Solar Cell Back Metallization With Nickel Contact and Thin Polysilicon
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high manufacturing cost of solar cells due to the use of silver paste and the resulting thick polysilicon layer, which increases parasitic light absorption and reduces efficiency, necessitates a cost-effective alternative for metallization that maintains passivation and light utilization efficiency.
Innovation Solution
A method involving the sequential formation of a tunnel silicon oxide layer, N-type doped polysilicon layer, and back passivated anti-reflection film on a silicon substrate, followed by grooving and forming a nickel metal layer, and printing aluminum and silver gate electrodes, which reduces polysilicon layer damage and parasitic light absorption while ensuring efficient metallization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver paste is used for metallization, then conductivity and solderability are improved, but manufacturing cost increases
Solution Approach 1:
The patent uses a composite metallization structure consisting of a nickel silicide layer combined with a metal paste layer (aluminum or silver). The nickel silicide provides stable ohmic contact and conductivity, while the metal paste layer provides solderability and additional conductivity. This composite approach achieves the electrical performance of silver paste but with lower cost materials.
Solution Approach 2:
The patent replaces expensive silver paste with cheaper alternatives such as aluminum paste or a combination of nickel silicide with thin metal layers. While silver has superior properties, the invention demonstrates that cheaper materials can achieve sufficient performance for commercial solar cells, reducing manufacturing cost while maintaining acceptable reliability.
2Ease of manufacture
If aluminum paste is used instead of silver paste to reduce cost, then manufacturing cost decreases, but the polysilicon layer is damaged at high temperature
Solution Approach 1:
The patent performs a preliminary low-temperature annealing step (700-900°C) to form the nickel silicide layer and establish stable ohmic contact before applying and firing the aluminum paste. This preliminary action creates a protective and conductive interface that prevents the aluminum paste from damaging the polysilicon layer during the subsequent high-temperature paste firing process.
Solution Approach 2:
The nickel silicide layer acts as an intermediary between the aluminum paste and the polysilicon layer. It provides a stable, heat-resistant interface that allows the aluminum paste to be fired at high temperatures without directly contacting and damaging the polysilicon layer, thus protecting the organic matter in the polysilicon while maintaining electrical conductivity.
3Reliability
If a thick polysilicon layer is used to prevent damage during metallization, then polysilicon layer integrity is improved, but parasitic light absorption increases and efficiency decreases
Solution Approach 1:
The patent performs preliminary low-temperature annealing to form nickel silicide and establish stable ohmic contact before applying aluminum paste. This preliminary action creates a protective interface that prevents damage during subsequent high-temperature processing, allowing the use of thinner polysilicon layers without risking integrity, thus reducing parasitic light absorption.
Solution Approach 2:
The patent changes the processing parameters by using low-temperature annealing (700-900°C) followed by controlled paste firing, rather than requiring high-temperature processing of thick polysilicon layers. This parameter change allows thin polysilicon layers to maintain integrity while minimizing light absorption losses.
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 reduces manufacturing costs, minimizes polysilicon layer damage, and enhances light utilization efficiency by using nickel and silver electrodes, thereby increasing the overall efficiency of solar cells.
Implementation Method 1
a silicon oxide layer is used to passivate a back surface of a silicon substrate
Implementation Method 2
it is generally required to corrode part of the silicon by the glass frit in the silver paste to form an ohmic contact
Implementation Method 3
printing a back fine gate electrode on the nickel metal layer, and printing a back main gate electrode on the back passivated anti-reflection film
Data Source
AI summary
The application discloses a solar cell and a preparation method for a solar cell. The preparation method for a solar cell comprises: sequentially forming a tunnel silicon oxide layer, an N-type doped polysilicon layer, and a back passivated anti-reflection film on a back surface of an N-type silicon substrate; performing grooving on the back passivated anti-reflection film, and forming a nickel metal layer in a grooved region; printing a back fine gate electrode on the nickel metal layer, and printing a back main gate electrode on the back passivated anti-reflection film, wherein the back fine gate electrode is electrically connected to the back main gate electrode.