Nanostructured Solar Cell Active Region for Optical Absorption
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Solution Overview
Problem
Conventional solar cells face a trade-off between thick active regions for sufficient optical absorption and thin layers for increased carrier density, leading to reduced open circuit voltage, and this limits their efficiency and cost-effectiveness.
Innovation Solution
The use of double-sided nano-structuring in the solar cell active region, with nano-voids between the active region and the substrate, enhances optical and electrical confinement, allowing for significantly thinner active regions without compromising optical absorption, thereby improving efficiency and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the active region thickness is increased to provide sufficient optical absorption, then optical absorption is improved, but carrier density decreases and open circuit voltage decreases
Solution Approach 1:
The patent transforms the planar active region into a three-dimensional nanostructured configuration with vertical pillars, cones, or wires. This dimensional transformation increases the effective optical path length and absorption cross-section without increasing the lateral footprint, enabling sufficient optical absorption in ultra-thin films while maintaining high carrier density and open circuit voltage
Solution Approach 2:
The patent employs nanostructured porous configurations including pillars, cones, and wires with controlled spacing and density. These porous structures increase the surface area and light-trapping capability within the active region, enhancing optical absorption while maintaining material efficiency and carrier collection
2Reliability
If the active region thickness is decreased to increase carrier density, then open circuit voltage is improved, but optical absorption decreases
Solution Approach 1:
By transitioning from a two-dimensional planar structure to a three-dimensional nanostructured architecture, the patent achieves enhanced light-trapping and absorption pathways within the thinned active region, compensating for the reduced thickness while maintaining high carrier density and voltage
Solution Approach 2:
The patent utilizes curved nanostructures such as conical shapes and cylindrical pillars instead of flat planar surfaces. These curved geometries provide multiple light reflection paths and increased interaction length with incident photons, enhancing absorption in ultra-thin configurations
3Quantity of substance
If nano-structuring is applied to reduce active region thickness, then material cost is reduced, but device complexity increases
Solution Approach 1:
The patent employs preliminary patterning steps and template-based fabrication approaches to pre-establish the nanostructure configuration before final device assembly. This preliminary structuring enables subsequent simplified processing steps and reduces overall manufacturing complexity despite the intricate nano-geometry
Solution Approach 2:
The patent develops universal nanostructure templates and fabrication protocols that can be applied across different solar cell architectures and material systems. This universality reduces device complexity by providing a standardized approach to nano-structuring that can be scaled and adapted without requiring entirely new fabrication methodologies
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 active region thicknesses to be reduced to less than 0.1 times the bulk absorption length, resulting in increased open-circuit voltage and absorption enhancement factors of 5 or more, while reducing the amount of semiconducting material required, thus lowering production costs and maintaining efficiency.
Implementation Method 1
electromagnetic radiation is absorbed to provide electrical power
Implementation Method 2
radiative generation of electrons and holes is significant
Implementation Method 3
The presence of such nano-voids advantageously increases both optical and electrical confinement in the active region
Data Source
AI summary
Improved solar cells are provided by nano-structuring the solar cell active region to provide high optical absorption in a thin structure, thereby simultaneously providing high optical absorption and high carrier collection efficiency. Double-sided nano-structuring is considered, where both surfaces of the active region are nano-structured. In cases where the active region is disposed on a substrate, nano-voids are present between the substrate and the active region, as opposed to the active region being conformally disposed on the substrate. The presence of such nano-voids advantageously increases both optical and electrical confinement in the active region.