Thin Film Solar Cell Trench Interconnection Alignment
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Solution Overview
Problem
Existing methods for manufacturing thin film solar cells result in significant non-photovoltaic active area shading due to inaccurate alignment of insulating and conductive ink patterns, leading to reduced efficiency and production yield.
Innovation Solution
A method combining additive and subtractive processes, specifically using inkjet printing and laser ablation, to create a structured trench system that allows for improved alignment and reduced dead zones by defining conductive connections through the position of trenches rather than inkjet line dimensions, enabling serial interconnection of adjacent cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If insulating ink and conductive ink are applied using inkjet printing defined by line dimensions, then the manufacturing process is simple, but the alignment accuracy between via scribe and isolation scribes is insufficient, creating dead zones that reduce efficiency
Solution Approach 1:
The patent segments the interconnection structure into four distinct trenches: first trench for cell isolation, second trench for partial isolation, third trench for bottom electrode contact, and fourth trench for top electrode contact. This segmentation allows each trench to be precisely positioned and filled independently, achieving high alignment accuracy without requiring complex inkjet printing processes.
Solution Approach 2:
The patent creates all four trenches and fills them with appropriate materials (insulating material for first and second trenches, conductive material for third and fourth trenches) before final assembly. This preliminary action ensures that alignment is determined by the fixed trench positions rather than by inkjet line dimensions, eliminating dead zones and improving efficiency.
2Productivity
If the conductive ink area is disposed to form via between adjacent cells, then cell interconnection is achieved, but the alignment must be sufficiently accurate which reduces production yield
Solution Approach 1:
The patent designs the trench structure so that the conductive material automatically fills the third and fourth trenches to the appropriate levels, creating self-aligned via structures. The bridge element of conductive material spans between trenches, ensuring reliable electrical connection without requiring high-precision alignment during assembly, thereby improving production yield.
3Reliability
If the first and second trenches are filled with insulating material, then cell isolation is achieved, but the alignment of subsequent conductive structures becomes more difficult
Solution Approach 1:
The patent applies different materials to different locations: insulating material is placed only in the first and second trenches where cell isolation is needed, while the third and fourth trenches receive conductive material for electrical connection. The bridge element is positioned locally to span between trenches. This localized material placement achieves reliable cell isolation while maintaining ease of manufacture for conductive structures.
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 enhances the alignment accuracy and reduces non-photovoltaic active area, improving the production yield and module quality by minimizing dead zones and optimizing the interconnection process.
Implementation Method 1
creating a first trench in the insulating layer and the layer stack that extends to the surface of the substrate; creating at a first side of the first trench, a second trench in the insulating layer and the layer stack
Implementation Method 2
a photovoltaic active layer, and a top electrode layer... the photovoltaic active layer arranged on the bottom electrode layer
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
AI summary
Solar cell arrangement of a thin film solar cell array on a substrate (5); each solar cell being layered with a bottom electrode (6), a photovoltaic active layer (7), a top electrode (8) and an insulating layer (9). A first trench (10A) and a second trench (11A) parallel to the first trench at a first side, separate a first solar cell and an adjacent second solar cell. The first and second trenches are filled with insulating material. The first trench extends to the substrate. The second trench extends into the photovoltaic active layer below the top electrode. A third trench (12) extending to the bottom electrode is between the first and second trench. A fourth trench (13) extending to the top electrode is at a second side of the first trench. The third and fourth trench are filled with conductive material. A conductive bridge (16) connects the third trench and the fourth trench across the first trench.