CIGS Solar Cell CVD Deposition Gradient
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Solution Overview
Problem
The high cost and complex manufacturing processes associated with monocrystalline silicon solar cells, as well as the limitations in reducing the manufacturing cost of polycrystalline silicon solar cells due to increasing silicon prices, necessitate the development of more economical and efficient alternatives for solar energy conversion.
Innovation Solution
A method for manufacturing solar cells using a CIGS light absorbing layer, where a copper precursor is deposited as a thin film followed by gallium and indium-selenium thin films using chemical vapor deposition, with sequential formation of a buffer and front electrode layer, resulting in a selenium deficit at the lower surface and copper deficit at the upper surface of the CIGS layer, minimizing the MoSex layer formation and optimizing the band gap energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monocrystalline silicon is used for solar cell manufacturing, then photoelectric conversion efficiency is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent replaces expensive monocrystalline silicon with a cheaper thin-film structure using CIGS absorber layer deposited on glass substrate. The thin-film solar cell uses significantly less semiconductor material while achieving competitive efficiency through optimized layer structure and composition gradients.
Solution Approach 2:
The patent employs a composite thin-film structure consisting of multiple layers including CIGS absorber, buffer layers, and transport layers. This composite approach combines materials with complementary properties to achieve high photoelectric conversion efficiency while maintaining manufacturing simplicity and low cost.
2Ease of manufacture
If polycrystalline silicon is used to reduce manufacturing cost, then cost decreases, but manufacturing process remains complicated and cost reduction is limited by silicon price increase
Solution Approach 1:
The patent uses inexpensive thin-film materials deposited in thin layers rather than bulk silicon wafers. The CIGS absorber layer is only a few micrometers thick, requiring minimal raw materials and enabling cost-effective manufacturing through simple deposition processes.
Solution Approach 2:
The patent extracts the essential light-absorbing function from thick silicon wafers and concentrates it in a thin CIGS film layer. This extraction allows the solar cell to achieve sufficient light absorption with minimal material, dramatically reducing raw material costs while simplifying the manufacturing process.
3Ease of manufacture
If conventional CIGS deposition is used, then manufacturing is simple, but MoSex layer formation increases and photoelectric conversion efficiency is reduced
Solution Approach 1:
The patent applies local quality control by creating a composition gradient within the CIGS absorber layer. The composition is optimized at different depths: Cu-poor at the front interface to reduce MoSex formation, and Cu-rich at the back interface to improve carrier collection. This spatial variation in composition simultaneously addresses both manufacturing simplicity and efficiency requirements.
Solution Approach 2:
The patent changes the compositional parameters of the CIGS layer during deposition, transitioning from Cu-poor to Cu-rich composition through the layer depth. This parameter change allows optimization of the front interface to minimize harmful MoSex formation while maintaining good photoelectric properties throughout the absorber layer.
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 the formation of the MoSex layer, enhances the solar cell performance by controlling the band gap energy, and improves the photoelectric conversion efficiency while maintaining a low porosity and large average crystal grain size in the CIGS light absorbing layer.
Implementation Method 1
supplying a copper precursor to deposit a copper thin film using chemical vapor deposition
Implementation Method 2
supplying a gallium precursor to deposit a gallium thin film using chemical vapor deposition
Implementation Method 3
supplying an indium precursor and a first selenium precursor to deposit an indium-selenium thin film using chemical vapor deposition
Data Source
AI summary
The resent invention relates to a method for manufacturing a solar cell, the method comprising the steps of: (a) forming a lower electrode layer on a substrate; (b) forming a CIGS light absorbing layer on the lower electrode layer by supplying a copper precursor to deposit a copper thin film using chemical vapor deposition and then supplying a gallium precursor, an indium precursor, and a first selenium precursor to deposit a gallium thin film and an indium-selenium thin film using chemical vapor deposition; and (c) sequentially forming a buffer layer and a front electrode layer on the CIGS light absorbing layer.