Potassium Tungsten Oxide Electrochromic Layer for Fast Switching

Solution Overview

Problem

Existing electrochromic devices face challenges in achieving rapid color switching and long-term performance due to limitations in the reversible reaction rate and degradation of initial characteristics, particularly when using tungsten oxide materials without optimized potassium distribution and crystal periodicity.

Innovation Solution

Incorporating potassium-containing tungsten oxide particles with an average size of 100 nm or less, where potassium content ranges from 1 mol % to 50 mol %, and featuring a central section and peripheral section with varying crystal periodicity, enhancing electron transfer rates and stability within the electrochromic layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional tungsten oxide materials are used without optimized potassium distribution, then manufacturing is simpler, but the response time for color switching is slower and initial performance is reduced

Engineering Contradiction:

Improveresponse time for color switchingVSAvoidcomplexity of potassium distribution structure

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating distinct regions within the tungsten oxide layer: a first region with higher potassium concentration near the electrolyte interface and a second region with lower potassium concentration deeper in the layer. This spatial variation in potassium distribution optimizes both ion insertion/extraction kinetics at the interface and structural stability in the bulk, thereby improving color switching response time without requiring uniform complex doping throughout the entire material.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by pre-distributing potassium ions in specific concentration gradients during the formation of the tungsten oxide layer, before the device operates. This pre-arranged potassium distribution prepares the material with optimal hopping conduction pathways and crystal structure stability in advance, enabling faster initial response and maintaining performance during repeated cycling without requiring real-time adjustment.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If conventional tungsten oxide materials are used without crystal periodicity optimization, then manufacturing is easier, but the rate of reversible reaction and long-term stability are reduced

Engineering Contradiction:

Improvelong-term stability and reversible reaction rateVSAvoidprecision of crystal periodicity control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating distinct regions within the tungsten oxide layer: a first region with higher potassium concentration near the electrolyte interface and a second region with lower potassium concentration deeper in the layer. This spatial variation in potassium distribution optimizes both ion insertion/extraction kinetics at the interface and structural stability in the bulk, thereby improving color switching response time without requiring uniform complex doping throughout the entire material.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by systematically varying the potassium concentration as a gradient parameter through the tungsten oxide layer thickness. By controlling the concentration parameter of potassium from 1-30 at% in the first region to 0.1-10 at% in the second region, the patent optimizes the balance between hopping conduction efficiency (requiring higher potassium) and crystal structure stability (maintained with lower potassium), achieving both fast reversible reaction rates and long-term reliability.

Inventive Principle:

Principle #35Parameter changes

3Speed

If potassium content is increased to improve electron transfer, then color switching speed improves, but degradation of initial characteristics occurs faster

Engineering Contradiction:

Improveelectron transfer rateVSAvoidduration of initial performance

Core Design Contradiction:

SpeedVSDuration of action of stationary object

Solution Approach 1:

The patent applies local quality by creating distinct regions within the tungsten oxide layer: a first region with higher potassium concentration near the electrolyte interface and a second region with lower potassium concentration deeper in the layer. This spatial variation in potassium distribution optimizes both ion insertion/extraction kinetics at the interface and structural stability in the bulk, thereby improving color switching response time without requiring uniform complex doping throughout the entire material.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by systematically varying the potassium concentration as a gradient parameter through the tungsten oxide layer thickness. By controlling the concentration parameter of potassium from 1-30 at% in the first region to 0.1-10 at% in the second region, the patent optimizes the balance between hopping conduction efficiency (requiring higher potassium) and crystal structure stability (maintained with lower potassium), achieving both fast reversible reaction rates and long-term reliability.

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 configuration significantly improves the response time for color switching and maintains the electrochromic device's performance over time by facilitating faster and more efficient electron transfer, thereby extending the device's lifespan.

Implementation Method 1

an attempt has been made to provide a hopping conduction characteristic to a material for the electrochromic devices

Methodology Applied

Scientific EffectHopping conduction:

Implementation Method 2

A reversible reaction occurring when an electric charge is applied to a material that exhibits electrochromism is an oxidation-reduction reaction that involves a transfer of electrons

Methodology Applied

Scientific EffectOxidation-reduction reaction: Redox Reactions

Implementation Method 3

Electrochromic devices are devices which utilize a reversible change in photophysical properties upon applying electric charge to a substance

Methodology Applied

Scientific EffectElectrochromism: Electrochromism

Data Source

PatentUS11884882B2Electrochromic device

Publication Date: 2024.01.30 TOSHIBA MATERIALS CO LTD

AI summary

According to one embodiment, provided is an electrochromic device including an electrochromic layer, which contains a tungsten oxide material. The tungsten oxide material includes potassium-containing tungsten oxide particles having an average particle size of 100 nm or less. The potassium-containing tungsten oxide particles contain potassium within a range of 1 mol % to 50 mol %, and include a central section and a peripheral section adjacent to the central section. A periodicity of a crystal varies between the central section and the peripheral section.