Ultra-Thin Solar Cell Surface Passivation and Light Trapping
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Solution Overview
Problem
Current photovoltaic systems are not competitive with fossil-fuel generated electricity due to high costs, and reducing solar cell size to lower costs also reduces efficiency, necessitating a method to enhance efficiency while minimizing semiconductor material usage.
Innovation Solution
The method involves forming passivation layers, diffraction layers, anti-reflective layers, and reflective layers on ultra-thin solar cells to facilitate carrier collection and internal reflection and absorption of photons, using integrated circuit and microfabrication techniques to minimize material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of photovoltaic solar cells is reduced to lower costs, then material cost decreases, but cell efficiency deteriorates
Solution Approach 1:
The patent applies passivation layers on all surfaces (front, back, and side walls) of the ultra-thin solar cell, transitioning from conventional front-and-back surface treatment to three-dimensional all-surface treatment. This dimensional extension ensures comprehensive carrier collection and light management in ultra-thin structures where traditional two-surface approaches fail to maintain efficiency
Solution Approach 2:
The patent modifies optical parameters by introducing diffraction layers and reflective layers that change light propagation paths. The diffraction layer creates multiple internal reflections and extends light path length within the ultra-thin cell, while the reflective layer on the back surface redirects unabsorbed light back into the active layer, effectively increasing photon absorption without increasing material thickness
2Reliability
If passivation layers are formed on all surfaces including side walls, then carrier collection improves, but device complexity increases
Solution Approach 1:
The passivation layer structure serves multiple functions simultaneously: it passivates surface states on all surfaces to reduce recombination, provides mechanical support for the ultra-thin cell, and creates a platform for subsequent optical layers (diffraction and reflective layers). This multi-functionality consolidates what would otherwise be separate components into a unified structure
Solution Approach 2:
The fabrication process segments the complex all-surface passivation into manageable steps: first forming the passivation layer on the front surface, then extending it to side walls through lateral growth, and finally completing it on the back surface. This segmentation allows conventional fabrication techniques to achieve three-dimensional coverage that would otherwise require complex specialized processes
3Reliability
If diffraction and reflective layers are added to enhance light absorption, then photon absorption improves, but manufacturing complexity increases
Solution Approach 1:
The patent merges the diffraction layer and reflective layer into a coordinated optical management system where the diffraction layer on the front surface and the reflective layer on the back surface work together to trap light within the ultra-thin cell. This merging creates a synergistic effect where light is diffracted at the front and reflected at the back, maximizing internal path length and absorption probability without requiring each layer to be independently complex
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 achieves high efficiency in ultra-thin solar cells by passivating all surfaces, enabling carrier collection across all surfaces and optimizing light absorption, thereby improving overall cell performance while reducing material consumption.
Implementation Method 1
A diffraction layer is formed on the top side of the device. The diffraction layer serves to diffract light entering the device.
Implementation Method 2
A reflective layer can also be formed along the bottom side of the device. The reflective layer reflects the diffracted light internally within the device.
Implementation Method 3
A passivation layer (which could be a 'surface field' formed by doping the surface of the material with n or p-type dopants) is formed along the top side, the bottom side and opposing side walls of the device. The passivation layer serves to passivate the device and facilitate carrier collection around the device.
Data Source
AI summary
A method, system and apparatus including a device cell having a top side, a bottom side and opposing side walls. A passivation layer is formed along the top side, the bottom side and opposing side walls of the device cell. The passivation layer serves to passivate the device cell and facilitate carrier collection around the device cell. An anti-reflective layer is formed over the passivation layer and an optical layer is formed on the top side of the device cell. The optical layer reflects light within the device cell. The apparatus may further include a reflective layer formed along the bottom side of the device cell, the reflective layer to reflect light internally within the device cell.