Transparent Metal Oxide Electrode UV Stability

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Solution Overview

Problem

Transparent metal oxide electrodes face challenges in maintaining high conductivity over time due to instability caused by exposure to oxygen, water vapor, and thermal loads, especially when subjected to UV radiation without proper protection.

Innovation Solution

Applying a substantially UV-transparent barrier layer on the transparent metal oxide before UV radiation exposure allows continuous UV treatment without coverage gaps, preventing degradation and maintaining high conductivity after irradiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If UV radiation is applied to transparent metal oxide to improve conductivity, then electrical conductivity is improved, but the metal oxide degrades when exposed to oxygen, water vapor, and thermal loads

Engineering Contradiction:
Improveelectrical conductivityVSAvoidenvironmental degradation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A barrier layer is introduced as an intermediary between the transparent metal oxide and the environment. This barrier layer protects the metal oxide from harmful environmental factors (oxygen, water vapor, thermal loads) while allowing UV radiation to pass through and maintain conductivity enhancement.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The barrier layer is applied before UV irradiation to prevent environmental degradation from occurring in the first place. By establishing protection in advance, the metal oxide maintains its enhanced conductivity without subsequent degradation from environmental exposure.

Inventive Principle:
Principle #10Preliminary action

2Object-affected harmful factors

If a barrier layer is applied after UV irradiation to protect the metal oxide, then environmental protection is provided, but conductivity is lost during the period before barrier application

Engineering Contradiction:
Improveenvironmental protectionVSAvoidconductivity stability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The barrier layer is applied in advance before UV irradiation and before environmental exposure occurs. This preliminary protection ensures that when UV irradiation enhances conductivity, the metal oxide is already protected from environmental factors that would otherwise cause degradation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The barrier layer serves as beforehand cushioning against environmental degradation. By being in place before UV irradiation and environmental exposure, it prevents the harmful effects from occurring during the critical period when conductivity enhancement is most vulnerable.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Object-affected harmful factors

If the barrier layer is not UV transparent, then environmental protection is improved, but UV radiation cannot reach the metal oxide to maintain conductivity

Engineering Contradiction:
Improveenvironmental protectionVSAvoidconductivity maintenance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The barrier layer is designed with specific local properties: it is substantially UV transparent to allow UV radiation to reach the metal oxide, while simultaneously providing protection against other environmental factors (oxygen, water vapor, thermal loads). This selective transparency creates different functional zones within the barrier layer.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The barrier layer is made from a composite material or specific material composition that combines UV transparency with environmental barrier properties. This allows the single layer to fulfill multiple functions: protecting against harmful factors while permitting UV radiation transmission.

Inventive Principle:
Principle #40Composite materials

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 method ensures stable high conductivity of the transparent conductive oxide layer, reducing square resistance to below 100 Ohm/square and maintaining it for an extended period without the need for vacuum conditions, with the barrier layer preventing environmental degradation.

Implementation Method 1

applying a substantially UV transparent barrier layer on the transparent metal oxide before UV radiation exposure allows continuous UV treatment without coverage gaps, preventing degradation and maintaining high conductivity after irradiation

Methodology Applied
Scientific EffectPhysical barrier protection:

Implementation Method 2

the conductivity of the zinc oxide can be improved by, for example, exposure to ultraviolet (UV) light. The conductivity of zinc oxide can be increased by exposure to light with an energy above the zinc oxide band gap (about 3.4 eV), i.e. UV radiation

Methodology Applied
Scientific EffectPhoto-induced defect formation: Photoconductivity

Implementation Method 3

applying a substantially UV transparent barrier layer on the transparent metal oxide before UV radiation exposure allows continuous UV treatment without coverage gaps

Methodology Applied
Scientific EffectSelective radiation transmission: Absorption (EM radiation)

Data Source

PatentEP2847769B1Method of making a transparent metal oxide electrode
Publication Date: 2018.07.04 NEDERLANDSE ORG VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK TNO
  • EP2847769B1 patent drawingFigure 1~1III
  • EP2847769B1 patent drawingFigure 2
  • EP2847769B1 patent drawingFigure 3

AI summary

The present invention relates to a method for enhancing the conductivity of an undoped transparent metal oxide to obtain a transparent conductive oxide (TCO) electrode. More in particular it relates to such a method comprising the steps of providing a transparent metal oxide (11), applying a UV transparent barrier layer (13) on the transparent metal oxide, and irradiating the transparent metal oxide with UV radiation (14) after applying the barrier layer.