Solar Cell Tunnel Contacts via Paste Metallization

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Solution Overview

Problem

Existing solar cell manufacturing methods are aggressive towards tunnel layers, leading to damage or destruction, and conventional metallization techniques are not cost-effective for forming efficient contacts.

Innovation Solution

A solar cell manufacturing method using a metallization paste with glass frit that forms a tunnel layer between the semiconductor substrate and the paste metallization during heat treatment, allowing for the creation of efficient tunnel contacts without damaging the tunnel layer, and incorporating a passivation layer for enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a metallization paste is used to form contacts on the tunnel layer, then the manufacturing cost is reduced and productivity is improved, but the tunnel layer is damaged or destroyed by the aggressive paste constituents

Engineering Contradiction:

Improvemanufacturing costVSAvoidtunnel layer integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A dielectric intermediate layer is introduced between the tunnel layer and the metallization paste. This intermediate layer acts as a protective barrier that prevents the aggressive constituents of the metallization paste from attacking and destroying the tunnel layer, while still allowing the paste to form effective electrical contacts through the intermediate layer to the tunnel layer beneath.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The dielectric intermediate layer is applied to the tunnel layer before the metallization paste is applied. This preliminary protective coating prevents damage before the aggressive paste constituents can contact and destroy the tunnel layer, enabling subsequent paste metallization processes to proceed without compromising tunnel layer integrity.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a vapor deposition method is used to deposit metal layer on the tunnel layer, then the tunnel layer integrity is maintained, but the manufacturing cost increases and productivity decreases

Engineering Contradiction:

Improvetunnel layer integrityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The dielectric intermediate layer enables the use of cost-effective paste metallization methods by protecting the tunnel layer from damage. This intermediary approach allows conventional, economical paste-based manufacturing processes to be used instead of expensive vapor deposition methods, while still maintaining tunnel layer integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the metallization paste is applied directly to the tunnel layer, then the contact efficiency is improved, but the tunnel layer is attacked and decomposed by the paste constituents

Engineering Contradiction:

Improvecontact efficiencyVSAvoidpaste aggression

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The dielectric intermediate layer serves as a protective mediator between the metallization paste and the tunnel layer. It allows the paste to maintain effective electrical contact with the tunnel layer while preventing the aggressive organic and inorganic constituents of the paste from attacking, decomposing, or destroying the tunnel layer structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The dielectric intermediate layer provides beforehand protection by being applied to the tunnel layer prior to paste metallization. This protective cushioning layer prevents the harmful effects of the metallization paste constituents from reaching and damaging the tunnel layer, enabling safe and effective contact formation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 method enables the formation of highly efficient tunnel contacts with a cost-effective metallization process, maintaining the integrity of the tunnel layer and improving solar cell efficiency by using a paste metallization with porosity and resistivity differences compared to traditional metal thin films.

Implementation Method 1

heat-treating the semiconductor substrate provided with the metallization paste, in that a paste metallization is formed from the metallization paste

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 2

the metallization paste which is applied to the semiconductor substrate and produces the paste metallization during the heat treatment contains a constituent such as, for example, glass fit, which produces the tunnel layer between the semiconductor substrate and the paste metallization during the heat treatment

Methodology Applied

Scientific EffectGlass frit decomposition: Decomposition (biological)

Implementation Method 3

tunnel layers serve to form efficient contacts, what are termed tunnel contacts. Tunnel layers are formed from very thin dielectric layers

Methodology Applied

Scientific EffectQuantum tunneling:

Implementation Method 4

The tunnel layer may moreover exert a passivating action on the semiconductor surface, i.e. may be formed as a passivation layer

Methodology Applied

Scientific EffectPassivation:

Data Source

PatentUS10658527B2Solar cell and solar cell manufacturing method

Publication Date: 2020.05.19 HANWHA Q CELLS GMBH

AI summary

A solar cell comprising: a semiconductor substrate; a metallization paste on a surface of the semiconductor substrate; and a tunneling layer between the substrate surface and the metallization paste.