Semitransparent Thin-Film Solar Module Without Color Filter Effect
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Solution Overview
Problem
Current semitransparent thin-film solar modules face challenges in achieving high visible-light transmittance while maintaining electrical efficiency, often resulting in undesirable color filter effects due to the thin absorber layer used in conjunction with crystalline silicon technology.
Innovation Solution
The development of a semitransparent thin-film solar module with integrated serially connected solar cells, featuring optically transparent zones that are rear-electrode-layer-free and absorber-layer-free, allowing for high visible-light transmittance of at least 85% by strategically arranging patterning zones and using chalcopyrite-based absorbers to optimize transparency and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a thin absorber layer is used to achieve high visible-light transmittance, then transparency is improved, but an undesirable color filter effect develops
Solution Approach 1:
The patent changes the material composition of the absorber layer from thin-film silicon to chalcopyrite-based materials (Cu(In,Ga)(S,Se)2), which have different optical properties. This material substitution allows achieving high visible-light transmittance without the color filter effect that plagues thin silicon absorbers, as chalcopyrites have a direct bandgap that enables efficient light absorption without strong wavelength-dependent filtering in the visible range.
Solution Approach 2:
The patent employs composite material structures including multiple thin-film layers (buffer layer, absorber layer, transparent electrode layers) with specific material combinations. The chalcopyrite-based absorber is combined with appropriate buffer and electrode materials to optimize both optical transparency and electrical performance, creating a composite structure that eliminates the color filter effect while maintaining high visible-light transmittance.
2Illumination intensity
If the absorber layer is made thin to increase transparency, then visible-light transmittance is improved, but electrical efficiency deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of absorber material from indirect-bandgap thin-film silicon to direct-bandgap chalcopyrite materials. This parameter change enables the absorber to be very thin (high transparency) while still maintaining high electrical efficiency, because direct-bandgap materials absorb light much more efficiently per unit thickness, generating sufficient electron-hole pairs even in thin layers.
Solution Approach 2:
The patent applies local quality optimization by creating specific structural features within the thin-film module, including transparent zones with different layer configurations and localized variations in layer thickness and composition. These local optimizations ensure that electrical efficiency is maintained in active regions while maximizing transparency in specific zones, resolving the contradiction between overall transparency and localized power generation efficiency.
3Illumination intensity
If optically transparent zones are introduced to increase visible-light transmittance, then transparency is improved, but device complexity increases
Solution Approach 1:
The patent segments the solar module into distinct functional zones: optically active zones with full layer structure for power generation and optically transparent zones with modified layer structure for light transmission. This segmentation is achieved through patterning techniques that create spatially varying layer configurations, allowing the module to simultaneously perform both power generation and light transmission functions without requiring entirely separate components.
Solution Approach 2:
The patent creates a multi-functional solar module where the same substrate and base layer structure serve dual purposes: generating electrical power in opaque zones and transmitting visible light in transparent zones. The chalcopyrite-based thin-film structure itself provides both photovoltaic functionality and optical transparency, eliminating the need for separate transparent and active components, thus reducing overall device complexity despite the presence of multiple functional zones.
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 enables a balance between high electrical output and adequate optical transmittance, eliminating the color filter effect and enhancing the visual appeal of the modules, with the ratio of optically transparent zones to total area ranging from 5% to 50%, effectively addressing the limitations of previous technologies.
Implementation Method 1
solar cells for photovoltaic energy generation
Implementation Method 2
significantly higher efficiency levels can be achieved by chalcopyrite-based absorbers than with absorbers based on amorphous silicon
Data Source
AI summary
A thin-film solar module with a substrate and a layer structure applied thereon that comprises a rear electrode layer, a front electrode layer, and an absorber layer arranged between the back electrode layer and the front electrode layer. Serially connected solar cells are formed in the layer structure by patterning zones, wherein each patterning zone comprises a first patterning line for subdividing at least the rear electrode layer, a second patterning line for subdividing at least the absorber layer, and at least one third patterning line for subdividing at least the front electrode layer. At least one patterning zone has one or more optically transparent zones in a zone region reduced by the first patterning line, which are in each case rear-electrode-layer-free, wherein the one or more optically transparent zones are implemented such that the rear electrode layer is continuous in the zone region.