Seeded Contact Structure for Low-Loss Passivated Solar Cells
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Solution Overview
Problem
Conventional solar cells face challenges with recombination losses due to direct metal contact with the silicon substrate, leading to reduced photoconversion efficiency, and require thick passivating layers that cause parasitic absorption, making them costly and inefficient.
Innovation Solution
A photovoltaic device with a non-fired-through electrical contact structure using a patterned metal seed layer, metal particle paste, and metallic plating layer, which eliminates the need for a TCO layer and allows for thin passivating layers, reducing parasitic losses and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver particle paste is fired-through at high temperature to form low resistivity contact, then contact resistivity is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The invention changes the temperature parameter from high-temperature firing (850°C) to low-temperature processing (around 200°C). The metallic plating layer is deposited at low temperature and provides low-resistance contact without requiring high-temperature firing, thus reducing contact resistivity while simplifying the manufacturing process and enabling integration with temperature-sensitive components.
2Reliability
If TCO layer is used for passivation and conduction, then selective conduction and passivation are achieved, but additional manufacturing steps and cost are required
Solution Approach 1:
The metallic plating layer performs multiple functions simultaneously: it provides low-resistance electrical contact, serves as a reflective layer to reduce optical losses, and enables integration with copper-based interconnection technologies. This multi-functionality reduces the need for separate TCO layers and other additional components, simplifying the overall manufacturing process while maintaining selective conduction and passivation properties.
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 solution achieves higher photoconversion efficiency by minimizing parasitic absorption and reducing the use of expensive materials like silver, while maintaining low resistivity and good adhesion, thus enhancing economic viability.
Implementation Method 1
a metallic plating layer, typically of copper, nickel, tin or alloys thereof, provided upon said TCO layer and said metal particle paste in said seeded zones and in electrical connection with said metal particle paste
Implementation Method 2
a patterned metal seed layer, typically applied by sputtering and comprising one or more of Ag, Al, Co, Cr, Mo, Ni, NiV, Ta, Ti, W, WTi, Cu, Ni and alloys thereof provided upon said passivating layer
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Photovoltaic device comprising: - a silicon-based substrate (1); - a tunneling layer (2) provided upon said silicon-based substrate (1); - a passivating layer (3) provided upon said tunneling layer (2); - an electrical contact structure (12, 5, 9) situated upon said passivating layer (3); - a dielectric layer (4) provided upon said passivating layer (3); According to the invention, said electrical contact structure (12, 5, 9) comprises: - a patterned metal seed layer (12) provided upon said passivating layer (3) and defining seeded zones (14); - a metal particle paste (5) provided exclusively upon said patterned metal seed layer (12) in said seeded zones (14), said dielectric layer (4) extending over said metal particle paste (5) discontinuously; and - a metallic plating layer (9) provided upon said dielectric layer (4) in said seeded zones (14) and in electrical connection with said metal particle paste (5).