Electrodeposition on Textured Silicon Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in producing photovoltaic cells with textured surfaces is achieving reliable electrical contact between metallic patterns and the substrate without damaging the texture, as existing methods like screen printing often result in unsatisfactory contact due to the relief of the surface, leading to high electrical resistance and low adhesion issues.
Innovation Solution
A method involving electrodeposition of conductive materials, such as indium tin oxide or metals like copper, onto a textured silicon substrate, followed by an annealing step to improve contact quality and reduce resistivity, while using a printable material like Spin On Glass to create patterns that conform to the substrate's shape without damaging the texture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If screen printing is used to apply metallic paste on textured surface, then the process is simple and low-cost, but the electrical contact quality deteriorates due to poor adhesion and high resistance
Solution Approach 1:
The patent changes the deposition method from screen printing to electrodeposition, and modifies the substrate surface by filling valleys with oxide material. This transforms the textured surface into a hybrid structure that maintains optical benefits while providing smooth contact areas for metal deposition, thereby improving electrical contact quality without sacrificing manufacturing simplicity
Solution Approach 2:
The patent introduces an intermediary oxide material that fills the valleys of the textured surface. This intermediary layer acts as a bridge between the rough textured surface and the metallic paste, providing a smooth adhesive interface that ensures good electrical contact while preserving the underlying texture for optical performance
2Reliability
If annealing is performed at high temperature to improve contact, then electrical contact quality improves, but fragile materials like amorphous silicon are damaged
Solution Approach 1:
The patent changes the annealing temperature from high (400°C or above) to low (below 400°C), making the process compatible with fragile amorphous silicon layers. Combined with the oxide filling technique, this low-temperature annealing achieves good electrical contact without damaging temperature-sensitive materials
Solution Approach 2:
The patent performs oxide filling and low-temperature annealing before final metal deposition. This preliminary preparation creates optimal contact conditions that reduce or eliminate the need for high-temperature annealing later, protecting fragile materials from thermal damage
3Ease of manufacture
If conventional screen printing is used, then manufacturing is simple, but pattern width cannot be reduced below certain limit, causing excessive shading
Solution Approach 1:
The patent replaces the mechanical screen printing process with electrodeposition. This substitution enables precise control of metal deposition patterns, allowing for much narrower metal lines and reduced shading while maintaining manufacturing simplicity through automated electrochemical processes
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 enhances the quality of electrical contact, allows for the production of narrower patterns, reduces substrate shading, and increases the efficiency of photovoltaic devices by using better-conducting materials and maintaining the substrate's texturing, thereby improving overall device performance.
Implementation Method 1
A method involves electrodeposition of conductive materials, such as indium tin oxide or metals like copper, onto a textured silicon substrate
Implementation Method 2
followed by an annealing step to improve contact quality and reduce resistivity
Data Source
Figure 1a~1d
Figure 1e~1h
Figure 2
AI summary
The present invention relates to a method for creating electrically conducting or semiconducting patterns on a textured surface comprising a plurality of reliefs (102) of an amplitude greater than or equal 100 nanometres, characterized in that it comprises the following steps: - a step (10) of preparing a substrate (100, 110) during which step at least the textured surface of the substrate is rendered electrically conducting; - a coating step (20) during which at least one coat of an imprintable material (120) is laid on the textured surface, rendered electrically conducting, of the substrate; - a step (30) of pressing a mould (130) comprising hollows or projections in order to transfer the hollows or the projections of the mould (130) into the imprintable material (120) in order to form patterns (132); - a step (40) of withdrawing the mould leaving in place in the imprintable material (120) the imprint of the patterns (132); - a step of baring (50), at the bottom of the patterns, some of the textured surface, rendered electrically conducting, of the substrate; - a step (60) of electrically depositing an electrically conducting or semiconducting material in the patterns (132) to form conducting or semiconducting patterns (140, 150).