Solar Cell Element with Dopant Gradient for Efficiency

Solution Overview

Problem

Conventional solar cell elements face challenges in achieving high conversion efficiency due to high resistance in second conductivity-type layers and recombination loss of photogenerated carriers.

Innovation Solution

A method involving a semiconductor substrate with a first conductivity type, heated in atmospheres with varying dopant concentrations to create a dopant concentration gradient, resulting in a high-concentration dopant layer near the surface and a low-concentration dopant layer inside, reducing resistance and recombination loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a uniform dopant concentration is used in the second conductivity-type layer, then the manufacturing process is simple, but the resistance of the layer is high and recombination loss occurs

Engineering Contradiction:

Improveconversion efficiencyVSAvoiddopant concentration profile

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating different dopant concentrations at different depths within the second conductivity-type layer. The surface region has a first dopant concentration while the inner region has a second dopant concentration, optimizing each region's properties for its specific function: surface region for carrier collection and inner region for reducing recombination loss.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the second conductivity-type layer into distinct concentration zones. By dividing the layer into a surface portion with higher dopant concentration and an inner portion with lower dopant concentration, it achieves both low resistance at the surface and reduced recombination loss in the bulk.

Inventive Principle:

Principle #1Segmentation

2Reliability

If high dopant concentration is applied throughout the second conductivity-type layer, then resistance is reduced, but recombination loss of photogenerated carriers increases

Engineering Contradiction:

Improvecarrier conductionVSAvoidrecombination loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating different dopant concentrations at different depths within the second conductivity-type layer. The surface region has a first dopant concentration while the inner region has a second dopant concentration, optimizing each region's properties for its specific function: surface region for carrier collection and inner region for reducing recombination loss.

Inventive Principle:

Principle #3Local quality

3Reliability

If low dopant concentration is used in the second conductivity-type layer, then recombination loss is reduced, but the resistance of the layer increases

Engineering Contradiction:

Improvecarrier conductionVSAvoidrecombination loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating different dopant concentrations at different depths within the second conductivity-type layer. The surface region has a first dopant concentration while the inner region has a second dopant concentration, optimizing each region's properties for its specific function: surface region for carrier collection and inner region for reducing recombination loss.

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 configuration enhances carrier conduction and photocurrent transmission, increasing the solar cell's efficiency and sensitivity to short-wavelength light, while maintaining a high sheet resistance.

Implementation Method 1

heating a semiconductor substrate having a first conductivity type in a first atmosphere which contains a dopant having a second conductivity type and which has a first dopant concentration; heating in a second atmosphere the semiconductor substrate heated in the first atmosphere, the second atmosphere having a second dopant concentration less than the first dopant concentration

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS8975172B2Solar cell element and method for manufacturing solar cell element

Publication Date: 2015.03.10 KYOCERA CORP

AI summary

[Object] To provide a method for manufacturing a solar cell element including a semiconductor substrate that includes a high-concentration dopant layer located near the surface of the semiconductor substrate and a low-concentration dopant layer located more inside the semiconductor substrate than the high-concentration dopant layer.[Solving Means] A method includes heating a semiconductor substrate having a first conductivity type in a first atmosphere which contains a dopant having a second conductivity type and which has a first dopant concentration; heating in a second atmosphere the semiconductor substrate heated in the first atmosphere, the second atmosphere having a second dopant concentration less than the first dopant concentration; and heating in a third atmosphere the semiconductor substrate heated in the second atmosphere, the third atmosphere having a third dopant concentration greater than the second dopant concentration.