Backside Textured Silicon Solar Cell Infrared Absorption
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Solution Overview
Problem
Existing silicon solar cells face challenges in optimizing the absorption of both infrared and visible light energy, with front side texturing benefiting visible light absorption but not effectively addressing infrared light utilization, and vice versa.
Innovation Solution
A semiconductor solar cell design featuring a planar front surface with a transparent layer for visible and infrared wavelengths, a textured diffusive scattering layer on the back surface for infrared radiation, and a reflecting layer behind the textured layer to enhance infrared absorption, along with the option of stacking substrates to further improve infrared energy capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If thick layers of white paint are applied to the backside to enhance infrared absorption, then infrared energy capture is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of using thick white paint layers, the invention uses a thin textured structure that replicates the light-trapping function through geometric features. This copying of the light management function through structure rather than material reduces complexity.
Solution Approach 2:
The invention changes the approach from material-based infrared enhancement (thick white paint) to structure-based enhancement (textured backside). By changing the parameter from material thickness to surface geometry, it achieves infrared trapping with reduced complexity.
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 design significantly enhances the absorption efficiency of infrared light, achieving a path length enhancement factor of up to 66 and improving overall energy conversion efficiency, comparable to thicker crystalline solar cells, while maintaining optimal visible light absorption.
Implementation Method 1
A textured layer is disposed at a second surface of the silicon substrate, the textured layer being a diffusive radiation scattering layer for infrared wavelengths of radiation
Implementation Method 2
a reflecting layer disposed on the textured layer and spaced apart from the second surface by the textured layer, whereby infrared wavelengths of radiation are returned through the textured layer toward the first semiconductor substrate
Implementation Method 3
a layer transparent to visible light and infrared wavelengths is disposed at the first surface. This layer is internally reflective to infrared wavelengths of radiation scattered within the first semiconductor substrate
Data Source
AI summary
The absorption coefficient of silicon for infrared light is very low and most solar cells absorb very little of the infrared light energy in sunlight. Very thick cells of crystalline silicon can be used to increase the absorption of infrared light energy but the cost of thick crystalline cells is prohibitive. The present invention relates to the use of less expensive microcrystalline silicon solar cells and the use of backside texturing with diffusive scattering to give a very large increase in the absorption of infrared light. Backside texturing with diffusive scattering and with a smooth front surface of the solar cell results in multiple internal reflections, light trapping, and a large enhancement of the absorption of infrared solar energy.