Adhesiveless Solar Cell Bonding for Thin Absorber Handling
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Solution Overview
Problem
Conventional solar cell fabrication processes are limited by the handling and processing of thin solar absorber materials, which increases costs and reduces efficiency, and current methods require multiple steps and significant mechanical or thermal stress on the absorber material substrates.
Innovation Solution
The method involves double-sided bonding of solar absorber material substrates to fully processed optically transparent substrates using adhesiveless or conductive adhesive bonding, reducing processing steps and stress, enabling the use of thin substrates and various solar cell architectures, such as HIT and IBC cells, with direct chemical bonding facilitated by Vander Waals, capillary, or electrostatic forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thin solar absorber materials are used to improve efficiency and reduce cost, then conversion efficiency increases and material cost decreases, but handling and processing difficulty increases
Solution Approach 1:
A temporary carrier substrate is introduced as an intermediary to support thin solar absorber materials during fabrication and handling. The substrate acts as a mediator that enables processing of fragile thin layers without direct mechanical stress, and is removed after bonding to the final substrate, resolving the contradiction between using thin efficient absorbers and maintaining ease of manufacture.
Solution Approach 2:
The thin solar absorber material is pre-bonded to a temporary carrier substrate before final assembly, providing mechanical support and protection during subsequent processing steps. This prior cushioning prevents damage to the thin absorber layer while maintaining the benefits of thin-film efficiency.
2Reliability
If conventional multi-step fabrication processes are used to ensure proper layer formation, then device reliability improves, but processing complexity and stress on substrates increase
Solution Approach 1:
Required layers and structures are pre-formed on the temporary carrier substrate before bonding to the solar absorber material. This preliminary action consolidates multiple fabrication steps into fewer operations, reducing overall processing complexity while maintaining device reliability through controlled layer formation.
Solution Approach 2:
Multiple processing steps are merged into a single bonding operation where the temporary carrier substrate with pre-formed layers is bonded directly to the solar absorber material. This combining of operations reduces the number of discrete steps and minimizes mechanical stress on substrates during processing.
3Productivity
If thin absorber layers are used to achieve higher open-circuit voltage, then conversion efficiency improves, but mechanical strength decreases
Solution Approach 1:
The temporary carrier substrate serves as a mechanical intermediary that compensates for the reduced strength of thin absorber layers. During handling and bonding, the carrier substrate provides the necessary mechanical strength, allowing thin absorber layers to be used for high voltage output without compromising structural integrity.
Solution Approach 2:
The mechanical strength requirement is localized to specific regions where the thin absorber layer is bonded to the carrier substrate and later to the final substrate. The thin absorber layer maintains its electrical properties for high voltage while the substrate-provided strength addresses mechanical requirements only where structurally necessary.
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 fabrication costs and increases efficiency by minimizing substrate handling, allowing for thinner absorber layers and simplified processing, while maintaining mechanical integrity and enabling efficiencies beyond 25% in solar cell performance.
Implementation Method 1
adhesiveless bonding... direct chemical bonding... Vander Waals forces
Implementation Method 2
capillary forces
Implementation Method 3
electrostatic forces
Implementation Method 4
The TCO can provide greater than 80% transmission over a wavelength range from about 250 nm to 1.1 μm
Implementation Method 5
Electron-hole pairs are generated in the active layer by incident photons having sufficient energy relative to the band gap energy from the sunlight
Implementation Method 6
Electron-hole pairs are generated in the active layer by incident photons
Data Source
AI summary
A solar cell includes a first processed optically transparent (transparent) substrate and a second processed transparent substrate, wherein at least one of the first processed transparent substrate and second processed transparent substrate includes at least one electrode thereon. At least one solar absorber material substrate having a first side and a second side is between the first and second processed transparent substrates. The solar absorber material substrate is bonded by an adhesiveless bonded interface on both the first side and the second side to the first and second processed transparent substrates.