Solar Cell Electrode Shape Accuracy via Segmented Conductive Paste
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing solar cell electrodes lack high shape accuracy, which affects their performance and efficiency due to difficulties in applying conductive pastes with high aspect ratio materials over textured surfaces.
Innovation Solution
The use of a conductive paste comprising first and second conductive materials with a higher volume fraction of flat-shaped second conductive materials, where the aspect ratio of second conductive materials is greater than that of first conductive materials, applied to a photoelectric conversion body with rugged structures, allowing for improved electrode formation and shape accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional conductive paste with uniform particle size is applied to textured surfaces, then the paste can be applied easily, but the electrode shape accuracy deteriorates
Solution Approach 1:
The conductive paste is segmented into two distinct particle size groups: first conductive materials with smaller particle size (0.5-2.0 μm) that can penetrate and fill the textured surface structures, and second conductive materials with larger particle size (3.0-10.0 μm) that form the bulk electrode structure. This segmentation allows each particle size to perform its specific function optimally, resolving the contradiction between filling capability and shape accuracy.
Solution Approach 2:
Different regions of the electrode are formed by different particle sizes: the smaller first conductive materials locally fill the textured surface structures to achieve good contact, while the larger second conductive materials form the upper electrode structure with high shape accuracy. This local differentiation of material properties resolves the contradiction between surface filling and overall shape precision.
2Manufacturing precision
If high aspect ratio conductive materials are used to improve electrode shape, then shape accuracy improves, but the paste becomes difficult to apply over textured surfaces
Solution Approach 1:
The conductive materials are segmented into two populations with different aspect ratios: first conductive materials with lower aspect ratio that can easily flow into and fill the textured surface, and second conductive materials with high aspect ratio (greater than 5:1) that provide vertical structure and shape accuracy. This segmentation allows the paste to be applied easily while still achieving high shape accuracy in the final electrode.
Solution Approach 2:
The conductive paste is formulated as a composite material containing both spherical/irregular first conductive particles and high aspect ratio second conductive particles (such as flake or rod-shaped particles). This composite structure combines the flowability and filling capability of low aspect ratio particles with the shape-defining capability of high aspect ratio particles, resolving the contradiction between ease of application and shape accuracy.
3Reliability
If conductive paste is applied to fill textured structures, then contact resistance decreases, but electrode shape accuracy deteriorates
Solution Approach 1:
The electrode is segmented into two functional zones: the lower zone filled with smaller first conductive materials that penetrate and fill the textured surface structures to minimize contact resistance, and the upper zone formed by larger second conductive materials that define the electrode's external shape and pattern accuracy. This segmentation allows both low contact resistance and high shape accuracy to be achieved simultaneously.
Solution Approach 2:
Different particle size qualities are applied locally: smaller particles are concentrated in the regions requiring good electrical contact with the textured surface, while larger particles are concentrated in the regions requiring precise shape definition. This local quality differentiation resolves the contradiction between contact resistance and shape accuracy.
Data Source
Figure 1~2
Figure 3~4
AI summary
A solar cell includes a photoelectric conversion body having principal surface with rugged structures and an electrode on the principal surface. The electrode includes first conductive materials, second conductive materials and resin. The second conductive materials are flat-shaped so that an aspect ratio of the second conductive materials, which is a ratio of a major axis diameters to their average thickness (the major axis diameter divided by the average thickness) , is larger than that of the first conductive materials. In the electrode, a volume fraction of the second conductive materials is larger than that of the first conductive materials. The rugged structures include rugged structures which are larger than an average particle size of the first conductive materials, but smaller than an average major axis diameter of the second conductive materials.