Oxidic Passivation Layer for Alkali-Doped Thin-Film Solar Cells

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional thin-film solar cells with alkali metal-doped photovoltaic absorber layers face efficiency reduction due to corrosion and recombination of light-induced charge carriers, leading to decreased performance and reproducibility.

Innovation Solution

An oxidic passivation layer, comprising materials like (In,Ga)2O3 and Mx(In,Ga)yOz, is applied to the front contact surface of the photovoltaic absorber layer to protect against corrosion and enhance p-n inversion, using alkali metals like Rb and Cs for improved efficiency and reproducibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If alkali metal doping is applied to the photovoltaic absorber layer, then the photoelectric activity and efficiency are improved, but the fill factor and efficiency are noticeably reduced due to corrosion and recombination

Engineering Contradiction:

ImproveefficiencyVSAvoidfill factor

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

An oxidic passivation layer is introduced as an intermediary between the alkali metal-doped photovoltaic absorber layer and the environment. This passivation layer mediates the interaction by preventing direct contact between corrosive atmospheric elements (oxygen, moisture) and the absorber layer surface, thereby eliminating the harmful corrosion effects while preserving the beneficial photoelectric enhancement from alkali metal doping.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful effect of alkali metal doping (which causes surface corrosion and charge carrier recombination) into a beneficial outcome by applying a thin oxidic passivation layer. This layer transforms the corrosive surface into a protected interface that actually enhances performance by preventing degradation pathways while maintaining the doping benefits.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If the photovoltaic absorber layer is exposed to atmospheric oxygen and moisture, then charge carrier recombination increases due to corrosion, but the layer structure becomes more complex with additional protective layers

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidlayer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A thin oxidic passivation layer is applied to the surface of the photovoltaic absorber layer to provide corrosion protection. This thin film approach protects against atmospheric oxygen and moisture without adding significant structural complexity, maintaining device simplicity while achieving reliable corrosion resistance.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If a transparent barrier layer is applied to protect against moisture and oxygen degradation, then corrosion resistance is improved, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvemoisture resistanceVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the chemical composition and properties of the absorber layer surface by introducing an oxidic passivation layer. This parameter change transforms the surface chemistry to be inherently more resistant to moisture and oxygen degradation, achieving improved reliability while the integration into existing manufacturing processes maintains ease of manufacture.

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

The oxidic passivation layer effectively delays corrosion, reduces charge carrier recombination, and maintains high efficiency throughout the solar cell's service life, while allowing for reduced buffer layer thickness and improved diffusion barrier properties.

Implementation Method 1

an oxidic passivation layer on a surface of a photovoltaic absorber layer which is built into the photovoltaic absorber layer and which is designed for this purpose to protect the photovoltaic absorber layer from corrosion

Methodology Applied

Scientific EffectPassivation:

Implementation Method 2

a photovoltaic absorber layer which is doped with at least one alkali metal

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Implementation Method 3

alkali metal doping can have a favorable effect on the properties of the absorber layer, which are relevant for the photoelectric activity

Methodology Applied

Scientific EffectDoping: Dopants

Data Source

PatentEP3221899B1Layer structure for a thin-film solar cell and production method

Publication Date: 2023.07.12 ZENT FUR SONNENENERGIE & WASSERSTOFF FORSCHUNG BADEN WURTTEMBERG GEMEINNUTZIGE STIFTUNG

Figure 1
Figure 2

AI summary

The invention relates to a layer structure for a thin-film solar cell (1), said structure comprising a photovoltaic absorber layer (5) doped, at least in a region bordering a surface (6) of the photovoltaic absorber layer, with at least one alkali metal. The invention also relates to a method for producing a layer structure of this type. According to the invention, the layer structure has an oxidic passivation layer (8) on the surface (6) of the photovoltaic absorber layer (5), said passivation layer being designed to protect the photovoltaic absorber layer against corrosion.