Solar Cell Back Contact Structure Using Passivation Layer
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Solution Overview
Problem
The high cost and complexity of manufacturing solar cells, particularly due to expensive materials and additional processing steps required for efficient energy conversion, hinder the widespread adoption of cost-effective and high-volume production methods.
Innovation Solution
A material structure for solar cells is developed, where electrical contacts are formed using a first metal (molybdenum) with low resistivity and good adhesion, and a second metal (such as copper) for improved reflectivity, combined with a passivation layer to reduce recombination losses, allowing for efficient charge transfer and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a back side metal contact is used to provide efficient contacting to the light absorbing layer, then electrical contact efficiency is improved, but charge carrier capture and light absorption by the metal contact increase, reducing solar cell efficiency
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the metal contact and the light absorbing layer. This dielectric layer allows electrical contact while preventing charge carrier capture and reducing light absorption by the metal, thereby resolving the contradiction between contact efficiency and energy loss
Solution Approach 2:
The contact structure is segmented into multiple functional layers: a metal contact layer for electrical conduction, a dielectric layer for protection and optical management, and selective contact regions. This segmentation allows each layer to perform its specific function optimally without interfering with others
2Loss of energy
If crystalline silicon wafers with monocrystalline or multi-crystalline silicon light absorbing layers are used, then high conversion efficiency is achieved, but manufacturing cost increases and brittleness occurs
Solution Approach 1:
The invention changes the material parameters by using thin-film semiconductor layers deposited on flexible substrates instead of thick crystalline silicon wafers. This parameter change maintains optical absorption efficiency while dramatically reducing material cost and eliminating brittleness
Solution Approach 2:
The solar cell structure uses composite materials including thin-film semiconductor layers, dielectric layers, and flexible substrates. This composite approach combines the advantages of different materials to achieve high efficiency, low cost, and flexibility simultaneously
3Loss of energy
If a passivation layer with openings is used to mitigate charge carrier capture by the metal layer, then solar cell efficiency is improved, but manufacturing complexity and cost increase due to extra processing steps
Solution Approach 1:
The dielectric layer serves multiple functions simultaneously: it provides passivation to prevent charge carrier recombination, acts as an optical management layer to reduce metal absorption, and enables flexible contact patterns. This multi-functionality reduces the need for separate processing 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
This approach reduces material costs, enhances solar cell efficiency by increasing light absorption, and improves thermal management, resulting in a more cost-effective and scalable production process while maintaining high performance.
Implementation Method 1
A conventional solar cell comprises a light absorbing layer arranged to absorb photons and to convert the energy of the photons into free charge carriers
Implementation Method 2
The metal layer may be formed by a second metal, wherein the second metal is different from the first metal... providing an improved reflectivity as compared to the material of the electrical contacts
Data Source
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AI summary
The present invention relates to a material structure for a solar cell and a method for manufacturing the material structure. A solar cell comprising the material structure is also disclosed. The material structure (100) comprising, a light absorbing layer (102) being a semiconductor material, a metal layer (104), a passivation layer (106) arranged in between the light absorbing layer (102) and the metal layer (104), the passivation layer (106) comprising a plurality of electrical contacts (108), the electrical contacts (108) extending from a top surface (110) to a bottom surface (112) of the passivation layer (106) such that the electrical contacts (108) are in galvanic contact with the light absorbing layer (102) and the metal layer (104), wherein the electrical contacts (108) are formed by a first metal and the metal layer (104) is formed by a second metal, the second metal being different from the first metal.