Transparent Bonding Structure for Multi-Junction Solar Cells

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Solution Overview

Problem

The challenge in multi-junction tandem solar cells is the lattice-mismatch between substrate and lower layer materials, leading to lattice-defects and inferior quality, which hinders the achievement of higher converting efficiency.

Innovation Solution

A bonding structure is introduced, featuring a transparent bonding structure with conductive layers and an adhesive layer between optoelectronic structures, including uneven surfaces or metal bulks, to facilitate electrical connection while maintaining high light transmission and bonding strength, thereby addressing lattice-mismatch issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a transparent bonding structure with conductive layers and adhesive layer is introduced to connect different optoelectronic structures, then the lattice-mismatch problem is solved and converting efficiency is improved, but the device structure becomes more complex and manufacturing difficulty increases

Engineering Contradiction:

Improveconverting efficiencyVSAvoidbonding structure complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent introduces a transparent bonding structure as an intermediary component between different optoelectronic structures with lattice-mismatch. This bonding structure includes a substrate, a first bonding layer, and a second bonding layer, serving as a mediator that connects materials with different lattice constants without requiring direct bonding between them, thus solving the lattice-mismatch problem while maintaining structural integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bonding structure employs composite material design by combining different materials with specific properties: the substrate provides mechanical support, the first bonding layer provides adhesion to the first optoelectronic structure, and the second bonding layer provides adhesion to the second optoelectronic structure. This composite approach allows each layer to be optimized for its specific function while working together as an integrated solution

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If the bonding structure uses transparent adhesive layer to maintain light transmission, then light transmission is improved, but bonding strength may be reduced compared to opaque adhesives

Engineering Contradiction:

Improvelight transmissionVSAvoidbonding strength

Core Design Contradiction:

Illumination intensityVSStrength

Solution Approach 1:

The patent applies parameter changes by carefully selecting and optimizing the thickness, refractive index, and material composition of the transparent adhesive layers. The first bonding layer and second bonding layer are designed with specific optical parameters to maximize light transmission while maintaining sufficient bonding strength through controlled physical and chemical properties

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple layers are added to solve lattice-mismatch, then material compatibility is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvematerial compatibilityVSAvoidlayer alignment precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-processing the bonding surfaces and preparing the bonding layers before final assembly. The substrate and bonding layers are prepared in advance with appropriate surface treatments and material deposition, ensuring that when the structures are assembled, the lattice-mismatch is already accommodated and alignment is facilitated

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The bonding structure employs local quality by having different layers with different properties optimized for their specific locations and functions. The substrate may have different thermal expansion properties, the first bonding layer may have different adhesion characteristics, and the second bonding layer may have different optical properties, allowing each local region to be optimized for its specific requirement

Inventive Principle:

Principle #3Local quality

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 solution enhances the connecting efficiency between different materials, improving the quality and efficiency of solar cells by reducing lattice-defects and increasing light transmission, ultimately leading to higher converting efficiency.

Implementation Method 1

a transparent adhesive layer formed in-between the first conductive layer and the second conductive layer to connect therewith electrically

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

a surface for the first conductive layer and/or the second conductive layer to contact with each other includes an uneven surface

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS8581093B2Optoelectronical semiconductor device

Publication Date: 2013.11.12 ENNOSTAR CORP

AI summary

An optoelectronical semiconductor device having a bonding structure comprises a first optoelectronical structure, a second optoelectronical structure, and a transparent bonding structure formed in-between.