Printable Hybrid Sol Gel for Local Boron Doping in Solar Cells

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Solution Overview

Problem

Current solar cell production methods require complex and costly processes for creating locally differentiated doping areas on silicon substrates, involving multiple masking steps and structuring processes, which are inefficient and difficult to scale for industrial mass production.

Innovation Solution

The use of printable hybrid sols and gels based on silicon dioxide, aluminum oxide, and boron oxide precursors, applied via printing technologies, which act as both doping media and diffusion barriers, allowing for simultaneous boron doping and inhibition of phosphorus diffusion, thereby simplifying the process and reducing the number of necessary steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional gas phase diffusion with phosphoryl chloride is used for phosphorus doping, then uniform doping can be achieved, but it is difficult to create locally differentiated doping areas without complex masking steps

Engineering Contradiction:
Improvelocal doping precisionVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by using printable doping media that can be selectively applied to specific areas of the silicon substrate. The printing process allows different doping compositions to be deposited in different locations, enabling local differentiation of doping areas without requiring masking steps. This directly addresses the contradiction by achieving precise local doping control while maintaining process simplicity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent replaces the mechanical masking system with a printing-based delivery system. Instead of using physical masks to define doping areas, the invention uses printable media that can be selectively deposited using printing technologies. This substitution eliminates the complexity of masking steps while maintaining the ability to create locally differentiated doping areas.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If multiple masking and structuring steps are used to create locally differentiated doping areas, then precise doping patterns can be achieved, but the production process becomes inefficient and difficult to scale

Engineering Contradiction:
Improvedoping pattern precisionVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent merges the doping delivery function and the patterning function into a single printing step. The printable doping media combines the dopant material with delivery mechanisms that enable selective deposition, allowing both precise pattern formation and doping to occur simultaneously. This merging eliminates the need for separate masking and structuring steps, thereby maintaining precision while improving productivity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The printable doping media serves multiple functions: it acts as the dopant source, the delivery vehicle, and the patterning tool all in one. This multi-functionality allows the single printing step to achieve what previously required multiple separate steps (masking, doping, mask removal), thereby maintaining doping pattern precision while significantly improving production efficiency and scalability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of manufacture

If printable doping media are used to simplify the doping process, then the number of process steps is reduced, but control over diffusion barriers may be compromised

Engineering Contradiction:
Improveprocess simplicityVSAvoiddiffusion control
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent employs composite materials in the form of printable doping media that integrate the dopant source with diffusion barrier properties. The media is formulated to provide both doping functionality and controlled diffusion characteristics, allowing the simplified printing process to maintain reliable control over dopant diffusion. This composite approach ensures that process simplicity does not compromise diffusion control.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent utilizes parameter changes in the printable media formulation to control diffusion behavior. By adjusting the composition, thickness, and thermal properties of the printable media, the diffusion characteristics can be precisely controlled. This allows the simplified printing process to maintain reliable diffusion control through material parameter optimization rather than complex process steps.

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 approach significantly reduces the number of process steps required for producing solar cells with structured dopings, such as IBC cells, by enabling simultaneous boron doping and preventing phosphorus diffusion, leading to cost-effective and efficient manufacturing of bifacial and high-efficiency solar cells.

Implementation Method 1

The printable hybrid sol and/or gel according to the invention can be used as a diffusion barrier or diffusion-inhibiting layer during the doping of silicon substrates with phosphorus

Methodology Applied
Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

which are brought to partial or complete intra- and/or interspecies condensation under water-containing or anhydrous conditions using the sol-gel technique... the degree of gelation of the resulting hybrid sols and gels is controlled in a targeted manner

Methodology Applied
Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 3

which are brought to partial or complete intra- and/or interspecies condensation under water-containing or anhydrous conditions using the sol-gel technique

Methodology Applied
Scientific EffectHydrolysis: Hydrolysis

Implementation Method 4

which are brought to partial or complete intra- and/or interspecies condensation under water-containing or anhydrous conditions using the sol-gel technique

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3284109B1Method for producing solar cells using phosphorus diffusion-inhibiting, printable doping media
Publication Date: 2019.06.19 MERCK PATENT GMBH
  • EP3284109B1 patent drawingFigure 3
  • EP3284109B1 patent drawingFigure 4~5
  • EP3284109B1 patent drawingFigure 6

AI summary

The present invention relates to a novel printable medium in the form of a hybrid sol and/or hybrid gel on the basis of inorganic oxide precursors which can be used in a simplified process for the production of solar cells, the medium according to the invention functioning as a doping medium as well as a diffusion barrier.