Electrochromic Device with Oxide Semiconductor Metal Oxide Composite
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Solution Overview
Problem
Conventional electrochromic devices face challenges in reducing process temperature, achieving stable current characteristics, and improving driving and reliability, particularly in the application of electrochromic materials with specific energy bandgap ranges and conduction band energy level differences.
Innovation Solution
An electrochromic device is designed with a first and second electrode facing each other, an electrochromic layer comprising oxide semiconductor particles with metal oxide on their surfaces and an electrochromic material, where the energy bandgaps of the oxide semiconductor particles and metal oxide are within the range of 3 eV to 5 eV, and the conduction band energy level difference is 0.5 eV or less, along with a method of manufacturing that includes electrophoresis and heating to form the metal oxide at a temperature of 450°C or lower.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrochromic materials are used, then the device can achieve basic electrochromic function, but the process temperature remains high and reliability is insufficient
Solution Approach 1:
The patent changes the energy bandgap parameter of the semiconductor material to 3-5 eV and controls the conduction band energy level difference to 0.5 eV or less between semiconductor particles and metal oxide. This parameter optimization enables the formation of a continuous conduction band that facilitates low-temperature sintering (450°C or lower) while maintaining device reliability and electrochromic performance.
Solution Approach 2:
The patent creates a composite structure consisting of semiconductor particles with metal oxide on their surfaces. This composite material design allows the metal oxide to form a continuous conduction band network that enhances electrical conductivity and enables low-temperature processing, while the semiconductor particles provide the electrochromic active sites, achieving both reliability and low process temperature.
2Reliability
If the electrochromic layer uses simple material composition, then the manufacturing process is simpler, but current characteristics are unstable
Solution Approach 1:
The patent applies local quality by forming metal oxide specifically on the surfaces of semiconductor particles rather than using a uniform material composition throughout. This localized metal oxide coating creates continuous conduction bands at the particle interfaces, ensuring stable current characteristics, while the core semiconductor particles maintain their electrochromic functionality. The structure is complex only where needed for performance optimization.
3Illumination intensity
If high energy bandgap materials are used, then optical characteristics improve, but electrical conductivity decreases
Solution Approach 1:
The patent introduces metal oxide as an intermediary substance on the surfaces of high bandgap semiconductor particles. The metal oxide forms a continuous conduction band network that acts as a mediator, enabling efficient charge transport between the high bandgap semiconductor particles. This intermediary structure maintains the high optical characteristics of the semiconductor while providing the electrical conductivity needed for stable device operation.
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 solution enables lower process temperatures, improved electrical and chromatic characteristics, and enhanced reliability, allowing for flexible and cost-effective production of electrochromic devices with stable current characteristics and wide color gamut.
Implementation Method 1
dipping the first electrode and a reference electrode into the electrophoresis solution and applying a voltage to provide oxide semiconductor particles of which the metal ions are bonded to one surface of the first electrode
Implementation Method 2
heating the oxide semiconductor particles to form a metal oxide from the metal ions
Implementation Method 3
Electrochromism refers to a phenomenon in which a color reversibly changes by the direction of an electric field when a voltage is applied. A material having such property, that is, a material whose optical characteristic may reversibly change through an electrochemical redox reaction
Data Source
AI summary
Disclosed is an electrochromic device that includes a first electrode and a second electrode facing each other, an electrochromic layer between the first electrode and the second electrode, and an electrolyte between the first electrode and the second electrode and being in contact with the electrochromic layer. The electrochromic layer may include a plurality of oxide semiconductor particles, a metal oxide on the surface of the oxide semiconductor particles, and an electrochromic material. An energy bandgap of the oxide semiconductor particles is in a range of about 3 eV to about 5 eV and an energy bandgap of the metal oxide is in a range of about 3 eV to about 5 eV, and a difference of conduction band energy levels of the oxide semiconductor particles and the metal oxide is about 0.5 eV or less. A method of manufacturing the electrochromic device may also be provided.