Amorphous Silicon Layer Density for Solar Cell Passivation

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Solution Overview

Problem

It is challenging to maintain a high fill factor and open circuit voltage in solar cells with miniaturized texture structures, as the occupancy of the epitaxial growth region in the non-crystalline silicon layer increases, leading to reduced passivation effects and decreased power generation efficiency.

Innovation Solution

A solar cell design featuring a silicon substrate with a texture structure, where a non-crystalline silicon layer is formed with a first epitaxial layer, a first amorphous layer, and a second amorphous layer, with the first amorphous layer having a lower density than the second amorphous layer, allowing for controlled epitaxial growth inhibition and improved passivation, thereby maintaining high fill factor and open circuit voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the texture structure is miniaturized (reduced in diameter), then the fill factor increases, but the open circuit voltage decreases

Engineering Contradiction:

Improvefill factorVSAvoidopen circuit voltage

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The non-crystalline silicon layer is segmented into multiple sub-layers with different densities (first amorphous layer with lower density, second amorphous layer with higher density). This segmentation allows independent optimization of each layer's function: the lower density layer provides better passivation for higher open circuit voltage, while the overall miniaturized texture structure maintains high fill factor.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the non-crystalline silicon layer are given different densities locally. The first amorphous layer (lower density) is positioned where enhanced passivation is needed, while the second amorphous layer (higher density) provides structural stability. This local quality differentiation resolves the contradiction between fill factor and open circuit voltage.

Inventive Principle:

Principle #3Local quality

2Productivity

If the occupancy of the epitaxial growth region in the non-crystalline silicon layer increases, then the fill factor increases, but the passivation effect decreases

Engineering Contradiction:

Improvefill factorVSAvoidpassivation effect

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The non-crystalline silicon layer is divided into multiple density layers, with the first amorphous layer (lower density) providing superior passivation properties. This segmentation allows the system to maintain high epitaxial growth region occupancy for high fill factor while the lower density amorphous layer compensates for reduced passivation effect through its enhanced passivation capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The density parameter of the amorphous silicon layer is changed and optimized. By creating a first amorphous layer with lower density than the second amorphous layer, the patent exploits the relationship between density and passivation quality, where lower density amorphous silicon provides better passivation effects, thus maintaining reliability despite increased epitaxial growth region occupancy.

Inventive Principle:

Principle #35Parameter changes

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 design effectively adjusts the fill factor and open circuit voltage by managing the thickness of the epitaxial layer and passivation layers, ensuring high power generation efficiency even with miniaturized texture structures.

Implementation Method 1

a first epitaxial layer including a crystalline region epitaxially grown on the silicon substrate

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Implementation Method 2

forming, on a first principal surface of a silicon substrate including a texture structure, a first non-crystalline silicon layer including recesses and protrusions reflecting the texture structure, by chemical vapor deposition using a raw material gas containing silicon

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS11038071B2Solar cell, solar cell module, and method for manufacturing solar cell

Publication Date: 2021.06.15 RISEN ENERGY CO LTD

AI summary

A solar cell includes: a silicon substrate including a texture structure in a first principal surface; and a first non-crystalline silicon layer formed on the first principal surface of the silicon substrate and including recesses and protrusions reflecting the texture structure. At a valley portion in the recesses and protrusions, the first non-crystalline silicon layer includes, in the stated order: a first epitaxial layer including a crystalline region epitaxially grown on the silicon substrate; a first amorphous layer which is a non-crystalline silicon layer; and a second amorphous layer which is a non-crystalline silicon layer. The density of the first amorphous layer is less than the density of the second amorphous layer.