Solar Cell Through Holes Reduce Contact Resistance
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Solution Overview
Problem
Existing solar cells face challenges in manufacturing efficiency and photo-electric conversion efficiency due to high contact resistance and dead zones created during the patterning process of connecting unit cells in series.
Innovation Solution
A solar cell design featuring a back electrode layer with first through holes, a light absorbing layer with second through holes, a front electrode layer, and a first conductive layer formed on the front electrode layer corresponding to the second through holes, which reduces contact resistance by facilitating electron transfer through the first conductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a typical thin film solar cell module structure with divided unit cells is used, then the solar cell can be manufactured with standard patterning processes, but dead zones are produced during the patterning process which increase contact resistance and reduce photo-electric conversion efficiency
Solution Approach 1:
A conductive paste layer is introduced as an intermediary element between the divided unit cells. This conductive paste layer is formed in the dead zone regions and serves as a mediator to transfer electrons between adjacent solar cell units, thereby reducing contact resistance without requiring changes to the fundamental divided cell structure or patterning processes.
Solution Approach 2:
The electrical conductivity parameter of the dead zone region is changed by forming a conductive paste layer in these regions. This transforms the previously insulating or high-resistance dead zones into conductive pathways, enabling efficient electron transfer between unit cells while maintaining the standard divided cell architecture.
2Reliability
If unit cells are connected in series through standard patterning, then electrical connection between cells is achieved, but contact resistance increases due to dead zone formation
Solution Approach 1:
The conductive paste layer acts as an intermediary substance that bridges the electrical connection between adjacent unit cells. It is specifically positioned in the dead zone regions where conventional interconnections fail, providing a low-resistance pathway for electron flow and eliminating the harmful contact resistance effect.
Solution Approach 2:
The harmful dead zone regions are extracted and repurposed. Instead of leaving these regions as non-functional gaps or high-resistance barriers, the conductive paste layer is selectively formed in these exact regions, converting the harmful dead zones into beneficial conductive interconnection zones.
3Reliability
If through holes are formed in the back electrode layer and light absorbing layer, then direct connection pathways are created, but the structure complexity increases
Solution Approach 1:
The electrical connection pathway is segmented into two functional parts: through holes formed in the back electrode layer and light absorbing layer, and the conductive paste layer filling these through holes. This segmentation allows each component to perform its specific function - the through holes provide the physical pathway, while the conductive paste provides the electrical conductivity, achieving low contact resistance through a modular approach.
Solution Approach 2:
The through holes are formed in advance during the layer formation process, before the conductive paste layer is applied. This preliminary action of creating the through holes ensures that the subsequent conductive paste application can directly fill the predefined pathways, simplifying the overall manufacturing sequence and reducing the need for additional complex alignment steps.
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
The solar cell design improves photo-electric conversion efficiency by reducing contact resistance and connection resistance between solar cells, thereby enhancing electrical conductivity and series resistance characteristics.
Implementation Method 1
electrons generated by the light are transferred through the first conductive layer, thereby reducing the contact resistance of the solar cell
Data Source
AI summary
A solar cell includes a back electrode layer provided on a support substrate and including a first through hole, a light absorbing layer provided on the first through hole and the back electrode layer and including a second through hole, a front electrode layer provided on the second through hole and the light absorbing layer, and a first conductive layer provided on the front electrode layer. Furthermore, the first conductive layer is formed on at least a portion of the front electrode layer which corresponds to the second through hole.