier mobility improves, but process reproducibility and stability decrease
Solution Approach 1:
The patent applies preliminary action by forming the etching mask pattern before the doping process. This mask pattern pre-defines the regions where doping will occur, eliminating the need for subsequent etch-back processes to remove dead layers. The mask is applied in advance and guides the doping process to achieve the desired selective emitter structure in a single step, improving process reproducibility and stability
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 stability and reproducibility of the emitter layer formation, improving the solar cell's conversion efficiency by maintaining optimal impurity distribution and contact characteristics.
Implementation Method 1
forming an etching mask pattern at a front electrode connection area on the emitter layer using a paste comprising inorganic powder
Implementation Method 2
etching back the emitter layer using the etching mask pattern as a mask
Data Source
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AI summary
Disclosed are a paste and a method for manufacturing a solar cell through screen printing said paste. The paste contains inorganic powder; an organic solvent; and a binder, and the inorganic powder has a tap density of 0.01 to 20 g/cm3. An etching mask pattern formed using said paste has good etch resistance in an etch-back process by which a selective emitter is formed, and thus, a stable emitter can be formed.