Solar Cell Electrode Structure Preventing P-N Junction Penetration

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Solution Overview

Problem

Current methods for fabricating front side electrodes in solar cells, such as those using metal paste with glass frit, result in overreaction with the silicon substrate, leading to reduced efficiency due to penetration of the P-N junction and limitations in line width, and existing alternative methods are complex and prone to substrate damage.

Innovation Solution

A solar cell electrode structure comprising a first electrode layer that does not react with the photoelectric conversion layer or antireflective layer during sintering, and a second electrode layer that reacts with the antireflective layer to form electrical connections, allowing for the use of inkjet printing or electroplating for the first layer and screen printing for the second, without penetrating the P-N junction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal paste with glass frit is used for fabricating front side electrode, then adhesion of metal electrode to silicon substrate is improved, but metal electrode penetrates P-N junction and efficiency of solar cell deteriorates

Engineering Contradiction:

Improveadhesion of metal electrode to silicon substrateVSAvoidefficiency of solar cell

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The electrode structure is divided into two separate layers: a first electrode layer in direct contact with the silicon substrate for adhesion, and a second electrode layer on top for conductivity. This segmentation prevents the conductive metal from penetrating the P-N junction while maintaining strong adhesion through the first layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first electrode layer acts as an intermediary between the silicon substrate and the second electrode layer. It provides the necessary adhesion to the substrate while preventing the second layer from reacting with or penetrating the P-N junction, thus mediating between adhesion requirements and efficiency preservation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If glass frit with diameter of 10 micrometers to tens of micrometers is used, then adhesion is achieved, but minimum line width of conductive grid is confined to greater than 70 micrometers

Engineering Contradiction:

Improveadhesion of electrodeVSAvoidline width of conductive grid

Core Design Contradiction:

StrengthVSLength of moving object

Solution Approach 1:

By separating the adhesion function (first layer) from the conductivity function (second layer), the patent enables the second layer to be made much thinner than traditional glass frit particles, achieving line widths less than 70 micrometers while maintaining adhesion through the first layer.

Inventive Principle:

Principle #1Segmentation

3Reliability

If openings are formed on antireflective layer to expose underlying silicon substrate, then electrical connection is achieved, but manufacturing process becomes complicated and silicon substrate is damaged

Engineering Contradiction:

Improveelectrical connectionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of forming openings in the antireflective layer to expose the substrate and then forming electrodes, this patent inverts the approach by forming the first electrode layer directly on the substrate before applying the antireflective layer. This eliminates the need for opening formation and avoids substrate damage.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The first electrode layer is formed preliminarily on the silicon substrate before the antireflective layer is applied. This preliminary action ensures electrical connection is established without requiring subsequent opening formation, simplifying the manufacturing process and preventing substrate damage.

Inventive Principle:

Principle #10Preliminary action

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 prevents efficiency reduction, enables the formation of electrodes with smaller line widths, increases the irradiated area, and simplifies the manufacturing process by avoiding the need for opening formation in the antireflective layer, thus enhancing solar cell performance and reducing costs.

Implementation Method 1

enables the use of inkjet printing or electroplating for the first layer

Methodology Applied

Scientific EffectInkjet printing:

Implementation Method 2

enables the use of inkjet printing or electroplating for the first layer

Methodology Applied

Scientific EffectElectroplating: Electroplating

Implementation Method 3

a second electrode layer that reacts with the antireflective layer during a sintering process

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS8664520B2Electrode of solar cell

Publication Date: 2014.03.04 IND TECH RES INST

AI summary

Provided is an electrode of a solar cell including a first electrode layer, a photoelectric conversion layer, an antireflective layer, and a second electrode layer. The first electrode layer is disposed on the photoelectric conversion layer. The antireflective layer is disposed on the photoelectric conversion layer to cover the first electrode layer. The second electrode layer is disposed on the antireflective layer and electrically connected to the first electrode layer, wherein a material of the first electrode layer does not react with the photoelectric conversion layer and the antireflective layer during a sintering process, and at least a material of the second electrode layer reacts with the antireflective layer during the sintering process.