Diatom Silica Anti-Reflective Coating for Photovoltaic Cover Layers
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Solution Overview
Problem
Existing photovoltaic devices suffer from reduced efficiency due to light reflection at the cover layer, with current anti-reflective coatings either relying on chemical materials or not effectively addressing the issue of light transmission.
Innovation Solution
A photovoltaic device with an anti-reflective coating comprising two adjacent porous silica layers in diatom frustules, where the first layer has a smaller pore diameter and pitch than the second layer, applied to the transparent cover layer to reduce light reflection and increase transmission to the active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent cover layer is used to protect the active layer, then protection from ambient atmosphere and dirt accumulation is improved, but light reflection increases reducing overall efficiency
Solution Approach 1:
The patent applies a porous silica coating layer on the transparent cover layer to reduce light reflection. The porous structure with controlled pore size and distribution creates optical interference effects that minimize reflection across a broad spectrum, thereby reducing energy loss while maintaining the protective function of the cover layer.
Solution Approach 2:
The patent uses a composite structure combining the transparent cover layer (glass or polymer) with a porous silica coating layer. This composite material system provides both the protective function of the cover layer and the anti-reflective properties of the porous silica, resolving the contradiction between protection and light transmission efficiency.
2Loss of energy
If synthetic anti-reflective coatings are used to reduce light reflection, then light transmission efficiency is improved, but manufacturing complexity and chemical use increase
Solution Approach 1:
The patent employs diatom frustules, which are natural biosynthesized porous silica structures produced by diatoms through self-assembly processes. These natural structures inherently possess the required porous morphology for anti-reflective properties, eliminating the need for complex synthetic manufacturing processes and reducing chemical usage while maintaining effective light transmission.
Solution Approach 2:
The patent utilizes diatom frustules, which are abundant, inexpensive natural materials that can be easily applied as a coating layer. The simplicity of using these naturally occurring structures reduces manufacturing complexity and cost compared to synthetic anti-reflective coatings, making the solution more economically viable.
3Use of energy by moving object
If diatom frustules are used for light trapping with larger diameter pores, then light trapping effect is improved, but anti-reflective performance deteriorates
Solution Approach 1:
The patent applies different pore size characteristics to different regions or layers of the porous silica coating. By controlling the pore size distribution and creating a gradient structure, the coating achieves both light trapping effects (through appropriate pore sizes) and anti-reflective performance (through controlled refractive index gradient), resolving the contradiction between these two optical functions.
Solution Approach 2:
The patent transitions from considering only pore diameter to incorporating pore depth, pore size distribution, and layer structure as additional dimensions of control. This multi-dimensional approach allows the porous silica coating to simultaneously achieve light trapping and anti-reflective properties by optimizing the vertical and horizontal pore characteristics independently.
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
The diatom frustule anti-reflective coating significantly enhances light transmission and reduces reflection, improving the overall efficiency of photovoltaic devices by allowing more light to reach the active layer, with the orientation and porosity of the layers crucial for optimal performance.
Implementation Method 1
Anti-reflective coatings (ARCs) are known in the art to reduce the amount of light reflected from the cover plate
Implementation Method 2
U.S. Pat. No. 8,153,282 B2 teaches that the anti-reflective layer should have a near portion (closer to the active layer) which has an effective index less than the far portion (further from the active layer) in order to achieve improved anti-reflective performance
Implementation Method 3
The anti-reflective coating reduces the reflection of light from the covering layer, such that an increased portion of the light is transmitted to the active layer
Data Source
AI summary
Photovoltaic device comprising an anti-reflective coating on a light incident side of a transparent cover layer, the anti-reflective coating comprising a layer of diatom frustules, each of the frustules comprising two adjacent and connected porous silica layers, the first porous silica layer having a pore diameter and pore pitch defining a first layer porosity, the second porous silicon layer having a pore diameter and pore pitch defining a second layer porosity, the second layer porosity being less than the first layer porosity, the layer of diatom frustules being arranged such that the first porous silica layer is light incident with respect to the second porous silica layer.