Heterojunction Solar Cell Annealing With Hydrogen Passivation

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Solution Overview

Problem

Existing methods for producing heterosolar cells face limitations in achieving high open-circuit voltage and require narrow process windows for temperature and material parameters, which restricts the flexibility and efficiency of the solar cell production process.

Innovation Solution

A method involving the formation of a heterojunction with a doped SiC layer, where the heterojunction layer is heated to at least 600 °C and hydrogen is diffused into the layer or interface, allowing for a broader temperature range and improved electrical quality, and the use of undoped regions between p- and n-doped regions in the heterojunction layer to prevent recombination losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing methods are used to produce heterosolar cells, then the production process can be completed, but the open-circuit voltage is limited and process windows are narrow

Engineering Contradiction:

Improveopen-circuit voltageVSAvoidprocess window flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by heating the heterojunction layer to at least 600°C, which fundamentally alters the electrical properties of the layer. This temperature parameter change enables the achievement of high open-circuit voltages while simultaneously widening the acceptable process window for temperature and material parameters, resolving the contradiction between reliability and adaptability

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the heterojunction layer is heated to high temperature, then electrical quality improves, but recombination losses may occur without proper hydrogen diffusion

Engineering Contradiction:

Improveelectrical qualityVSAvoidrecombination losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by performing hydrogen diffusion into the heterojunction layer before or during the high-temperature heating process. This preliminary hydrogenation prevents recombination losses that would otherwise occur during heating, while still allowing the electrical quality to improve through the temperature treatment. The hydrogen is pre-introduced to protect against energy losses

Inventive Principle:

Principle #10Preliminary action

3Reliability

If doped regions are used throughout the heterojunction layer, then electrical conductivity is maintained, but recombination losses increase at interfaces

Engineering Contradiction:

Improveelectrical conductivityVSAvoidrecombination losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating undoped regions between p-doped and n-doped regions within the heterojunction layer. These undoped zones serve as recombination-free interfaces, while the doped regions maintain electrical conductivity. This spatial differentiation of doping quality resolves the contradiction by allowing conductivity where needed while preventing recombination losses at interfaces

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 method enhances the open-circuit voltage and widens the process windows for temperature, temperature stability, and material quality, enabling more flexible and efficient solar cell production while maintaining high electrical quality and avoiding recombination losses.

Implementation Method 1

a dielectric tunnel layer which is arranged directly between the heterojunction layer and the semiconductor substrate

Methodology Applied

Scientific EffectQuantum tunneling:

Implementation Method 2

the heterojunction layer is heated to at least 600 °C

Methodology Applied

Scientific EffectThermal annealing: Annealing

Implementation Method 3

heated to at least 600 °C to improve the electrical quality of the heterojunction

Methodology Applied

Scientific EffectThermal activation:

Implementation Method 4

hydrogen is diffused into the heterojunction layer and/or at the interface between the tunnel layer and the semiconductor substrate

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentEP3930013B1Method for producing a photovoltaic solar cell with at least one heterojunction

Publication Date: 2024.01.31 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

Figure 1~2
Figure 3~4
Figure 5a~5b

AI summary

The invention relates to a method for manufacturing a photovoltaic solar cell with at least one heterojunction, comprising the following process steps: A. Providing a semiconductor substrate with a base doping; B. Creating a heterojunction on at least one side of the semiconductor substrate, which heterojunction has a doped heterojunction layer and a dielectric tunnel layer arranged directly or indirectly between the heterojunction layer and the semiconductor substrate; C. Heating at least the heterojunction layer to improve the electrical quality of the heterojunction; The invention is characterized in that, in a process step D following process step C, hydrogen is diffused into the heterojunction layer and/or to the interface between the tunnel layer and the semiconductor substrate.