Solar Cell Electrode Bonding Structure for Space-Grade Interconnects

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Solution Overview

Problem

Solar cells for outer space applications face challenges with adhesive strength due to the presence of Mo(Se,S)2 and Ti(Se,S)2 layers, which reduce bonding effectiveness and increase the risk of electrical connection failure under temperature changes and UV exposure.

Innovation Solution

An electrode structure with a wiring element having a melting point of 230°C or higher, where the bonding layer contains diffused Se and S elements, promoting high adhesive strength between the conductor and wiring element through alloy phase formation and diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If soldering or adhesion methods are used to bond the interconnector, then the bonding process is simple and low-cost, but the adhesive strength decreases under temperature changes and UV exposure in outer space environments

Engineering Contradiction:

Improvebonding process simplicityVSAvoidadhesive strength under temperature changes and UV exposure

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the bonding method from chemical adhesion (soldering/adhesive) to physical metallurgical bonding (resistance welding). This parameter change in bonding mechanism eliminates the reliance on adhesives that degrade under UV and temperature changes, achieving reliable bonding in outer space environments while maintaining manufacturing feasibility through automated resistance welding processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the chemical bonding system (adhesives and solder) with a physical/electrical bonding system (resistance welding). This substitution eliminates the harmful effects of chemical adhesives under UV exposure and extreme temperature variations, providing a more reliable bonding solution for space applications

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the interconnector is bonded by resistance welding, then the adhesive strength is high and reliable under temperature changes, but the manufacturing complexity increases

Engineering Contradiction:

Improveadhesive strength under temperature changesVSAvoidbonding process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The resistance welding process utilizes the electrical conductivity and thermal properties of the materials themselves to achieve bonding. The interconnector and electrode serve as both the components to be joined and the medium for energy transfer, eliminating the need for additional bonding agents or complex multi-step processes, thereby reducing manufacturing complexity despite the advanced bonding technique

Inventive Principle:

Principle #25Self-service

3Use of energy by moving object

If Mo(Se,S)2 and Ti(Se,S)2 layers are present on the electrode, then the photoelectric conversion performance is improved, but the bonding strength between the electrode and wiring element decreases

Engineering Contradiction:

Improvephotoelectric conversion efficiencyVSAvoidbonding strength between electrode and wiring element

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The patent applies local quality by making the Mo(Se,S)2 and Ti(Se,S)2 layers non-uniform: they are present in the photoelectric conversion region to enhance performance, but intentionally removed or reduced in the bonding region to ensure strong electrical connection. This spatial differentiation resolves the contradiction between photoelectric efficiency and bonding strength

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the electrode surface into functionally distinct regions: a photoelectric conversion region with Mo(Se,S)2 and Ti(Se,S)2 layers for high efficiency, and a bonding region with removed or reduced layers for strong wiring attachment. This segmentation allows each region to optimize its specific function without compromising the other

Inventive Principle:

Principle #1Segmentation

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

Enhances the adhesive strength between the electric conductor and wiring element, ensuring reliable electrical connections in extreme space environments.

Implementation Method 1

the bonding layer contains diffused Se and S elements

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

promoting high adhesive strength between the conductor and wiring element through alloy phase formation and diffusion

Methodology Applied

Scientific EffectAlloy phase formation:

Data Source

PatentUS20240038910A1Electrode structure and manufacturing method of solar cell

Publication Date: 2024.02.01 IDEMITSU KOSAN CO LTD

AI summary

An electrode structure of a solar cell includes an electric conductor on a substrate side of a chalcogen solar cell, and a wiring element to be electrically connected with the electric conductor. The wiring element is stacked on and bonded with the electric conductor. The melting point of the wiring element is equal to or higher than 230° C., and the electric conductor in the region corresponding to the wiring element includes a part of the metal element of the wiring element.