Tandem Photovoltaic Interface Roughness for Reflection Reduction
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Solution Overview
Problem
Tandem photovoltaic devices face challenges in achieving high efficiency due to undesired reflections at the interface between submodules, which hinder the effective absorption of light and conversion of solar radiation into electrical energy.
Innovation Solution
The implementation of an interface with controlled surface roughness and refractive index mismatch between submodules, including a polished absorber layer and a transparent conducting layer, to reduce reflections and enhance optical coupling, allowing for improved transmission of light across the interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an interface is provided between submodules to optically couple them, then light transmission between submodules is improved, but reflection of light at the interface increases
Solution Approach 1:
The patent applies parameter changes by controlling the surface roughness of the interface layers to specific ranges (RMS 50-200 nm) and managing refractive index mismatches between layers. These parameter optimizations reduce light reflection at the interface while maintaining effective optical coupling between submodules, thereby improving light transmission efficiency without significant energy loss.
Solution Approach 2:
The patent implements local quality by creating distinct layers with specific properties at the interface: a first layer with controlled roughness (RMS 50-200 nm) adjacent to the second submodule, and a second layer with refractive index matching (mismatch < 0.2) positioned between the first layer and second submodule. This localized structural optimization minimizes reflection at critical interface regions while maintaining overall light transmission.
2Ease of manufacture
If the interface structure is simplified for manufacturing, then manufacturing complexity is reduced, but optical coupling performance deteriorates
Solution Approach 1:
The patent achieves a balance between manufacturing simplicity and optical performance by implementing a two-layer interface structure with specific local properties. The first layer provides roughness control (RMS 50-200 nm) for optical coupling, while the second layer provides refractive index matching (mismatch < 0.2). This localized optimization maintains manufacturing feasibility while ensuring reliable optical coupling performance.
Solution Approach 2:
The patent uses parameter changes to optimize the interface structure for both manufacturing and performance. By specifying concrete parameter ranges (roughness RMS 50-200 nm, refractive index mismatch < 0.2), the patent makes the interface structure manufacturable with standard processes while maintaining high optical coupling efficiency.
3Loss of energy
If surface roughness is increased to reduce reflection, then light scattering is improved, but surface polishability deteriorates
Solution Approach 1:
The patent resolves this contradiction by inverting the conventional approach: instead of increasing roughness to reduce reflection, it specifies a controlled roughness range (RMS 50-200 nm) that is achievable through standard polishing processes. This parameter optimization reduces reflection while maintaining surface polishability and manufacturing precision.
Solution Approach 2:
The patent applies local quality by creating a first layer with specific roughness properties (RMS 50-200 nm) at the interface region. This localized roughness control reduces light reflection through scattering while remaining compatible with standard surface polishing 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 approach significantly reduces light reflection, increasing the efficiency of tandem photovoltaic devices by ensuring that a higher percentage of incident light is absorbed by the submodules, thereby enhancing the overall energy conversion performance.
Implementation Method 1
The optical coupling of the first submodule and the second submodule can include reducing reflection of the portion of light passing through the interface
Implementation Method 2
A photovoltaic device generates electrical power by converting light into electricity using semiconductor materials that exhibit the photovoltaic effect
Implementation Method 3
The top submodule can absorb more higher-energy photons having a shorter wavelength, while the bottom submodule can absorb lower energy photons having a longer wavelength
Data Source
AI summary
Ways of making and using tandem photovoltaic devices are provided, where such devices can include a first submodule, a second submodule, and an interface between the first submodule and the second submodule. The interface permits a portion of light to pass therethrough and optically couples the first submodule and the second submodule. Optically coupling the first submodule and the second submodule includes reducing reflection of the portion of light passing through the interface.