Selective Emitter Solar Cell Structure for Passivated Ohmic Contact

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Solution Overview

Problem

The issue with existing selective emitter laser doping technology is that the electrode sometimes contacts the lightly doped region, affecting the passivation on the substrate surface of solar cells.

Innovation Solution

A solar cell design with a doped layer comprising a heavily doped region, edge regions, and connecting regions, where the electrode is positioned to form an ohmic contact only with the heavily doped region, and the doping concentrations and junction depths decrease sequentially, reducing carrier recombination and improving passivation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electrode is positioned to contact the lightly doped region to reduce contact resistance, then the contact resistance decreases, but the passivation on the substrate surface deteriorates due to carrier recombination

Engineering Contradiction:

Improvecontact resistanceVSAvoidcarrier recombination

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The doped layer is segmented into multiple regions with different doping concentrations: a heavily doped region directly under the electrode for low contact resistance, and a lightly doped region surrounding it for good passivation. This spatial segmentation allows each region to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the doped layer are assigned different doping concentrations according to their specific functional requirements. The heavily doped region provides excellent electrical contact where the electrode touches, while the lightly doped region maintains effective passivation in areas where carrier recombination must be minimized.

Inventive Principle:

Principle #3Local quality

2Reliability

If the doping concentration is increased to improve ohmic contact, then the contact quality improves, but the carrier recombination increases affecting passivation

Engineering Contradiction:

Improveohmic contact qualityVSAvoidcarrier recombination loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The doping concentration is locally optimized: high doping concentration is applied only in the heavily doped region where ohmic contact is required, while lower doping concentration is used in the lightly doped region where passivation is critical. This local quality differentiation resolves the contradiction between contact quality and energy loss.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The doped layer is divided into functionally distinct segments: a heavily doped segment for electrical contact and a lightly doped segment for passivation. This segmentation allows the system to achieve both low contact resistance and low carrier recombination simultaneously.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If the electrode structure is simplified to reduce manufacturing complexity, then the manufacturing process becomes easier, but the ability to maintain effective passivation while ensuring good contact deteriorates

Engineering Contradiction:

Improveelectrode structure fabricationVSAvoidpassivation effectiveness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The electrode structure is segmented into multiple components (electrode body, connecting electrodes, edge electrodes) that correspond to different functional regions of the doped layer. This segmentation allows each electrode component to be positioned and formed with appropriate complexity only where needed, balancing manufacturing ease with performance requirements.

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

This design enhances the open-circuit voltage, fill factor, and conversion efficiency of the solar cell by improving the ohmic contact and reducing carrier recombination while maintaining effective passivation.

Implementation Method 1

the first electrode forming an ohmic contact with the heavily doped region

Methodology Applied

Scientific EffectOhmic contact: Conduction (electrical)

Implementation Method 2

The selective emitter (SE) laser doping technology is a technology that performs diffusion in a contact region on a surface of a substrate to form a heavily doped region

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 3

carrier recombination in the lightly doped region can be effectively reduced

Methodology Applied

Scientific EffectCarrier recombination:

Data Source

PatentUS12568712B2Solar cell and manufacturing method thereof, photovoltaic module and photovoltaic system

Publication Date: 2026.03.03 TRINA SOLAR CO LTD

AI summary

A solar cell and a manufacturing method thereof, a photovoltaic module, and a photovoltaic system. A doped layer of the solar cell includes a lightly doped region and a heavily doped region, the heavily doped region includes a body region, connecting regions, and edge regions, and an electrode includes an electrode body, connecting electrodes and edge electrodes. The body region substantially corresponds to the electrode body, and the connecting regions and the edge regions can provide spaces exceeding the spaces corresponding to the connecting electrodes and the edge electrodes.