Rear-Buffer CIGS Solar Cell Inversion
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Solution Overview
Problem
In thin-film-type solar cells, some solar light is reflected or absorbed by the buffer and front electrodes, reducing the amount of light that reaches the CIGS light absorption layer, thereby lowering photoelectric conversion efficiency.
Innovation Solution
The buffer and front electrodes are formed under the CIGS light absorption layer, and a grid electrode is positioned under the buffer layer, allowing solar light to reach the absorption layer without passing through these electrodes, and the electrodes are designed in a saw-toothed shape to minimize the distance electrons or holes need to travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the buffer layer and front electrode are formed on the CIGS light absorption layer, then the electrical connection and charge collection are improved, but the light absorption rate is reduced due to reflection and absorption by these layers
Solution Approach 1:
The patent inverts the conventional structure by placing the buffer layer and front electrode underneath the CIGS light absorption layer instead of on top. This inversion allows sunlight to reach the absorption layer directly without passing through these functional layers, eliminating their negative impact on light absorption while maintaining their essential electrical functions for charge collection and transport.
2Ease of manufacture
If thin-film light absorption layer is used, then the manufacturing cost is reduced, but the light absorption rate is lowered
Solution Approach 1:
The patent applies structural inversion to resolve the contradiction between thin-film cost advantages and light absorption performance. By inverting the device architecture, the thin CIGS layer can maintain its cost benefits while achieving superior light absorption since it is no longer obscured by the buffer layer and front electrode.
3Illumination intensity
If the front electrode and buffer layer are made with high light transmissivity, then the amount of solar light reaching the light absorption layer increases, but the manufacturing complexity increases
Solution Approach 1:
The patent eliminates the need for high light transmissivity materials in the front electrode and buffer layer by inverting their position. These layers are placed underneath the CIGS absorption layer where they perform their electrical functions without interfering with light transmission, thereby simplifying material selection and manufacturing processes.
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 configuration increases the amount of solar light reaching the light absorption layer, enhancing the solar cell's efficiency by reducing losses and optimizing the movement of electron-hole pairs.
Implementation Method 1
When solar light is input to such a solar cell, holes and electrons are generated in the semiconductor by energy of the input solar light
Implementation Method 2
by electric field on the PN junction, the holes are moved to the P-type semiconductor layer and the electrons are moved to the N-type semiconductor
Data Source
AI summary
The invention relates a thin-film solar cell. In the related art, a buffer layer, a transparent electrode, and a grid electrode are formed on a light absorption layer, but in the invention, the buffer layer and the transparent electrode are not formed on a light absorption layer, and the buffer layer, the transparent electrode, and the grid electrode are formed under a CIGS face such that solar light is directly input to the light absorption layer without obstacles, and the first electrode and the buffer layer are patterned in a saw-toothed structure to engage with each other to reduce a distance by which electrons or holes generated by absorbing light energy move to the electrode or the buffer layer.